// Copyright (c) 2014-2020, The Monero Project
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// Parts of this file are originally copyright (c) 2012-2013 The Cryptonote developers
# include <unordered_set>
# include <random>
# include "include_base_utils.h"
# include "string_tools.h"
using namespace epee ;
# include "common/apply_permutation.h"
# include "cryptonote_tx_utils.h"
# include "cryptonote_config.h"
# include "blockchain.h"
# include "cryptonote_basic/miner.h"
# include "cryptonote_basic/tx_extra.h"
# include "crypto/crypto.h"
# include "crypto/hash.h"
# include "ringct/rctSigs.h"
# include "multisig/multisig.h"
using namespace crypto ;
namespace cryptonote
{
Add N/N multisig tx generation and signing
Scheme by luigi1111:
Multisig for RingCT on Monero
2 of 2
User A (coordinator):
Spendkey b,B
Viewkey a,A (shared)
User B:
Spendkey c,C
Viewkey a,A (shared)
Public Address: C+B, A
Both have their own watch only wallet via C+B, a
A will coordinate spending process (though B could easily as well, coordinator is more needed for more participants)
A and B watch for incoming outputs
B creates "half" key images for discovered output D:
I2_D = (Hs(aR)+c) * Hp(D)
B also creates 1.5 random keypairs (one scalar and 2 pubkeys; one on base G and one on base Hp(D)) for each output, storing the scalar(k) (linked to D),
and sending the pubkeys with I2_D.
A also creates "half" key images:
I1_D = (Hs(aR)+b) * Hp(D)
Then I_D = I1_D + I2_D
Having I_D allows A to check spent status of course, but more importantly allows A to actually build a transaction prefix (and thus transaction).
A builds the transaction until most of the way through MLSAG_Gen, adding the 2 pubkeys (per input) provided with I2_D
to his own generated ones where they are needed (secret row L, R).
At this point, A has a mostly completed transaction (but with an invalid/incomplete signature). A sends over the tx and includes r,
which allows B (with the recipient's address) to verify the destination and amount (by reconstructing the stealth address and decoding ecdhInfo).
B then finishes the signature by computing ss[secret_index][0] = ss[secret_index][0] + k - cc[secret_index]*c (secret indices need to be passed as well).
B can then broadcast the tx, or send it back to A for broadcasting. Once B has completed the signing (and verified the tx to be valid), he can add the full I_D
to his cache, allowing him to verify spent status as well.
NOTE:
A and B *must* present key A and B to each other with a valid signature proving they know a and b respectively.
Otherwise, trickery like the following becomes possible:
A creates viewkey a,A, spendkey b,B, and sends a,A,B to B.
B creates a fake key C = zG - B. B sends C back to A.
The combined spendkey C+B then equals zG, allowing B to spend funds at any time!
The signature fixes this, because B does not know a c corresponding to C (and thus can't produce a signature).
2 of 3
User A (coordinator)
Shared viewkey a,A
"spendkey" j,J
User B
"spendkey" k,K
User C
"spendkey" m,M
A collects K and M from B and C
B collects J and M from A and C
C collects J and K from A and B
A computes N = nG, n = Hs(jK)
A computes O = oG, o = Hs(jM)
B anc C compute P = pG, p = Hs(kM) || Hs(mK)
B and C can also compute N and O respectively if they wish to be able to coordinate
Address: N+O+P, A
The rest follows as above. The coordinator possesses 2 of 3 needed keys; he can get the other
needed part of the signature/key images from either of the other two.
Alternatively, if secure communication exists between parties:
A gives j to B
B gives k to C
C gives m to A
Address: J+K+M, A
3 of 3
Identical to 2 of 2, except the coordinator must collect the key images from both of the others.
The transaction must also be passed an additional hop: A -> B -> C (or A -> C -> B), who can then broadcast it
or send it back to A.
N-1 of N
Generally the same as 2 of 3, except participants need to be arranged in a ring to pass their keys around
(using either the secure or insecure method).
For example (ignoring viewkey so letters line up):
[4 of 5]
User: spendkey
A: a
B: b
C: c
D: d
E: e
a -> B, b -> C, c -> D, d -> E, e -> A
Order of signing does not matter, it just must reach n-1 users. A "remaining keys" list must be passed around with
the transaction so the signers know if they should use 1 or both keys.
Collecting key image parts becomes a little messy, but basically every wallet sends over both of their parts with a tag for each.
Thia way the coordinating wallet can keep track of which images have been added and which wallet they come from. Reasoning:
1. The key images must be added only once (coordinator will get key images for key a from both A and B, he must add only one to get the proper key actual key image)
2. The coordinator must keep track of which helper pubkeys came from which wallet (discussed in 2 of 2 section). The coordinator
must choose only one set to use, then include his choice in the "remaining keys" list so the other wallets know which of their keys to use.
You can generalize it further to N-2 of N or even M of N, but I'm not sure there's legitimate demand to justify the complexity. It might
also be straightforward enough to support with minimal changes from N-1 format.
You basically just give each user additional keys for each additional "-1" you desire. N-2 would be 3 keys per user, N-3 4 keys, etc.
The process is somewhat cumbersome:
To create a N/N multisig wallet:
- each participant creates a normal wallet
- each participant runs "prepare_multisig", and sends the resulting string to every other participant
- each participant runs "make_multisig N A B C D...", with N being the threshold and A B C D... being the strings received from other participants (the threshold must currently equal N)
As txes are received, participants' wallets will need to synchronize so that those new outputs may be spent:
- each participant runs "export_multisig FILENAME", and sends the FILENAME file to every other participant
- each participant runs "import_multisig A B C D...", with A B C D... being the filenames received from other participants
Then, a transaction may be initiated:
- one of the participants runs "transfer ADDRESS AMOUNT"
- this partly signed transaction will be written to the "multisig_monero_tx" file
- the initiator sends this file to another participant
- that other participant runs "sign_multisig multisig_monero_tx"
- the resulting transaction is written to the "multisig_monero_tx" file again
- if the threshold was not reached, the file must be sent to another participant, until enough have signed
- the last participant to sign runs "submit_multisig multisig_monero_tx" to relay the transaction to the Monero network
7 years ago
//---------------------------------------------------------------
void classify_addresses ( const std : : vector < tx_destination_entry > & destinations , const boost : : optional < cryptonote : : account_public_address > & change_addr , size_t & num_stdaddresses , size_t & num_subaddresses , account_public_address & single_dest_subaddress )
{
num_stdaddresses = 0 ;
num_subaddresses = 0 ;
std : : unordered_set < cryptonote : : account_public_address > unique_dst_addresses ;
for ( const tx_destination_entry & dst_entr : destinations )
{
if ( change_addr & & dst_entr . addr = = change_addr )
continue ;
if ( unique_dst_addresses . count ( dst_entr . addr ) = = 0 )
{
unique_dst_addresses . insert ( dst_entr . addr ) ;
if ( dst_entr . is_subaddress )
{
+ + num_subaddresses ;
single_dest_subaddress = dst_entr . addr ;
}
else
{
+ + num_stdaddresses ;
}
}
}
LOG_PRINT_L2 ( " destinations include " < < num_stdaddresses < < " standard addresses and " < < num_subaddresses < < " subaddresses " ) ;
}
//---------------------------------------------------------------
bool construct_miner_tx ( size_t height , size_t median_weight , uint64_t already_generated_coins , size_t current_block_weight , uint64_t fee , const account_public_address & miner_address , transaction & tx , const blobdata & extra_nonce , size_t max_outs , uint8_t hard_fork_version ) {
tx . vin . clear ( ) ;
tx . vout . clear ( ) ;
tx . extra . clear ( ) ;
keypair txkey = keypair : : generate ( hw : : get_device ( " default " ) ) ;
add_tx_pub_key_to_extra ( tx , txkey . pub ) ;
if ( ! extra_nonce . empty ( ) )
if ( ! add_extra_nonce_to_tx_extra ( tx . extra , extra_nonce ) )
return false ;
if ( ! sort_tx_extra ( tx . extra , tx . extra ) )
return false ;
txin_gen in ;
in . height = height ;
uint64_t block_reward ;
if ( ! get_block_reward ( median_weight , current_block_weight , already_generated_coins , block_reward , hard_fork_version ) )
{
LOG_PRINT_L0 ( " Block is too big " ) ;
return false ;
}
# if defined(DEBUG_CREATE_BLOCK_TEMPLATE)
LOG_PRINT_L1 ( " Creating block template: reward " < < block_reward < <
" , fee " < < fee ) ;
# endif
block_reward + = fee ;
// from hard fork 2, we cut out the low significant digits. This makes the tx smaller, and
// keeps the paid amount almost the same. The unpaid remainder gets pushed back to the
// emission schedule
// from hard fork 4, we use a single "dusty" output. This makes the tx even smaller,
// and avoids the quantization. These outputs will be added as rct outputs with identity
// masks, to they can be used as rct inputs.
if ( hard_fork_version > = 2 & & hard_fork_version < 4 ) {
block_reward = block_reward - block_reward % : : config : : BASE_REWARD_CLAMP_THRESHOLD ;
}
std : : vector < uint64_t > out_amounts ;
decompose_amount_into_digits ( block_reward , hard_fork_version > = 2 ? 0 : : : config : : DEFAULT_DUST_THRESHOLD ,
[ & out_amounts ] ( uint64_t a_chunk ) { out_amounts . push_back ( a_chunk ) ; } ,
[ & out_amounts ] ( uint64_t a_dust ) { out_amounts . push_back ( a_dust ) ; } ) ;
CHECK_AND_ASSERT_MES ( 1 < = max_outs , false , " max_out must be non-zero " ) ;
if ( height = = 0 | | hard_fork_version > = 4 )
{
// the genesis block was not decomposed, for unknown reasons
while ( max_outs < out_amounts . size ( ) )
{
//out_amounts[out_amounts.size() - 2] += out_amounts.back();
//out_amounts.resize(out_amounts.size() - 1);
out_amounts [ 1 ] + = out_amounts [ 0 ] ;
for ( size_t n = 1 ; n < out_amounts . size ( ) ; + + n )
out_amounts [ n - 1 ] = out_amounts [ n ] ;
out_amounts . pop_back ( ) ;
}
}
else
{
CHECK_AND_ASSERT_MES ( max_outs > = out_amounts . size ( ) , false , " max_out exceeded " ) ;
}
uint64_t summary_amounts = 0 ;
for ( size_t no = 0 ; no < out_amounts . size ( ) ; no + + )
{
crypto : : key_derivation derivation = AUTO_VAL_INIT ( derivation ) ;
crypto : : public_key out_eph_public_key = AUTO_VAL_INIT ( out_eph_public_key ) ;
bool r = crypto : : generate_key_derivation ( miner_address . m_view_public_key , txkey . sec , derivation ) ;
CHECK_AND_ASSERT_MES ( r , false , " while creating outs: failed to generate_key_derivation( " < < miner_address . m_view_public_key < < " , " < < txkey . sec < < " ) " ) ;
r = crypto : : derive_public_key ( derivation , no , miner_address . m_spend_public_key , out_eph_public_key ) ;
CHECK_AND_ASSERT_MES ( r , false , " while creating outs: failed to derive_public_key( " < < derivation < < " , " < < no < < " , " < < miner_address . m_spend_public_key < < " ) " ) ;
txout_to_key tk ;
tk . key = out_eph_public_key ;
tx_out out ;
summary_amounts + = out . amount = out_amounts [ no ] ;
out . target = tk ;
tx . vout . push_back ( out ) ;
}
CHECK_AND_ASSERT_MES ( summary_amounts = = block_reward , false , " Failed to construct miner tx, summary_amounts = " < < summary_amounts < < " not equal block_reward = " < < block_reward ) ;
if ( hard_fork_version > = 4 )
tx . version = 2 ;
else
tx . version = 1 ;
//lock
tx . unlock_time = height + CRYPTONOTE_MINED_MONEY_UNLOCK_WINDOW ;
tx . vin . push_back ( in ) ;
tx . invalidate_hashes ( ) ;
//LOG_PRINT("MINER_TX generated ok, block_reward=" << print_money(block_reward) << "(" << print_money(block_reward - fee) << "+" << print_money(fee)
// << "), current_block_size=" << current_block_size << ", already_generated_coins=" << already_generated_coins << ", tx_id=" << get_transaction_hash(tx), LOG_LEVEL_2);
return true ;
}
//---------------------------------------------------------------
crypto : : public_key get_destination_view_key_pub ( const std : : vector < tx_destination_entry > & destinations , const boost : : optional < cryptonote : : account_public_address > & change_addr )
{
account_public_address addr = { null_pkey , null_pkey } ;
size_t count = 0 ;
for ( const auto & i : destinations )
{
if ( i . amount = = 0 )
continue ;
if ( change_addr & & i . addr = = * change_addr )
continue ;
if ( i . addr = = addr )
continue ;
if ( count > 0 )
return null_pkey ;
addr = i . addr ;
+ + count ;
}
if ( count = = 0 & & change_addr )
return change_addr - > m_view_public_key ;
return addr . m_view_public_key ;
}
//---------------------------------------------------------------
bool construct_tx_with_tx_key ( const account_keys & sender_account_keys , const std : : unordered_map < crypto : : public_key , subaddress_index > & subaddresses , std : : vector < tx_source_entry > & sources , std : : vector < tx_destination_entry > & destinations , const boost : : optional < cryptonote : : account_public_address > & change_addr , const std : : vector < uint8_t > & extra , transaction & tx , uint64_t unlock_time , const crypto : : secret_key & tx_key , const std : : vector < crypto : : secret_key > & additional_tx_keys , bool rct , const rct : : RCTConfig & rct_config , rct : : multisig_out * msout , bool shuffle_outs )
{
hw : : device & hwdev = sender_account_keys . get_device ( ) ;
if ( sources . empty ( ) )
{
LOG_ERROR ( " Empty sources " ) ;
return false ;
}
std : : vector < rct : : key > amount_keys ;
tx . set_null ( ) ;
amount_keys . clear ( ) ;
Add N/N multisig tx generation and signing
Scheme by luigi1111:
Multisig for RingCT on Monero
2 of 2
User A (coordinator):
Spendkey b,B
Viewkey a,A (shared)
User B:
Spendkey c,C
Viewkey a,A (shared)
Public Address: C+B, A
Both have their own watch only wallet via C+B, a
A will coordinate spending process (though B could easily as well, coordinator is more needed for more participants)
A and B watch for incoming outputs
B creates "half" key images for discovered output D:
I2_D = (Hs(aR)+c) * Hp(D)
B also creates 1.5 random keypairs (one scalar and 2 pubkeys; one on base G and one on base Hp(D)) for each output, storing the scalar(k) (linked to D),
and sending the pubkeys with I2_D.
A also creates "half" key images:
I1_D = (Hs(aR)+b) * Hp(D)
Then I_D = I1_D + I2_D
Having I_D allows A to check spent status of course, but more importantly allows A to actually build a transaction prefix (and thus transaction).
A builds the transaction until most of the way through MLSAG_Gen, adding the 2 pubkeys (per input) provided with I2_D
to his own generated ones where they are needed (secret row L, R).
At this point, A has a mostly completed transaction (but with an invalid/incomplete signature). A sends over the tx and includes r,
which allows B (with the recipient's address) to verify the destination and amount (by reconstructing the stealth address and decoding ecdhInfo).
B then finishes the signature by computing ss[secret_index][0] = ss[secret_index][0] + k - cc[secret_index]*c (secret indices need to be passed as well).
B can then broadcast the tx, or send it back to A for broadcasting. Once B has completed the signing (and verified the tx to be valid), he can add the full I_D
to his cache, allowing him to verify spent status as well.
NOTE:
A and B *must* present key A and B to each other with a valid signature proving they know a and b respectively.
Otherwise, trickery like the following becomes possible:
A creates viewkey a,A, spendkey b,B, and sends a,A,B to B.
B creates a fake key C = zG - B. B sends C back to A.
The combined spendkey C+B then equals zG, allowing B to spend funds at any time!
The signature fixes this, because B does not know a c corresponding to C (and thus can't produce a signature).
2 of 3
User A (coordinator)
Shared viewkey a,A
"spendkey" j,J
User B
"spendkey" k,K
User C
"spendkey" m,M
A collects K and M from B and C
B collects J and M from A and C
C collects J and K from A and B
A computes N = nG, n = Hs(jK)
A computes O = oG, o = Hs(jM)
B anc C compute P = pG, p = Hs(kM) || Hs(mK)
B and C can also compute N and O respectively if they wish to be able to coordinate
Address: N+O+P, A
The rest follows as above. The coordinator possesses 2 of 3 needed keys; he can get the other
needed part of the signature/key images from either of the other two.
Alternatively, if secure communication exists between parties:
A gives j to B
B gives k to C
C gives m to A
Address: J+K+M, A
3 of 3
Identical to 2 of 2, except the coordinator must collect the key images from both of the others.
The transaction must also be passed an additional hop: A -> B -> C (or A -> C -> B), who can then broadcast it
or send it back to A.
N-1 of N
Generally the same as 2 of 3, except participants need to be arranged in a ring to pass their keys around
(using either the secure or insecure method).
For example (ignoring viewkey so letters line up):
[4 of 5]
User: spendkey
A: a
B: b
C: c
D: d
E: e
a -> B, b -> C, c -> D, d -> E, e -> A
Order of signing does not matter, it just must reach n-1 users. A "remaining keys" list must be passed around with
the transaction so the signers know if they should use 1 or both keys.
Collecting key image parts becomes a little messy, but basically every wallet sends over both of their parts with a tag for each.
Thia way the coordinating wallet can keep track of which images have been added and which wallet they come from. Reasoning:
1. The key images must be added only once (coordinator will get key images for key a from both A and B, he must add only one to get the proper key actual key image)
2. The coordinator must keep track of which helper pubkeys came from which wallet (discussed in 2 of 2 section). The coordinator
must choose only one set to use, then include his choice in the "remaining keys" list so the other wallets know which of their keys to use.
You can generalize it further to N-2 of N or even M of N, but I'm not sure there's legitimate demand to justify the complexity. It might
also be straightforward enough to support with minimal changes from N-1 format.
You basically just give each user additional keys for each additional "-1" you desire. N-2 would be 3 keys per user, N-3 4 keys, etc.
The process is somewhat cumbersome:
To create a N/N multisig wallet:
- each participant creates a normal wallet
- each participant runs "prepare_multisig", and sends the resulting string to every other participant
- each participant runs "make_multisig N A B C D...", with N being the threshold and A B C D... being the strings received from other participants (the threshold must currently equal N)
As txes are received, participants' wallets will need to synchronize so that those new outputs may be spent:
- each participant runs "export_multisig FILENAME", and sends the FILENAME file to every other participant
- each participant runs "import_multisig A B C D...", with A B C D... being the filenames received from other participants
Then, a transaction may be initiated:
- one of the participants runs "transfer ADDRESS AMOUNT"
- this partly signed transaction will be written to the "multisig_monero_tx" file
- the initiator sends this file to another participant
- that other participant runs "sign_multisig multisig_monero_tx"
- the resulting transaction is written to the "multisig_monero_tx" file again
- if the threshold was not reached, the file must be sent to another participant, until enough have signed
- the last participant to sign runs "submit_multisig multisig_monero_tx" to relay the transaction to the Monero network
7 years ago
if ( msout )
{
msout - > c . clear ( ) ;
}
tx . version = rct ? 2 : 1 ;
tx . unlock_time = unlock_time ;
tx . extra = extra ;
Add N/N multisig tx generation and signing
Scheme by luigi1111:
Multisig for RingCT on Monero
2 of 2
User A (coordinator):
Spendkey b,B
Viewkey a,A (shared)
User B:
Spendkey c,C
Viewkey a,A (shared)
Public Address: C+B, A
Both have their own watch only wallet via C+B, a
A will coordinate spending process (though B could easily as well, coordinator is more needed for more participants)
A and B watch for incoming outputs
B creates "half" key images for discovered output D:
I2_D = (Hs(aR)+c) * Hp(D)
B also creates 1.5 random keypairs (one scalar and 2 pubkeys; one on base G and one on base Hp(D)) for each output, storing the scalar(k) (linked to D),
and sending the pubkeys with I2_D.
A also creates "half" key images:
I1_D = (Hs(aR)+b) * Hp(D)
Then I_D = I1_D + I2_D
Having I_D allows A to check spent status of course, but more importantly allows A to actually build a transaction prefix (and thus transaction).
A builds the transaction until most of the way through MLSAG_Gen, adding the 2 pubkeys (per input) provided with I2_D
to his own generated ones where they are needed (secret row L, R).
At this point, A has a mostly completed transaction (but with an invalid/incomplete signature). A sends over the tx and includes r,
which allows B (with the recipient's address) to verify the destination and amount (by reconstructing the stealth address and decoding ecdhInfo).
B then finishes the signature by computing ss[secret_index][0] = ss[secret_index][0] + k - cc[secret_index]*c (secret indices need to be passed as well).
B can then broadcast the tx, or send it back to A for broadcasting. Once B has completed the signing (and verified the tx to be valid), he can add the full I_D
to his cache, allowing him to verify spent status as well.
NOTE:
A and B *must* present key A and B to each other with a valid signature proving they know a and b respectively.
Otherwise, trickery like the following becomes possible:
A creates viewkey a,A, spendkey b,B, and sends a,A,B to B.
B creates a fake key C = zG - B. B sends C back to A.
The combined spendkey C+B then equals zG, allowing B to spend funds at any time!
The signature fixes this, because B does not know a c corresponding to C (and thus can't produce a signature).
2 of 3
User A (coordinator)
Shared viewkey a,A
"spendkey" j,J
User B
"spendkey" k,K
User C
"spendkey" m,M
A collects K and M from B and C
B collects J and M from A and C
C collects J and K from A and B
A computes N = nG, n = Hs(jK)
A computes O = oG, o = Hs(jM)
B anc C compute P = pG, p = Hs(kM) || Hs(mK)
B and C can also compute N and O respectively if they wish to be able to coordinate
Address: N+O+P, A
The rest follows as above. The coordinator possesses 2 of 3 needed keys; he can get the other
needed part of the signature/key images from either of the other two.
Alternatively, if secure communication exists between parties:
A gives j to B
B gives k to C
C gives m to A
Address: J+K+M, A
3 of 3
Identical to 2 of 2, except the coordinator must collect the key images from both of the others.
The transaction must also be passed an additional hop: A -> B -> C (or A -> C -> B), who can then broadcast it
or send it back to A.
N-1 of N
Generally the same as 2 of 3, except participants need to be arranged in a ring to pass their keys around
(using either the secure or insecure method).
For example (ignoring viewkey so letters line up):
[4 of 5]
User: spendkey
A: a
B: b
C: c
D: d
E: e
a -> B, b -> C, c -> D, d -> E, e -> A
Order of signing does not matter, it just must reach n-1 users. A "remaining keys" list must be passed around with
the transaction so the signers know if they should use 1 or both keys.
Collecting key image parts becomes a little messy, but basically every wallet sends over both of their parts with a tag for each.
Thia way the coordinating wallet can keep track of which images have been added and which wallet they come from. Reasoning:
1. The key images must be added only once (coordinator will get key images for key a from both A and B, he must add only one to get the proper key actual key image)
2. The coordinator must keep track of which helper pubkeys came from which wallet (discussed in 2 of 2 section). The coordinator
must choose only one set to use, then include his choice in the "remaining keys" list so the other wallets know which of their keys to use.
You can generalize it further to N-2 of N or even M of N, but I'm not sure there's legitimate demand to justify the complexity. It might
also be straightforward enough to support with minimal changes from N-1 format.
You basically just give each user additional keys for each additional "-1" you desire. N-2 would be 3 keys per user, N-3 4 keys, etc.
The process is somewhat cumbersome:
To create a N/N multisig wallet:
- each participant creates a normal wallet
- each participant runs "prepare_multisig", and sends the resulting string to every other participant
- each participant runs "make_multisig N A B C D...", with N being the threshold and A B C D... being the strings received from other participants (the threshold must currently equal N)
As txes are received, participants' wallets will need to synchronize so that those new outputs may be spent:
- each participant runs "export_multisig FILENAME", and sends the FILENAME file to every other participant
- each participant runs "import_multisig A B C D...", with A B C D... being the filenames received from other participants
Then, a transaction may be initiated:
- one of the participants runs "transfer ADDRESS AMOUNT"
- this partly signed transaction will be written to the "multisig_monero_tx" file
- the initiator sends this file to another participant
- that other participant runs "sign_multisig multisig_monero_tx"
- the resulting transaction is written to the "multisig_monero_tx" file again
- if the threshold was not reached, the file must be sent to another participant, until enough have signed
- the last participant to sign runs "submit_multisig multisig_monero_tx" to relay the transaction to the Monero network
7 years ago
crypto : : public_key txkey_pub ;
// if we have a stealth payment id, find it and encrypt it with the tx key now
std : : vector < tx_extra_field > tx_extra_fields ;
if ( parse_tx_extra ( tx . extra , tx_extra_fields ) )
{
bool add_dummy_payment_id = true ;
tx_extra_nonce extra_nonce ;
if ( find_tx_extra_field_by_type ( tx_extra_fields , extra_nonce ) )
{
crypto : : hash payment_id = null_hash ;
crypto : : hash8 payment_id8 = null_hash8 ;
if ( get_encrypted_payment_id_from_tx_extra_nonce ( extra_nonce . nonce , payment_id8 ) )
{
LOG_PRINT_L2 ( " Encrypting payment id " < < payment_id8 ) ;
crypto : : public_key view_key_pub = get_destination_view_key_pub ( destinations , change_addr ) ;
if ( view_key_pub = = null_pkey )
{
LOG_ERROR ( " Destinations have to have exactly one output to support encrypted payment ids " ) ;
return false ;
}
if ( ! hwdev . encrypt_payment_id ( payment_id8 , view_key_pub , tx_key ) )
{
LOG_ERROR ( " Failed to encrypt payment id " ) ;
return false ;
}
std : : string extra_nonce ;
set_encrypted_payment_id_to_tx_extra_nonce ( extra_nonce , payment_id8 ) ;
remove_field_from_tx_extra ( tx . extra , typeid ( tx_extra_nonce ) ) ;
if ( ! add_extra_nonce_to_tx_extra ( tx . extra , extra_nonce ) )
{
LOG_ERROR ( " Failed to add encrypted payment id to tx extra " ) ;
return false ;
}
LOG_PRINT_L1 ( " Encrypted payment ID: " < < payment_id8 ) ;
add_dummy_payment_id = false ;
}
else if ( get_payment_id_from_tx_extra_nonce ( extra_nonce . nonce , payment_id ) )
{
add_dummy_payment_id = false ;
}
}
// we don't add one if we've got more than the usual 1 destination plus change
if ( destinations . size ( ) > 2 )
add_dummy_payment_id = false ;
if ( add_dummy_payment_id )
{
// if we have neither long nor short payment id, add a dummy short one,
// this should end up being the vast majority of txes as time goes on
std : : string extra_nonce ;
crypto : : hash8 payment_id8 = null_hash8 ;
crypto : : public_key view_key_pub = get_destination_view_key_pub ( destinations , change_addr ) ;
if ( view_key_pub = = null_pkey )
{
LOG_ERROR ( " Failed to get key to encrypt dummy payment id with " ) ;
}
else
{
hwdev . encrypt_payment_id ( payment_id8 , view_key_pub , tx_key ) ;
set_encrypted_payment_id_to_tx_extra_nonce ( extra_nonce , payment_id8 ) ;
if ( ! add_extra_nonce_to_tx_extra ( tx . extra , extra_nonce ) )
{
LOG_ERROR ( " Failed to add dummy encrypted payment id to tx extra " ) ;
// continue anyway
}
}
}
}
else
{
MWARNING ( " Failed to parse tx extra " ) ;
tx_extra_fields . clear ( ) ;
}
struct input_generation_context_data
{
keypair in_ephemeral ;
} ;
std : : vector < input_generation_context_data > in_contexts ;
uint64_t summary_inputs_money = 0 ;
//fill inputs
int idx = - 1 ;
for ( const tx_source_entry & src_entr : sources )
{
+ + idx ;
if ( src_entr . real_output > = src_entr . outputs . size ( ) )
{
LOG_ERROR ( " real_output index ( " < < src_entr . real_output < < " )bigger than output_keys.size()= " < < src_entr . outputs . size ( ) ) ;
return false ;
}
summary_inputs_money + = src_entr . amount ;
//key_derivation recv_derivation;
in_contexts . push_back ( input_generation_context_data ( ) ) ;
keypair & in_ephemeral = in_contexts . back ( ) . in_ephemeral ;
crypto : : key_image img ;
const auto & out_key = reinterpret_cast < const crypto : : public_key & > ( src_entr . outputs [ src_entr . real_output ] . second . dest ) ;
if ( ! generate_key_image_helper ( sender_account_keys , subaddresses , out_key , src_entr . real_out_tx_key , src_entr . real_out_additional_tx_keys , src_entr . real_output_in_tx_index , in_ephemeral , img , hwdev ) )
{
LOG_ERROR ( " Key image generation failed! " ) ;
return false ;
}
//check that derivated key is equal with real output key (if non multisig)
if ( ! msout & & ! ( in_ephemeral . pub = = src_entr . outputs [ src_entr . real_output ] . second . dest ) )
{
LOG_ERROR ( " derived public key mismatch with output public key at index " < < idx < < " , real out " < < src_entr . real_output < < " ! " < < ENDL < < " derived_key: "
< < string_tools : : pod_to_hex ( in_ephemeral . pub ) < < ENDL < < " real output_public_key: "
< < string_tools : : pod_to_hex ( src_entr . outputs [ src_entr . real_output ] . second . dest ) ) ;
LOG_ERROR ( " amount " < < src_entr . amount < < " , rct " < < src_entr . rct ) ;
LOG_ERROR ( " tx pubkey " < < src_entr . real_out_tx_key < < " , real_output_in_tx_index " < < src_entr . real_output_in_tx_index ) ;
return false ;
}
//put key image into tx input
txin_to_key input_to_key ;
input_to_key . amount = src_entr . amount ;
Add N/N multisig tx generation and signing
Scheme by luigi1111:
Multisig for RingCT on Monero
2 of 2
User A (coordinator):
Spendkey b,B
Viewkey a,A (shared)
User B:
Spendkey c,C
Viewkey a,A (shared)
Public Address: C+B, A
Both have their own watch only wallet via C+B, a
A will coordinate spending process (though B could easily as well, coordinator is more needed for more participants)
A and B watch for incoming outputs
B creates "half" key images for discovered output D:
I2_D = (Hs(aR)+c) * Hp(D)
B also creates 1.5 random keypairs (one scalar and 2 pubkeys; one on base G and one on base Hp(D)) for each output, storing the scalar(k) (linked to D),
and sending the pubkeys with I2_D.
A also creates "half" key images:
I1_D = (Hs(aR)+b) * Hp(D)
Then I_D = I1_D + I2_D
Having I_D allows A to check spent status of course, but more importantly allows A to actually build a transaction prefix (and thus transaction).
A builds the transaction until most of the way through MLSAG_Gen, adding the 2 pubkeys (per input) provided with I2_D
to his own generated ones where they are needed (secret row L, R).
At this point, A has a mostly completed transaction (but with an invalid/incomplete signature). A sends over the tx and includes r,
which allows B (with the recipient's address) to verify the destination and amount (by reconstructing the stealth address and decoding ecdhInfo).
B then finishes the signature by computing ss[secret_index][0] = ss[secret_index][0] + k - cc[secret_index]*c (secret indices need to be passed as well).
B can then broadcast the tx, or send it back to A for broadcasting. Once B has completed the signing (and verified the tx to be valid), he can add the full I_D
to his cache, allowing him to verify spent status as well.
NOTE:
A and B *must* present key A and B to each other with a valid signature proving they know a and b respectively.
Otherwise, trickery like the following becomes possible:
A creates viewkey a,A, spendkey b,B, and sends a,A,B to B.
B creates a fake key C = zG - B. B sends C back to A.
The combined spendkey C+B then equals zG, allowing B to spend funds at any time!
The signature fixes this, because B does not know a c corresponding to C (and thus can't produce a signature).
2 of 3
User A (coordinator)
Shared viewkey a,A
"spendkey" j,J
User B
"spendkey" k,K
User C
"spendkey" m,M
A collects K and M from B and C
B collects J and M from A and C
C collects J and K from A and B
A computes N = nG, n = Hs(jK)
A computes O = oG, o = Hs(jM)
B anc C compute P = pG, p = Hs(kM) || Hs(mK)
B and C can also compute N and O respectively if they wish to be able to coordinate
Address: N+O+P, A
The rest follows as above. The coordinator possesses 2 of 3 needed keys; he can get the other
needed part of the signature/key images from either of the other two.
Alternatively, if secure communication exists between parties:
A gives j to B
B gives k to C
C gives m to A
Address: J+K+M, A
3 of 3
Identical to 2 of 2, except the coordinator must collect the key images from both of the others.
The transaction must also be passed an additional hop: A -> B -> C (or A -> C -> B), who can then broadcast it
or send it back to A.
N-1 of N
Generally the same as 2 of 3, except participants need to be arranged in a ring to pass their keys around
(using either the secure or insecure method).
For example (ignoring viewkey so letters line up):
[4 of 5]
User: spendkey
A: a
B: b
C: c
D: d
E: e
a -> B, b -> C, c -> D, d -> E, e -> A
Order of signing does not matter, it just must reach n-1 users. A "remaining keys" list must be passed around with
the transaction so the signers know if they should use 1 or both keys.
Collecting key image parts becomes a little messy, but basically every wallet sends over both of their parts with a tag for each.
Thia way the coordinating wallet can keep track of which images have been added and which wallet they come from. Reasoning:
1. The key images must be added only once (coordinator will get key images for key a from both A and B, he must add only one to get the proper key actual key image)
2. The coordinator must keep track of which helper pubkeys came from which wallet (discussed in 2 of 2 section). The coordinator
must choose only one set to use, then include his choice in the "remaining keys" list so the other wallets know which of their keys to use.
You can generalize it further to N-2 of N or even M of N, but I'm not sure there's legitimate demand to justify the complexity. It might
also be straightforward enough to support with minimal changes from N-1 format.
You basically just give each user additional keys for each additional "-1" you desire. N-2 would be 3 keys per user, N-3 4 keys, etc.
The process is somewhat cumbersome:
To create a N/N multisig wallet:
- each participant creates a normal wallet
- each participant runs "prepare_multisig", and sends the resulting string to every other participant
- each participant runs "make_multisig N A B C D...", with N being the threshold and A B C D... being the strings received from other participants (the threshold must currently equal N)
As txes are received, participants' wallets will need to synchronize so that those new outputs may be spent:
- each participant runs "export_multisig FILENAME", and sends the FILENAME file to every other participant
- each participant runs "import_multisig A B C D...", with A B C D... being the filenames received from other participants
Then, a transaction may be initiated:
- one of the participants runs "transfer ADDRESS AMOUNT"
- this partly signed transaction will be written to the "multisig_monero_tx" file
- the initiator sends this file to another participant
- that other participant runs "sign_multisig multisig_monero_tx"
- the resulting transaction is written to the "multisig_monero_tx" file again
- if the threshold was not reached, the file must be sent to another participant, until enough have signed
- the last participant to sign runs "submit_multisig multisig_monero_tx" to relay the transaction to the Monero network
7 years ago
input_to_key . k_image = msout ? rct : : rct2ki ( src_entr . multisig_kLRki . ki ) : img ;
//fill outputs array and use relative offsets
for ( const tx_source_entry : : output_entry & out_entry : src_entr . outputs )
input_to_key . key_offsets . push_back ( out_entry . first ) ;
input_to_key . key_offsets = absolute_output_offsets_to_relative ( input_to_key . key_offsets ) ;
tx . vin . push_back ( input_to_key ) ;
}
if ( shuffle_outs )
{
std : : shuffle ( destinations . begin ( ) , destinations . end ( ) , crypto : : random_device { } ) ;
}
// sort ins by their key image
std : : vector < size_t > ins_order ( sources . size ( ) ) ;
for ( size_t n = 0 ; n < sources . size ( ) ; + + n )
ins_order [ n ] = n ;
std : : sort ( ins_order . begin ( ) , ins_order . end ( ) , [ & ] ( const size_t i0 , const size_t i1 ) {
const txin_to_key & tk0 = boost : : get < txin_to_key > ( tx . vin [ i0 ] ) ;
const txin_to_key & tk1 = boost : : get < txin_to_key > ( tx . vin [ i1 ] ) ;
return memcmp ( & tk0 . k_image , & tk1 . k_image , sizeof ( tk0 . k_image ) ) > 0 ;
} ) ;
tools : : apply_permutation ( ins_order , [ & ] ( size_t i0 , size_t i1 ) {
std : : swap ( tx . vin [ i0 ] , tx . vin [ i1 ] ) ;
std : : swap ( in_contexts [ i0 ] , in_contexts [ i1 ] ) ;
std : : swap ( sources [ i0 ] , sources [ i1 ] ) ;
} ) ;
// figure out if we need to make additional tx pubkeys
size_t num_stdaddresses = 0 ;
size_t num_subaddresses = 0 ;
account_public_address single_dest_subaddress ;
Add N/N multisig tx generation and signing
Scheme by luigi1111:
Multisig for RingCT on Monero
2 of 2
User A (coordinator):
Spendkey b,B
Viewkey a,A (shared)
User B:
Spendkey c,C
Viewkey a,A (shared)
Public Address: C+B, A
Both have their own watch only wallet via C+B, a
A will coordinate spending process (though B could easily as well, coordinator is more needed for more participants)
A and B watch for incoming outputs
B creates "half" key images for discovered output D:
I2_D = (Hs(aR)+c) * Hp(D)
B also creates 1.5 random keypairs (one scalar and 2 pubkeys; one on base G and one on base Hp(D)) for each output, storing the scalar(k) (linked to D),
and sending the pubkeys with I2_D.
A also creates "half" key images:
I1_D = (Hs(aR)+b) * Hp(D)
Then I_D = I1_D + I2_D
Having I_D allows A to check spent status of course, but more importantly allows A to actually build a transaction prefix (and thus transaction).
A builds the transaction until most of the way through MLSAG_Gen, adding the 2 pubkeys (per input) provided with I2_D
to his own generated ones where they are needed (secret row L, R).
At this point, A has a mostly completed transaction (but with an invalid/incomplete signature). A sends over the tx and includes r,
which allows B (with the recipient's address) to verify the destination and amount (by reconstructing the stealth address and decoding ecdhInfo).
B then finishes the signature by computing ss[secret_index][0] = ss[secret_index][0] + k - cc[secret_index]*c (secret indices need to be passed as well).
B can then broadcast the tx, or send it back to A for broadcasting. Once B has completed the signing (and verified the tx to be valid), he can add the full I_D
to his cache, allowing him to verify spent status as well.
NOTE:
A and B *must* present key A and B to each other with a valid signature proving they know a and b respectively.
Otherwise, trickery like the following becomes possible:
A creates viewkey a,A, spendkey b,B, and sends a,A,B to B.
B creates a fake key C = zG - B. B sends C back to A.
The combined spendkey C+B then equals zG, allowing B to spend funds at any time!
The signature fixes this, because B does not know a c corresponding to C (and thus can't produce a signature).
2 of 3
User A (coordinator)
Shared viewkey a,A
"spendkey" j,J
User B
"spendkey" k,K
User C
"spendkey" m,M
A collects K and M from B and C
B collects J and M from A and C
C collects J and K from A and B
A computes N = nG, n = Hs(jK)
A computes O = oG, o = Hs(jM)
B anc C compute P = pG, p = Hs(kM) || Hs(mK)
B and C can also compute N and O respectively if they wish to be able to coordinate
Address: N+O+P, A
The rest follows as above. The coordinator possesses 2 of 3 needed keys; he can get the other
needed part of the signature/key images from either of the other two.
Alternatively, if secure communication exists between parties:
A gives j to B
B gives k to C
C gives m to A
Address: J+K+M, A
3 of 3
Identical to 2 of 2, except the coordinator must collect the key images from both of the others.
The transaction must also be passed an additional hop: A -> B -> C (or A -> C -> B), who can then broadcast it
or send it back to A.
N-1 of N
Generally the same as 2 of 3, except participants need to be arranged in a ring to pass their keys around
(using either the secure or insecure method).
For example (ignoring viewkey so letters line up):
[4 of 5]
User: spendkey
A: a
B: b
C: c
D: d
E: e
a -> B, b -> C, c -> D, d -> E, e -> A
Order of signing does not matter, it just must reach n-1 users. A "remaining keys" list must be passed around with
the transaction so the signers know if they should use 1 or both keys.
Collecting key image parts becomes a little messy, but basically every wallet sends over both of their parts with a tag for each.
Thia way the coordinating wallet can keep track of which images have been added and which wallet they come from. Reasoning:
1. The key images must be added only once (coordinator will get key images for key a from both A and B, he must add only one to get the proper key actual key image)
2. The coordinator must keep track of which helper pubkeys came from which wallet (discussed in 2 of 2 section). The coordinator
must choose only one set to use, then include his choice in the "remaining keys" list so the other wallets know which of their keys to use.
You can generalize it further to N-2 of N or even M of N, but I'm not sure there's legitimate demand to justify the complexity. It might
also be straightforward enough to support with minimal changes from N-1 format.
You basically just give each user additional keys for each additional "-1" you desire. N-2 would be 3 keys per user, N-3 4 keys, etc.
The process is somewhat cumbersome:
To create a N/N multisig wallet:
- each participant creates a normal wallet
- each participant runs "prepare_multisig", and sends the resulting string to every other participant
- each participant runs "make_multisig N A B C D...", with N being the threshold and A B C D... being the strings received from other participants (the threshold must currently equal N)
As txes are received, participants' wallets will need to synchronize so that those new outputs may be spent:
- each participant runs "export_multisig FILENAME", and sends the FILENAME file to every other participant
- each participant runs "import_multisig A B C D...", with A B C D... being the filenames received from other participants
Then, a transaction may be initiated:
- one of the participants runs "transfer ADDRESS AMOUNT"
- this partly signed transaction will be written to the "multisig_monero_tx" file
- the initiator sends this file to another participant
- that other participant runs "sign_multisig multisig_monero_tx"
- the resulting transaction is written to the "multisig_monero_tx" file again
- if the threshold was not reached, the file must be sent to another participant, until enough have signed
- the last participant to sign runs "submit_multisig multisig_monero_tx" to relay the transaction to the Monero network
7 years ago
classify_addresses ( destinations , change_addr , num_stdaddresses , num_subaddresses , single_dest_subaddress ) ;
// if this is a single-destination transfer to a subaddress, we set the tx pubkey to R=s*D
if ( num_stdaddresses = = 0 & & num_subaddresses = = 1 )
{
txkey_pub = rct : : rct2pk ( hwdev . scalarmultKey ( rct : : pk2rct ( single_dest_subaddress . m_spend_public_key ) , rct : : sk2rct ( tx_key ) ) ) ;
}
else
{
txkey_pub = rct : : rct2pk ( hwdev . scalarmultBase ( rct : : sk2rct ( tx_key ) ) ) ;
}
remove_field_from_tx_extra ( tx . extra , typeid ( tx_extra_pub_key ) ) ;
Add N/N multisig tx generation and signing
Scheme by luigi1111:
Multisig for RingCT on Monero
2 of 2
User A (coordinator):
Spendkey b,B
Viewkey a,A (shared)
User B:
Spendkey c,C
Viewkey a,A (shared)
Public Address: C+B, A
Both have their own watch only wallet via C+B, a
A will coordinate spending process (though B could easily as well, coordinator is more needed for more participants)
A and B watch for incoming outputs
B creates "half" key images for discovered output D:
I2_D = (Hs(aR)+c) * Hp(D)
B also creates 1.5 random keypairs (one scalar and 2 pubkeys; one on base G and one on base Hp(D)) for each output, storing the scalar(k) (linked to D),
and sending the pubkeys with I2_D.
A also creates "half" key images:
I1_D = (Hs(aR)+b) * Hp(D)
Then I_D = I1_D + I2_D
Having I_D allows A to check spent status of course, but more importantly allows A to actually build a transaction prefix (and thus transaction).
A builds the transaction until most of the way through MLSAG_Gen, adding the 2 pubkeys (per input) provided with I2_D
to his own generated ones where they are needed (secret row L, R).
At this point, A has a mostly completed transaction (but with an invalid/incomplete signature). A sends over the tx and includes r,
which allows B (with the recipient's address) to verify the destination and amount (by reconstructing the stealth address and decoding ecdhInfo).
B then finishes the signature by computing ss[secret_index][0] = ss[secret_index][0] + k - cc[secret_index]*c (secret indices need to be passed as well).
B can then broadcast the tx, or send it back to A for broadcasting. Once B has completed the signing (and verified the tx to be valid), he can add the full I_D
to his cache, allowing him to verify spent status as well.
NOTE:
A and B *must* present key A and B to each other with a valid signature proving they know a and b respectively.
Otherwise, trickery like the following becomes possible:
A creates viewkey a,A, spendkey b,B, and sends a,A,B to B.
B creates a fake key C = zG - B. B sends C back to A.
The combined spendkey C+B then equals zG, allowing B to spend funds at any time!
The signature fixes this, because B does not know a c corresponding to C (and thus can't produce a signature).
2 of 3
User A (coordinator)
Shared viewkey a,A
"spendkey" j,J
User B
"spendkey" k,K
User C
"spendkey" m,M
A collects K and M from B and C
B collects J and M from A and C
C collects J and K from A and B
A computes N = nG, n = Hs(jK)
A computes O = oG, o = Hs(jM)
B anc C compute P = pG, p = Hs(kM) || Hs(mK)
B and C can also compute N and O respectively if they wish to be able to coordinate
Address: N+O+P, A
The rest follows as above. The coordinator possesses 2 of 3 needed keys; he can get the other
needed part of the signature/key images from either of the other two.
Alternatively, if secure communication exists between parties:
A gives j to B
B gives k to C
C gives m to A
Address: J+K+M, A
3 of 3
Identical to 2 of 2, except the coordinator must collect the key images from both of the others.
The transaction must also be passed an additional hop: A -> B -> C (or A -> C -> B), who can then broadcast it
or send it back to A.
N-1 of N
Generally the same as 2 of 3, except participants need to be arranged in a ring to pass their keys around
(using either the secure or insecure method).
For example (ignoring viewkey so letters line up):
[4 of 5]
User: spendkey
A: a
B: b
C: c
D: d
E: e
a -> B, b -> C, c -> D, d -> E, e -> A
Order of signing does not matter, it just must reach n-1 users. A "remaining keys" list must be passed around with
the transaction so the signers know if they should use 1 or both keys.
Collecting key image parts becomes a little messy, but basically every wallet sends over both of their parts with a tag for each.
Thia way the coordinating wallet can keep track of which images have been added and which wallet they come from. Reasoning:
1. The key images must be added only once (coordinator will get key images for key a from both A and B, he must add only one to get the proper key actual key image)
2. The coordinator must keep track of which helper pubkeys came from which wallet (discussed in 2 of 2 section). The coordinator
must choose only one set to use, then include his choice in the "remaining keys" list so the other wallets know which of their keys to use.
You can generalize it further to N-2 of N or even M of N, but I'm not sure there's legitimate demand to justify the complexity. It might
also be straightforward enough to support with minimal changes from N-1 format.
You basically just give each user additional keys for each additional "-1" you desire. N-2 would be 3 keys per user, N-3 4 keys, etc.
The process is somewhat cumbersome:
To create a N/N multisig wallet:
- each participant creates a normal wallet
- each participant runs "prepare_multisig", and sends the resulting string to every other participant
- each participant runs "make_multisig N A B C D...", with N being the threshold and A B C D... being the strings received from other participants (the threshold must currently equal N)
As txes are received, participants' wallets will need to synchronize so that those new outputs may be spent:
- each participant runs "export_multisig FILENAME", and sends the FILENAME file to every other participant
- each participant runs "import_multisig A B C D...", with A B C D... being the filenames received from other participants
Then, a transaction may be initiated:
- one of the participants runs "transfer ADDRESS AMOUNT"
- this partly signed transaction will be written to the "multisig_monero_tx" file
- the initiator sends this file to another participant
- that other participant runs "sign_multisig multisig_monero_tx"
- the resulting transaction is written to the "multisig_monero_tx" file again
- if the threshold was not reached, the file must be sent to another participant, until enough have signed
- the last participant to sign runs "submit_multisig multisig_monero_tx" to relay the transaction to the Monero network
7 years ago
add_tx_pub_key_to_extra ( tx , txkey_pub ) ;
std : : vector < crypto : : public_key > additional_tx_public_keys ;
// we don't need to include additional tx keys if:
// - all the destinations are standard addresses
// - there's only one destination which is a subaddress
bool need_additional_txkeys = num_subaddresses > 0 & & ( num_stdaddresses > 0 | | num_subaddresses > 1 ) ;
Add N/N multisig tx generation and signing
Scheme by luigi1111:
Multisig for RingCT on Monero
2 of 2
User A (coordinator):
Spendkey b,B
Viewkey a,A (shared)
User B:
Spendkey c,C
Viewkey a,A (shared)
Public Address: C+B, A
Both have their own watch only wallet via C+B, a
A will coordinate spending process (though B could easily as well, coordinator is more needed for more participants)
A and B watch for incoming outputs
B creates "half" key images for discovered output D:
I2_D = (Hs(aR)+c) * Hp(D)
B also creates 1.5 random keypairs (one scalar and 2 pubkeys; one on base G and one on base Hp(D)) for each output, storing the scalar(k) (linked to D),
and sending the pubkeys with I2_D.
A also creates "half" key images:
I1_D = (Hs(aR)+b) * Hp(D)
Then I_D = I1_D + I2_D
Having I_D allows A to check spent status of course, but more importantly allows A to actually build a transaction prefix (and thus transaction).
A builds the transaction until most of the way through MLSAG_Gen, adding the 2 pubkeys (per input) provided with I2_D
to his own generated ones where they are needed (secret row L, R).
At this point, A has a mostly completed transaction (but with an invalid/incomplete signature). A sends over the tx and includes r,
which allows B (with the recipient's address) to verify the destination and amount (by reconstructing the stealth address and decoding ecdhInfo).
B then finishes the signature by computing ss[secret_index][0] = ss[secret_index][0] + k - cc[secret_index]*c (secret indices need to be passed as well).
B can then broadcast the tx, or send it back to A for broadcasting. Once B has completed the signing (and verified the tx to be valid), he can add the full I_D
to his cache, allowing him to verify spent status as well.
NOTE:
A and B *must* present key A and B to each other with a valid signature proving they know a and b respectively.
Otherwise, trickery like the following becomes possible:
A creates viewkey a,A, spendkey b,B, and sends a,A,B to B.
B creates a fake key C = zG - B. B sends C back to A.
The combined spendkey C+B then equals zG, allowing B to spend funds at any time!
The signature fixes this, because B does not know a c corresponding to C (and thus can't produce a signature).
2 of 3
User A (coordinator)
Shared viewkey a,A
"spendkey" j,J
User B
"spendkey" k,K
User C
"spendkey" m,M
A collects K and M from B and C
B collects J and M from A and C
C collects J and K from A and B
A computes N = nG, n = Hs(jK)
A computes O = oG, o = Hs(jM)
B anc C compute P = pG, p = Hs(kM) || Hs(mK)
B and C can also compute N and O respectively if they wish to be able to coordinate
Address: N+O+P, A
The rest follows as above. The coordinator possesses 2 of 3 needed keys; he can get the other
needed part of the signature/key images from either of the other two.
Alternatively, if secure communication exists between parties:
A gives j to B
B gives k to C
C gives m to A
Address: J+K+M, A
3 of 3
Identical to 2 of 2, except the coordinator must collect the key images from both of the others.
The transaction must also be passed an additional hop: A -> B -> C (or A -> C -> B), who can then broadcast it
or send it back to A.
N-1 of N
Generally the same as 2 of 3, except participants need to be arranged in a ring to pass their keys around
(using either the secure or insecure method).
For example (ignoring viewkey so letters line up):
[4 of 5]
User: spendkey
A: a
B: b
C: c
D: d
E: e
a -> B, b -> C, c -> D, d -> E, e -> A
Order of signing does not matter, it just must reach n-1 users. A "remaining keys" list must be passed around with
the transaction so the signers know if they should use 1 or both keys.
Collecting key image parts becomes a little messy, but basically every wallet sends over both of their parts with a tag for each.
Thia way the coordinating wallet can keep track of which images have been added and which wallet they come from. Reasoning:
1. The key images must be added only once (coordinator will get key images for key a from both A and B, he must add only one to get the proper key actual key image)
2. The coordinator must keep track of which helper pubkeys came from which wallet (discussed in 2 of 2 section). The coordinator
must choose only one set to use, then include his choice in the "remaining keys" list so the other wallets know which of their keys to use.
You can generalize it further to N-2 of N or even M of N, but I'm not sure there's legitimate demand to justify the complexity. It might
also be straightforward enough to support with minimal changes from N-1 format.
You basically just give each user additional keys for each additional "-1" you desire. N-2 would be 3 keys per user, N-3 4 keys, etc.
The process is somewhat cumbersome:
To create a N/N multisig wallet:
- each participant creates a normal wallet
- each participant runs "prepare_multisig", and sends the resulting string to every other participant
- each participant runs "make_multisig N A B C D...", with N being the threshold and A B C D... being the strings received from other participants (the threshold must currently equal N)
As txes are received, participants' wallets will need to synchronize so that those new outputs may be spent:
- each participant runs "export_multisig FILENAME", and sends the FILENAME file to every other participant
- each participant runs "import_multisig A B C D...", with A B C D... being the filenames received from other participants
Then, a transaction may be initiated:
- one of the participants runs "transfer ADDRESS AMOUNT"
- this partly signed transaction will be written to the "multisig_monero_tx" file
- the initiator sends this file to another participant
- that other participant runs "sign_multisig multisig_monero_tx"
- the resulting transaction is written to the "multisig_monero_tx" file again
- if the threshold was not reached, the file must be sent to another participant, until enough have signed
- the last participant to sign runs "submit_multisig multisig_monero_tx" to relay the transaction to the Monero network
7 years ago
if ( need_additional_txkeys )
CHECK_AND_ASSERT_MES ( destinations . size ( ) = = additional_tx_keys . size ( ) , false , " Wrong amount of additional tx keys " ) ;
uint64_t summary_outs_money = 0 ;
//fill outputs
size_t output_index = 0 ;
for ( const tx_destination_entry & dst_entr : destinations )
{
CHECK_AND_ASSERT_MES ( dst_entr . amount > 0 | | tx . version > 1 , false , " Destination with wrong amount: " < < dst_entr . amount ) ;
crypto : : public_key out_eph_public_key ;
hwdev . generate_output_ephemeral_keys ( tx . version , sender_account_keys , txkey_pub , tx_key ,
dst_entr , change_addr , output_index ,
need_additional_txkeys , additional_tx_keys ,
additional_tx_public_keys , amount_keys , out_eph_public_key ) ;
tx_out out ;
out . amount = dst_entr . amount ;
txout_to_key tk ;
tk . key = out_eph_public_key ;
out . target = tk ;
tx . vout . push_back ( out ) ;
output_index + + ;
summary_outs_money + = dst_entr . amount ;
}
Add N/N multisig tx generation and signing
Scheme by luigi1111:
Multisig for RingCT on Monero
2 of 2
User A (coordinator):
Spendkey b,B
Viewkey a,A (shared)
User B:
Spendkey c,C
Viewkey a,A (shared)
Public Address: C+B, A
Both have their own watch only wallet via C+B, a
A will coordinate spending process (though B could easily as well, coordinator is more needed for more participants)
A and B watch for incoming outputs
B creates "half" key images for discovered output D:
I2_D = (Hs(aR)+c) * Hp(D)
B also creates 1.5 random keypairs (one scalar and 2 pubkeys; one on base G and one on base Hp(D)) for each output, storing the scalar(k) (linked to D),
and sending the pubkeys with I2_D.
A also creates "half" key images:
I1_D = (Hs(aR)+b) * Hp(D)
Then I_D = I1_D + I2_D
Having I_D allows A to check spent status of course, but more importantly allows A to actually build a transaction prefix (and thus transaction).
A builds the transaction until most of the way through MLSAG_Gen, adding the 2 pubkeys (per input) provided with I2_D
to his own generated ones where they are needed (secret row L, R).
At this point, A has a mostly completed transaction (but with an invalid/incomplete signature). A sends over the tx and includes r,
which allows B (with the recipient's address) to verify the destination and amount (by reconstructing the stealth address and decoding ecdhInfo).
B then finishes the signature by computing ss[secret_index][0] = ss[secret_index][0] + k - cc[secret_index]*c (secret indices need to be passed as well).
B can then broadcast the tx, or send it back to A for broadcasting. Once B has completed the signing (and verified the tx to be valid), he can add the full I_D
to his cache, allowing him to verify spent status as well.
NOTE:
A and B *must* present key A and B to each other with a valid signature proving they know a and b respectively.
Otherwise, trickery like the following becomes possible:
A creates viewkey a,A, spendkey b,B, and sends a,A,B to B.
B creates a fake key C = zG - B. B sends C back to A.
The combined spendkey C+B then equals zG, allowing B to spend funds at any time!
The signature fixes this, because B does not know a c corresponding to C (and thus can't produce a signature).
2 of 3
User A (coordinator)
Shared viewkey a,A
"spendkey" j,J
User B
"spendkey" k,K
User C
"spendkey" m,M
A collects K and M from B and C
B collects J and M from A and C
C collects J and K from A and B
A computes N = nG, n = Hs(jK)
A computes O = oG, o = Hs(jM)
B anc C compute P = pG, p = Hs(kM) || Hs(mK)
B and C can also compute N and O respectively if they wish to be able to coordinate
Address: N+O+P, A
The rest follows as above. The coordinator possesses 2 of 3 needed keys; he can get the other
needed part of the signature/key images from either of the other two.
Alternatively, if secure communication exists between parties:
A gives j to B
B gives k to C
C gives m to A
Address: J+K+M, A
3 of 3
Identical to 2 of 2, except the coordinator must collect the key images from both of the others.
The transaction must also be passed an additional hop: A -> B -> C (or A -> C -> B), who can then broadcast it
or send it back to A.
N-1 of N
Generally the same as 2 of 3, except participants need to be arranged in a ring to pass their keys around
(using either the secure or insecure method).
For example (ignoring viewkey so letters line up):
[4 of 5]
User: spendkey
A: a
B: b
C: c
D: d
E: e
a -> B, b -> C, c -> D, d -> E, e -> A
Order of signing does not matter, it just must reach n-1 users. A "remaining keys" list must be passed around with
the transaction so the signers know if they should use 1 or both keys.
Collecting key image parts becomes a little messy, but basically every wallet sends over both of their parts with a tag for each.
Thia way the coordinating wallet can keep track of which images have been added and which wallet they come from. Reasoning:
1. The key images must be added only once (coordinator will get key images for key a from both A and B, he must add only one to get the proper key actual key image)
2. The coordinator must keep track of which helper pubkeys came from which wallet (discussed in 2 of 2 section). The coordinator
must choose only one set to use, then include his choice in the "remaining keys" list so the other wallets know which of their keys to use.
You can generalize it further to N-2 of N or even M of N, but I'm not sure there's legitimate demand to justify the complexity. It might
also be straightforward enough to support with minimal changes from N-1 format.
You basically just give each user additional keys for each additional "-1" you desire. N-2 would be 3 keys per user, N-3 4 keys, etc.
The process is somewhat cumbersome:
To create a N/N multisig wallet:
- each participant creates a normal wallet
- each participant runs "prepare_multisig", and sends the resulting string to every other participant
- each participant runs "make_multisig N A B C D...", with N being the threshold and A B C D... being the strings received from other participants (the threshold must currently equal N)
As txes are received, participants' wallets will need to synchronize so that those new outputs may be spent:
- each participant runs "export_multisig FILENAME", and sends the FILENAME file to every other participant
- each participant runs "import_multisig A B C D...", with A B C D... being the filenames received from other participants
Then, a transaction may be initiated:
- one of the participants runs "transfer ADDRESS AMOUNT"
- this partly signed transaction will be written to the "multisig_monero_tx" file
- the initiator sends this file to another participant
- that other participant runs "sign_multisig multisig_monero_tx"
- the resulting transaction is written to the "multisig_monero_tx" file again
- if the threshold was not reached, the file must be sent to another participant, until enough have signed
- the last participant to sign runs "submit_multisig multisig_monero_tx" to relay the transaction to the Monero network
7 years ago
CHECK_AND_ASSERT_MES ( additional_tx_public_keys . size ( ) = = additional_tx_keys . size ( ) , false , " Internal error creating additional public keys " ) ;
remove_field_from_tx_extra ( tx . extra , typeid ( tx_extra_additional_pub_keys ) ) ;
Add N/N multisig tx generation and signing
Scheme by luigi1111:
Multisig for RingCT on Monero
2 of 2
User A (coordinator):
Spendkey b,B
Viewkey a,A (shared)
User B:
Spendkey c,C
Viewkey a,A (shared)
Public Address: C+B, A
Both have their own watch only wallet via C+B, a
A will coordinate spending process (though B could easily as well, coordinator is more needed for more participants)
A and B watch for incoming outputs
B creates "half" key images for discovered output D:
I2_D = (Hs(aR)+c) * Hp(D)
B also creates 1.5 random keypairs (one scalar and 2 pubkeys; one on base G and one on base Hp(D)) for each output, storing the scalar(k) (linked to D),
and sending the pubkeys with I2_D.
A also creates "half" key images:
I1_D = (Hs(aR)+b) * Hp(D)
Then I_D = I1_D + I2_D
Having I_D allows A to check spent status of course, but more importantly allows A to actually build a transaction prefix (and thus transaction).
A builds the transaction until most of the way through MLSAG_Gen, adding the 2 pubkeys (per input) provided with I2_D
to his own generated ones where they are needed (secret row L, R).
At this point, A has a mostly completed transaction (but with an invalid/incomplete signature). A sends over the tx and includes r,
which allows B (with the recipient's address) to verify the destination and amount (by reconstructing the stealth address and decoding ecdhInfo).
B then finishes the signature by computing ss[secret_index][0] = ss[secret_index][0] + k - cc[secret_index]*c (secret indices need to be passed as well).
B can then broadcast the tx, or send it back to A for broadcasting. Once B has completed the signing (and verified the tx to be valid), he can add the full I_D
to his cache, allowing him to verify spent status as well.
NOTE:
A and B *must* present key A and B to each other with a valid signature proving they know a and b respectively.
Otherwise, trickery like the following becomes possible:
A creates viewkey a,A, spendkey b,B, and sends a,A,B to B.
B creates a fake key C = zG - B. B sends C back to A.
The combined spendkey C+B then equals zG, allowing B to spend funds at any time!
The signature fixes this, because B does not know a c corresponding to C (and thus can't produce a signature).
2 of 3
User A (coordinator)
Shared viewkey a,A
"spendkey" j,J
User B
"spendkey" k,K
User C
"spendkey" m,M
A collects K and M from B and C
B collects J and M from A and C
C collects J and K from A and B
A computes N = nG, n = Hs(jK)
A computes O = oG, o = Hs(jM)
B anc C compute P = pG, p = Hs(kM) || Hs(mK)
B and C can also compute N and O respectively if they wish to be able to coordinate
Address: N+O+P, A
The rest follows as above. The coordinator possesses 2 of 3 needed keys; he can get the other
needed part of the signature/key images from either of the other two.
Alternatively, if secure communication exists between parties:
A gives j to B
B gives k to C
C gives m to A
Address: J+K+M, A
3 of 3
Identical to 2 of 2, except the coordinator must collect the key images from both of the others.
The transaction must also be passed an additional hop: A -> B -> C (or A -> C -> B), who can then broadcast it
or send it back to A.
N-1 of N
Generally the same as 2 of 3, except participants need to be arranged in a ring to pass their keys around
(using either the secure or insecure method).
For example (ignoring viewkey so letters line up):
[4 of 5]
User: spendkey
A: a
B: b
C: c
D: d
E: e
a -> B, b -> C, c -> D, d -> E, e -> A
Order of signing does not matter, it just must reach n-1 users. A "remaining keys" list must be passed around with
the transaction so the signers know if they should use 1 or both keys.
Collecting key image parts becomes a little messy, but basically every wallet sends over both of their parts with a tag for each.
Thia way the coordinating wallet can keep track of which images have been added and which wallet they come from. Reasoning:
1. The key images must be added only once (coordinator will get key images for key a from both A and B, he must add only one to get the proper key actual key image)
2. The coordinator must keep track of which helper pubkeys came from which wallet (discussed in 2 of 2 section). The coordinator
must choose only one set to use, then include his choice in the "remaining keys" list so the other wallets know which of their keys to use.
You can generalize it further to N-2 of N or even M of N, but I'm not sure there's legitimate demand to justify the complexity. It might
also be straightforward enough to support with minimal changes from N-1 format.
You basically just give each user additional keys for each additional "-1" you desire. N-2 would be 3 keys per user, N-3 4 keys, etc.
The process is somewhat cumbersome:
To create a N/N multisig wallet:
- each participant creates a normal wallet
- each participant runs "prepare_multisig", and sends the resulting string to every other participant
- each participant runs "make_multisig N A B C D...", with N being the threshold and A B C D... being the strings received from other participants (the threshold must currently equal N)
As txes are received, participants' wallets will need to synchronize so that those new outputs may be spent:
- each participant runs "export_multisig FILENAME", and sends the FILENAME file to every other participant
- each participant runs "import_multisig A B C D...", with A B C D... being the filenames received from other participants
Then, a transaction may be initiated:
- one of the participants runs "transfer ADDRESS AMOUNT"
- this partly signed transaction will be written to the "multisig_monero_tx" file
- the initiator sends this file to another participant
- that other participant runs "sign_multisig multisig_monero_tx"
- the resulting transaction is written to the "multisig_monero_tx" file again
- if the threshold was not reached, the file must be sent to another participant, until enough have signed
- the last participant to sign runs "submit_multisig multisig_monero_tx" to relay the transaction to the Monero network
7 years ago
LOG_PRINT_L2 ( " tx pubkey: " < < txkey_pub ) ;
if ( need_additional_txkeys )
{
LOG_PRINT_L2 ( " additional tx pubkeys: " ) ;
for ( size_t i = 0 ; i < additional_tx_public_keys . size ( ) ; + + i )
LOG_PRINT_L2 ( additional_tx_public_keys [ i ] ) ;
add_additional_tx_pub_keys_to_extra ( tx . extra , additional_tx_public_keys ) ;
}
if ( ! sort_tx_extra ( tx . extra , tx . extra ) )
return false ;
//check money
if ( summary_outs_money > summary_inputs_money )
{
LOG_ERROR ( " Transaction inputs money ( " < < summary_inputs_money < < " ) less than outputs money ( " < < summary_outs_money < < " ) " ) ;
return false ;
}
// check for watch only wallet
bool zero_secret_key = true ;
for ( size_t i = 0 ; i < sizeof ( sender_account_keys . m_spend_secret_key ) ; + + i )
zero_secret_key & = ( sender_account_keys . m_spend_secret_key . data [ i ] = = 0 ) ;
if ( zero_secret_key )
{
MDEBUG ( " Null secret key, skipping signatures " ) ;
}
if ( tx . version = = 1 )
{
//generate ring signatures
crypto : : hash tx_prefix_hash ;
get_transaction_prefix_hash ( tx , tx_prefix_hash ) ;
std : : stringstream ss_ring_s ;
size_t i = 0 ;
for ( const tx_source_entry & src_entr : sources )
{
ss_ring_s < < " pub_keys: " < < ENDL ;
std : : vector < const crypto : : public_key * > keys_ptrs ;
std : : vector < crypto : : public_key > keys ( src_entr . outputs . size ( ) ) ;
size_t ii = 0 ;
for ( const tx_source_entry : : output_entry & o : src_entr . outputs )
{
keys [ ii ] = rct2pk ( o . second . dest ) ;
keys_ptrs . push_back ( & keys [ ii ] ) ;
ss_ring_s < < o . second . dest < < ENDL ;
+ + ii ;
}
tx . signatures . push_back ( std : : vector < crypto : : signature > ( ) ) ;
std : : vector < crypto : : signature > & sigs = tx . signatures . back ( ) ;
sigs . resize ( src_entr . outputs . size ( ) ) ;
if ( ! zero_secret_key )
crypto : : generate_ring_signature ( tx_prefix_hash , boost : : get < txin_to_key > ( tx . vin [ i ] ) . k_image , keys_ptrs , in_contexts [ i ] . in_ephemeral . sec , src_entr . real_output , sigs . data ( ) ) ;
ss_ring_s < < " signatures: " < < ENDL ;
std : : for_each ( sigs . begin ( ) , sigs . end ( ) , [ & ] ( const crypto : : signature & s ) { ss_ring_s < < s < < ENDL ; } ) ;
ss_ring_s < < " prefix_hash: " < < tx_prefix_hash < < ENDL < < " in_ephemeral_key: " < < in_contexts [ i ] . in_ephemeral . sec < < ENDL < < " real_output: " < < src_entr . real_output < < ENDL ;
i + + ;
}
MCINFO ( " construct_tx " , " transaction_created: " < < get_transaction_hash ( tx ) < < ENDL < < obj_to_json_str ( tx ) < < ENDL < < ss_ring_s . str ( ) ) ;
}
else
{
size_t n_total_outs = sources [ 0 ] . outputs . size ( ) ; // only for non-simple rct
// the non-simple version is slightly smaller, but assumes all real inputs
// are on the same index, so can only be used if there just one ring.
bool use_simple_rct = sources . size ( ) > 1 | | rct_config . range_proof_type ! = rct : : RangeProofBorromean ;
if ( ! use_simple_rct )
{
// non simple ringct requires all real inputs to be at the same index for all inputs
for ( const tx_source_entry & src_entr : sources )
{
if ( src_entr . real_output ! = sources . begin ( ) - > real_output )
{
LOG_ERROR ( " All inputs must have the same index for non-simple ringct " ) ;
return false ;
}
}
// enforce same mixin for all outputs
for ( size_t i = 1 ; i < sources . size ( ) ; + + i ) {
if ( n_total_outs ! = sources [ i ] . outputs . size ( ) ) {
LOG_ERROR ( " Non-simple ringct transaction has varying ring size " ) ;
return false ;
}
}
}
uint64_t amount_in = 0 , amount_out = 0 ;
rct : : ctkeyV inSk ;
inSk . reserve ( sources . size ( ) ) ;
// mixRing indexing is done the other way round for simple
rct : : ctkeyM mixRing ( use_simple_rct ? sources . size ( ) : n_total_outs ) ;
rct : : keyV destinations ;
std : : vector < uint64_t > inamounts , outamounts ;
std : : vector < unsigned int > index ;
Add N/N multisig tx generation and signing
Scheme by luigi1111:
Multisig for RingCT on Monero
2 of 2
User A (coordinator):
Spendkey b,B
Viewkey a,A (shared)
User B:
Spendkey c,C
Viewkey a,A (shared)
Public Address: C+B, A
Both have their own watch only wallet via C+B, a
A will coordinate spending process (though B could easily as well, coordinator is more needed for more participants)
A and B watch for incoming outputs
B creates "half" key images for discovered output D:
I2_D = (Hs(aR)+c) * Hp(D)
B also creates 1.5 random keypairs (one scalar and 2 pubkeys; one on base G and one on base Hp(D)) for each output, storing the scalar(k) (linked to D),
and sending the pubkeys with I2_D.
A also creates "half" key images:
I1_D = (Hs(aR)+b) * Hp(D)
Then I_D = I1_D + I2_D
Having I_D allows A to check spent status of course, but more importantly allows A to actually build a transaction prefix (and thus transaction).
A builds the transaction until most of the way through MLSAG_Gen, adding the 2 pubkeys (per input) provided with I2_D
to his own generated ones where they are needed (secret row L, R).
At this point, A has a mostly completed transaction (but with an invalid/incomplete signature). A sends over the tx and includes r,
which allows B (with the recipient's address) to verify the destination and amount (by reconstructing the stealth address and decoding ecdhInfo).
B then finishes the signature by computing ss[secret_index][0] = ss[secret_index][0] + k - cc[secret_index]*c (secret indices need to be passed as well).
B can then broadcast the tx, or send it back to A for broadcasting. Once B has completed the signing (and verified the tx to be valid), he can add the full I_D
to his cache, allowing him to verify spent status as well.
NOTE:
A and B *must* present key A and B to each other with a valid signature proving they know a and b respectively.
Otherwise, trickery like the following becomes possible:
A creates viewkey a,A, spendkey b,B, and sends a,A,B to B.
B creates a fake key C = zG - B. B sends C back to A.
The combined spendkey C+B then equals zG, allowing B to spend funds at any time!
The signature fixes this, because B does not know a c corresponding to C (and thus can't produce a signature).
2 of 3
User A (coordinator)
Shared viewkey a,A
"spendkey" j,J
User B
"spendkey" k,K
User C
"spendkey" m,M
A collects K and M from B and C
B collects J and M from A and C
C collects J and K from A and B
A computes N = nG, n = Hs(jK)
A computes O = oG, o = Hs(jM)
B anc C compute P = pG, p = Hs(kM) || Hs(mK)
B and C can also compute N and O respectively if they wish to be able to coordinate
Address: N+O+P, A
The rest follows as above. The coordinator possesses 2 of 3 needed keys; he can get the other
needed part of the signature/key images from either of the other two.
Alternatively, if secure communication exists between parties:
A gives j to B
B gives k to C
C gives m to A
Address: J+K+M, A
3 of 3
Identical to 2 of 2, except the coordinator must collect the key images from both of the others.
The transaction must also be passed an additional hop: A -> B -> C (or A -> C -> B), who can then broadcast it
or send it back to A.
N-1 of N
Generally the same as 2 of 3, except participants need to be arranged in a ring to pass their keys around
(using either the secure or insecure method).
For example (ignoring viewkey so letters line up):
[4 of 5]
User: spendkey
A: a
B: b
C: c
D: d
E: e
a -> B, b -> C, c -> D, d -> E, e -> A
Order of signing does not matter, it just must reach n-1 users. A "remaining keys" list must be passed around with
the transaction so the signers know if they should use 1 or both keys.
Collecting key image parts becomes a little messy, but basically every wallet sends over both of their parts with a tag for each.
Thia way the coordinating wallet can keep track of which images have been added and which wallet they come from. Reasoning:
1. The key images must be added only once (coordinator will get key images for key a from both A and B, he must add only one to get the proper key actual key image)
2. The coordinator must keep track of which helper pubkeys came from which wallet (discussed in 2 of 2 section). The coordinator
must choose only one set to use, then include his choice in the "remaining keys" list so the other wallets know which of their keys to use.
You can generalize it further to N-2 of N or even M of N, but I'm not sure there's legitimate demand to justify the complexity. It might
also be straightforward enough to support with minimal changes from N-1 format.
You basically just give each user additional keys for each additional "-1" you desire. N-2 would be 3 keys per user, N-3 4 keys, etc.
The process is somewhat cumbersome:
To create a N/N multisig wallet:
- each participant creates a normal wallet
- each participant runs "prepare_multisig", and sends the resulting string to every other participant
- each participant runs "make_multisig N A B C D...", with N being the threshold and A B C D... being the strings received from other participants (the threshold must currently equal N)
As txes are received, participants' wallets will need to synchronize so that those new outputs may be spent:
- each participant runs "export_multisig FILENAME", and sends the FILENAME file to every other participant
- each participant runs "import_multisig A B C D...", with A B C D... being the filenames received from other participants
Then, a transaction may be initiated:
- one of the participants runs "transfer ADDRESS AMOUNT"
- this partly signed transaction will be written to the "multisig_monero_tx" file
- the initiator sends this file to another participant
- that other participant runs "sign_multisig multisig_monero_tx"
- the resulting transaction is written to the "multisig_monero_tx" file again
- if the threshold was not reached, the file must be sent to another participant, until enough have signed
- the last participant to sign runs "submit_multisig multisig_monero_tx" to relay the transaction to the Monero network
7 years ago
std : : vector < rct : : multisig_kLRki > kLRki ;
for ( size_t i = 0 ; i < sources . size ( ) ; + + i )
{
rct : : ctkey ctkey ;
amount_in + = sources [ i ] . amount ;
inamounts . push_back ( sources [ i ] . amount ) ;
index . push_back ( sources [ i ] . real_output ) ;
// inSk: (secret key, mask)
ctkey . dest = rct : : sk2rct ( in_contexts [ i ] . in_ephemeral . sec ) ;
ctkey . mask = sources [ i ] . mask ;
inSk . push_back ( ctkey ) ;
memwipe ( & ctkey , sizeof ( rct : : ctkey ) ) ;
// inPk: (public key, commitment)
// will be done when filling in mixRing
Add N/N multisig tx generation and signing
Scheme by luigi1111:
Multisig for RingCT on Monero
2 of 2
User A (coordinator):
Spendkey b,B
Viewkey a,A (shared)
User B:
Spendkey c,C
Viewkey a,A (shared)
Public Address: C+B, A
Both have their own watch only wallet via C+B, a
A will coordinate spending process (though B could easily as well, coordinator is more needed for more participants)
A and B watch for incoming outputs
B creates "half" key images for discovered output D:
I2_D = (Hs(aR)+c) * Hp(D)
B also creates 1.5 random keypairs (one scalar and 2 pubkeys; one on base G and one on base Hp(D)) for each output, storing the scalar(k) (linked to D),
and sending the pubkeys with I2_D.
A also creates "half" key images:
I1_D = (Hs(aR)+b) * Hp(D)
Then I_D = I1_D + I2_D
Having I_D allows A to check spent status of course, but more importantly allows A to actually build a transaction prefix (and thus transaction).
A builds the transaction until most of the way through MLSAG_Gen, adding the 2 pubkeys (per input) provided with I2_D
to his own generated ones where they are needed (secret row L, R).
At this point, A has a mostly completed transaction (but with an invalid/incomplete signature). A sends over the tx and includes r,
which allows B (with the recipient's address) to verify the destination and amount (by reconstructing the stealth address and decoding ecdhInfo).
B then finishes the signature by computing ss[secret_index][0] = ss[secret_index][0] + k - cc[secret_index]*c (secret indices need to be passed as well).
B can then broadcast the tx, or send it back to A for broadcasting. Once B has completed the signing (and verified the tx to be valid), he can add the full I_D
to his cache, allowing him to verify spent status as well.
NOTE:
A and B *must* present key A and B to each other with a valid signature proving they know a and b respectively.
Otherwise, trickery like the following becomes possible:
A creates viewkey a,A, spendkey b,B, and sends a,A,B to B.
B creates a fake key C = zG - B. B sends C back to A.
The combined spendkey C+B then equals zG, allowing B to spend funds at any time!
The signature fixes this, because B does not know a c corresponding to C (and thus can't produce a signature).
2 of 3
User A (coordinator)
Shared viewkey a,A
"spendkey" j,J
User B
"spendkey" k,K
User C
"spendkey" m,M
A collects K and M from B and C
B collects J and M from A and C
C collects J and K from A and B
A computes N = nG, n = Hs(jK)
A computes O = oG, o = Hs(jM)
B anc C compute P = pG, p = Hs(kM) || Hs(mK)
B and C can also compute N and O respectively if they wish to be able to coordinate
Address: N+O+P, A
The rest follows as above. The coordinator possesses 2 of 3 needed keys; he can get the other
needed part of the signature/key images from either of the other two.
Alternatively, if secure communication exists between parties:
A gives j to B
B gives k to C
C gives m to A
Address: J+K+M, A
3 of 3
Identical to 2 of 2, except the coordinator must collect the key images from both of the others.
The transaction must also be passed an additional hop: A -> B -> C (or A -> C -> B), who can then broadcast it
or send it back to A.
N-1 of N
Generally the same as 2 of 3, except participants need to be arranged in a ring to pass their keys around
(using either the secure or insecure method).
For example (ignoring viewkey so letters line up):
[4 of 5]
User: spendkey
A: a
B: b
C: c
D: d
E: e
a -> B, b -> C, c -> D, d -> E, e -> A
Order of signing does not matter, it just must reach n-1 users. A "remaining keys" list must be passed around with
the transaction so the signers know if they should use 1 or both keys.
Collecting key image parts becomes a little messy, but basically every wallet sends over both of their parts with a tag for each.
Thia way the coordinating wallet can keep track of which images have been added and which wallet they come from. Reasoning:
1. The key images must be added only once (coordinator will get key images for key a from both A and B, he must add only one to get the proper key actual key image)
2. The coordinator must keep track of which helper pubkeys came from which wallet (discussed in 2 of 2 section). The coordinator
must choose only one set to use, then include his choice in the "remaining keys" list so the other wallets know which of their keys to use.
You can generalize it further to N-2 of N or even M of N, but I'm not sure there's legitimate demand to justify the complexity. It might
also be straightforward enough to support with minimal changes from N-1 format.
You basically just give each user additional keys for each additional "-1" you desire. N-2 would be 3 keys per user, N-3 4 keys, etc.
The process is somewhat cumbersome:
To create a N/N multisig wallet:
- each participant creates a normal wallet
- each participant runs "prepare_multisig", and sends the resulting string to every other participant
- each participant runs "make_multisig N A B C D...", with N being the threshold and A B C D... being the strings received from other participants (the threshold must currently equal N)
As txes are received, participants' wallets will need to synchronize so that those new outputs may be spent:
- each participant runs "export_multisig FILENAME", and sends the FILENAME file to every other participant
- each participant runs "import_multisig A B C D...", with A B C D... being the filenames received from other participants
Then, a transaction may be initiated:
- one of the participants runs "transfer ADDRESS AMOUNT"
- this partly signed transaction will be written to the "multisig_monero_tx" file
- the initiator sends this file to another participant
- that other participant runs "sign_multisig multisig_monero_tx"
- the resulting transaction is written to the "multisig_monero_tx" file again
- if the threshold was not reached, the file must be sent to another participant, until enough have signed
- the last participant to sign runs "submit_multisig multisig_monero_tx" to relay the transaction to the Monero network
7 years ago
if ( msout )
{
kLRki . push_back ( sources [ i ] . multisig_kLRki ) ;
}
}
for ( size_t i = 0 ; i < tx . vout . size ( ) ; + + i )
{
destinations . push_back ( rct : : pk2rct ( boost : : get < txout_to_key > ( tx . vout [ i ] . target ) . key ) ) ;
outamounts . push_back ( tx . vout [ i ] . amount ) ;
amount_out + = tx . vout [ i ] . amount ;
}
if ( use_simple_rct )
{
// mixRing indexing is done the other way round for simple
for ( size_t i = 0 ; i < sources . size ( ) ; + + i )
{
mixRing [ i ] . resize ( sources [ i ] . outputs . size ( ) ) ;
for ( size_t n = 0 ; n < sources [ i ] . outputs . size ( ) ; + + n )
{
mixRing [ i ] [ n ] = sources [ i ] . outputs [ n ] . second ;
}
}
}
else
{
for ( size_t i = 0 ; i < n_total_outs ; + + i ) // same index assumption
{
mixRing [ i ] . resize ( sources . size ( ) ) ;
for ( size_t n = 0 ; n < sources . size ( ) ; + + n )
{
mixRing [ i ] [ n ] = sources [ n ] . outputs [ i ] . second ;
}
}
}
// fee
if ( ! use_simple_rct & & amount_in > amount_out )
outamounts . push_back ( amount_in - amount_out ) ;
// zero out all amounts to mask rct outputs, real amounts are now encrypted
for ( size_t i = 0 ; i < tx . vin . size ( ) ; + + i )
{
if ( sources [ i ] . rct )
boost : : get < txin_to_key > ( tx . vin [ i ] ) . amount = 0 ;
}
for ( size_t i = 0 ; i < tx . vout . size ( ) ; + + i )
tx . vout [ i ] . amount = 0 ;
crypto : : hash tx_prefix_hash ;
get_transaction_prefix_hash ( tx , tx_prefix_hash , hwdev ) ;
rct : : ctkeyV outSk ;
if ( rct_config . range_proof_type ! = rct : : RangeProofPaddedBulletproof & & use_simple_rct )
tx . rct_signatures = rct : : genRctSimple_old ( rct : : hash2rct ( tx_prefix_hash ) , inSk , destinations , inamounts , outamounts , amount_in - amount_out , mixRing , amount_keys , msout ? & kLRki : NULL , msout , index , outSk , rct_config , hwdev ) ;
else if ( use_simple_rct & & rct_config . range_proof_type = = rct : : RangeProofPaddedBulletproof )
tx . rct_signatures = rct : : genRctSimple ( rct : : hash2rct ( tx_prefix_hash ) , inSk , destinations , inamounts , outamounts , amount_in - amount_out , mixRing , amount_keys , msout ? & kLRki : NULL , msout , index , outSk , rct_config , hwdev ) ;
else
tx . rct_signatures = rct : : genRct ( rct : : hash2rct ( tx_prefix_hash ) , inSk , destinations , outamounts , mixRing , amount_keys , msout ? & kLRki [ 0 ] : NULL , msout , sources [ 0 ] . real_output , outSk , rct_config , hwdev ) ; // same index assumption
memwipe ( inSk . data ( ) , inSk . size ( ) * sizeof ( rct : : ctkey ) ) ;
CHECK_AND_ASSERT_MES ( tx . vout . size ( ) = = outSk . size ( ) , false , " outSk size does not match vout " ) ;
MCINFO ( " construct_tx " , " transaction_created: " < < get_transaction_hash ( tx ) < < ENDL < < obj_to_json_str ( tx ) < < ENDL ) ;
}
tx . invalidate_hashes ( ) ;
return true ;
}
//---------------------------------------------------------------
bool construct_tx_and_get_tx_key ( const account_keys & sender_account_keys , const std : : unordered_map < crypto : : public_key , subaddress_index > & subaddresses , std : : vector < tx_source_entry > & sources , std : : vector < tx_destination_entry > & destinations , const boost : : optional < cryptonote : : account_public_address > & change_addr , const std : : vector < uint8_t > & extra , transaction & tx , uint64_t unlock_time , crypto : : secret_key & tx_key , std : : vector < crypto : : secret_key > & additional_tx_keys , bool rct , const rct : : RCTConfig & rct_config , rct : : multisig_out * msout )
Add N/N multisig tx generation and signing
Scheme by luigi1111:
Multisig for RingCT on Monero
2 of 2
User A (coordinator):
Spendkey b,B
Viewkey a,A (shared)
User B:
Spendkey c,C
Viewkey a,A (shared)
Public Address: C+B, A
Both have their own watch only wallet via C+B, a
A will coordinate spending process (though B could easily as well, coordinator is more needed for more participants)
A and B watch for incoming outputs
B creates "half" key images for discovered output D:
I2_D = (Hs(aR)+c) * Hp(D)
B also creates 1.5 random keypairs (one scalar and 2 pubkeys; one on base G and one on base Hp(D)) for each output, storing the scalar(k) (linked to D),
and sending the pubkeys with I2_D.
A also creates "half" key images:
I1_D = (Hs(aR)+b) * Hp(D)
Then I_D = I1_D + I2_D
Having I_D allows A to check spent status of course, but more importantly allows A to actually build a transaction prefix (and thus transaction).
A builds the transaction until most of the way through MLSAG_Gen, adding the 2 pubkeys (per input) provided with I2_D
to his own generated ones where they are needed (secret row L, R).
At this point, A has a mostly completed transaction (but with an invalid/incomplete signature). A sends over the tx and includes r,
which allows B (with the recipient's address) to verify the destination and amount (by reconstructing the stealth address and decoding ecdhInfo).
B then finishes the signature by computing ss[secret_index][0] = ss[secret_index][0] + k - cc[secret_index]*c (secret indices need to be passed as well).
B can then broadcast the tx, or send it back to A for broadcasting. Once B has completed the signing (and verified the tx to be valid), he can add the full I_D
to his cache, allowing him to verify spent status as well.
NOTE:
A and B *must* present key A and B to each other with a valid signature proving they know a and b respectively.
Otherwise, trickery like the following becomes possible:
A creates viewkey a,A, spendkey b,B, and sends a,A,B to B.
B creates a fake key C = zG - B. B sends C back to A.
The combined spendkey C+B then equals zG, allowing B to spend funds at any time!
The signature fixes this, because B does not know a c corresponding to C (and thus can't produce a signature).
2 of 3
User A (coordinator)
Shared viewkey a,A
"spendkey" j,J
User B
"spendkey" k,K
User C
"spendkey" m,M
A collects K and M from B and C
B collects J and M from A and C
C collects J and K from A and B
A computes N = nG, n = Hs(jK)
A computes O = oG, o = Hs(jM)
B anc C compute P = pG, p = Hs(kM) || Hs(mK)
B and C can also compute N and O respectively if they wish to be able to coordinate
Address: N+O+P, A
The rest follows as above. The coordinator possesses 2 of 3 needed keys; he can get the other
needed part of the signature/key images from either of the other two.
Alternatively, if secure communication exists between parties:
A gives j to B
B gives k to C
C gives m to A
Address: J+K+M, A
3 of 3
Identical to 2 of 2, except the coordinator must collect the key images from both of the others.
The transaction must also be passed an additional hop: A -> B -> C (or A -> C -> B), who can then broadcast it
or send it back to A.
N-1 of N
Generally the same as 2 of 3, except participants need to be arranged in a ring to pass their keys around
(using either the secure or insecure method).
For example (ignoring viewkey so letters line up):
[4 of 5]
User: spendkey
A: a
B: b
C: c
D: d
E: e
a -> B, b -> C, c -> D, d -> E, e -> A
Order of signing does not matter, it just must reach n-1 users. A "remaining keys" list must be passed around with
the transaction so the signers know if they should use 1 or both keys.
Collecting key image parts becomes a little messy, but basically every wallet sends over both of their parts with a tag for each.
Thia way the coordinating wallet can keep track of which images have been added and which wallet they come from. Reasoning:
1. The key images must be added only once (coordinator will get key images for key a from both A and B, he must add only one to get the proper key actual key image)
2. The coordinator must keep track of which helper pubkeys came from which wallet (discussed in 2 of 2 section). The coordinator
must choose only one set to use, then include his choice in the "remaining keys" list so the other wallets know which of their keys to use.
You can generalize it further to N-2 of N or even M of N, but I'm not sure there's legitimate demand to justify the complexity. It might
also be straightforward enough to support with minimal changes from N-1 format.
You basically just give each user additional keys for each additional "-1" you desire. N-2 would be 3 keys per user, N-3 4 keys, etc.
The process is somewhat cumbersome:
To create a N/N multisig wallet:
- each participant creates a normal wallet
- each participant runs "prepare_multisig", and sends the resulting string to every other participant
- each participant runs "make_multisig N A B C D...", with N being the threshold and A B C D... being the strings received from other participants (the threshold must currently equal N)
As txes are received, participants' wallets will need to synchronize so that those new outputs may be spent:
- each participant runs "export_multisig FILENAME", and sends the FILENAME file to every other participant
- each participant runs "import_multisig A B C D...", with A B C D... being the filenames received from other participants
Then, a transaction may be initiated:
- one of the participants runs "transfer ADDRESS AMOUNT"
- this partly signed transaction will be written to the "multisig_monero_tx" file
- the initiator sends this file to another participant
- that other participant runs "sign_multisig multisig_monero_tx"
- the resulting transaction is written to the "multisig_monero_tx" file again
- if the threshold was not reached, the file must be sent to another participant, until enough have signed
- the last participant to sign runs "submit_multisig multisig_monero_tx" to relay the transaction to the Monero network
7 years ago
{
hw : : device & hwdev = sender_account_keys . get_device ( ) ;
hwdev . open_tx ( tx_key ) ;
try {
// figure out if we need to make additional tx pubkeys
size_t num_stdaddresses = 0 ;
size_t num_subaddresses = 0 ;
account_public_address single_dest_subaddress ;
classify_addresses ( destinations , change_addr , num_stdaddresses , num_subaddresses , single_dest_subaddress ) ;
bool need_additional_txkeys = num_subaddresses > 0 & & ( num_stdaddresses > 0 | | num_subaddresses > 1 ) ;
if ( need_additional_txkeys )
{
additional_tx_keys . clear ( ) ;
for ( const auto & d : destinations )
additional_tx_keys . push_back ( keypair : : generate ( sender_account_keys . get_device ( ) ) . sec ) ;
}
Add N/N multisig tx generation and signing
Scheme by luigi1111:
Multisig for RingCT on Monero
2 of 2
User A (coordinator):
Spendkey b,B
Viewkey a,A (shared)
User B:
Spendkey c,C
Viewkey a,A (shared)
Public Address: C+B, A
Both have their own watch only wallet via C+B, a
A will coordinate spending process (though B could easily as well, coordinator is more needed for more participants)
A and B watch for incoming outputs
B creates "half" key images for discovered output D:
I2_D = (Hs(aR)+c) * Hp(D)
B also creates 1.5 random keypairs (one scalar and 2 pubkeys; one on base G and one on base Hp(D)) for each output, storing the scalar(k) (linked to D),
and sending the pubkeys with I2_D.
A also creates "half" key images:
I1_D = (Hs(aR)+b) * Hp(D)
Then I_D = I1_D + I2_D
Having I_D allows A to check spent status of course, but more importantly allows A to actually build a transaction prefix (and thus transaction).
A builds the transaction until most of the way through MLSAG_Gen, adding the 2 pubkeys (per input) provided with I2_D
to his own generated ones where they are needed (secret row L, R).
At this point, A has a mostly completed transaction (but with an invalid/incomplete signature). A sends over the tx and includes r,
which allows B (with the recipient's address) to verify the destination and amount (by reconstructing the stealth address and decoding ecdhInfo).
B then finishes the signature by computing ss[secret_index][0] = ss[secret_index][0] + k - cc[secret_index]*c (secret indices need to be passed as well).
B can then broadcast the tx, or send it back to A for broadcasting. Once B has completed the signing (and verified the tx to be valid), he can add the full I_D
to his cache, allowing him to verify spent status as well.
NOTE:
A and B *must* present key A and B to each other with a valid signature proving they know a and b respectively.
Otherwise, trickery like the following becomes possible:
A creates viewkey a,A, spendkey b,B, and sends a,A,B to B.
B creates a fake key C = zG - B. B sends C back to A.
The combined spendkey C+B then equals zG, allowing B to spend funds at any time!
The signature fixes this, because B does not know a c corresponding to C (and thus can't produce a signature).
2 of 3
User A (coordinator)
Shared viewkey a,A
"spendkey" j,J
User B
"spendkey" k,K
User C
"spendkey" m,M
A collects K and M from B and C
B collects J and M from A and C
C collects J and K from A and B
A computes N = nG, n = Hs(jK)
A computes O = oG, o = Hs(jM)
B anc C compute P = pG, p = Hs(kM) || Hs(mK)
B and C can also compute N and O respectively if they wish to be able to coordinate
Address: N+O+P, A
The rest follows as above. The coordinator possesses 2 of 3 needed keys; he can get the other
needed part of the signature/key images from either of the other two.
Alternatively, if secure communication exists between parties:
A gives j to B
B gives k to C
C gives m to A
Address: J+K+M, A
3 of 3
Identical to 2 of 2, except the coordinator must collect the key images from both of the others.
The transaction must also be passed an additional hop: A -> B -> C (or A -> C -> B), who can then broadcast it
or send it back to A.
N-1 of N
Generally the same as 2 of 3, except participants need to be arranged in a ring to pass their keys around
(using either the secure or insecure method).
For example (ignoring viewkey so letters line up):
[4 of 5]
User: spendkey
A: a
B: b
C: c
D: d
E: e
a -> B, b -> C, c -> D, d -> E, e -> A
Order of signing does not matter, it just must reach n-1 users. A "remaining keys" list must be passed around with
the transaction so the signers know if they should use 1 or both keys.
Collecting key image parts becomes a little messy, but basically every wallet sends over both of their parts with a tag for each.
Thia way the coordinating wallet can keep track of which images have been added and which wallet they come from. Reasoning:
1. The key images must be added only once (coordinator will get key images for key a from both A and B, he must add only one to get the proper key actual key image)
2. The coordinator must keep track of which helper pubkeys came from which wallet (discussed in 2 of 2 section). The coordinator
must choose only one set to use, then include his choice in the "remaining keys" list so the other wallets know which of their keys to use.
You can generalize it further to N-2 of N or even M of N, but I'm not sure there's legitimate demand to justify the complexity. It might
also be straightforward enough to support with minimal changes from N-1 format.
You basically just give each user additional keys for each additional "-1" you desire. N-2 would be 3 keys per user, N-3 4 keys, etc.
The process is somewhat cumbersome:
To create a N/N multisig wallet:
- each participant creates a normal wallet
- each participant runs "prepare_multisig", and sends the resulting string to every other participant
- each participant runs "make_multisig N A B C D...", with N being the threshold and A B C D... being the strings received from other participants (the threshold must currently equal N)
As txes are received, participants' wallets will need to synchronize so that those new outputs may be spent:
- each participant runs "export_multisig FILENAME", and sends the FILENAME file to every other participant
- each participant runs "import_multisig A B C D...", with A B C D... being the filenames received from other participants
Then, a transaction may be initiated:
- one of the participants runs "transfer ADDRESS AMOUNT"
- this partly signed transaction will be written to the "multisig_monero_tx" file
- the initiator sends this file to another participant
- that other participant runs "sign_multisig multisig_monero_tx"
- the resulting transaction is written to the "multisig_monero_tx" file again
- if the threshold was not reached, the file must be sent to another participant, until enough have signed
- the last participant to sign runs "submit_multisig multisig_monero_tx" to relay the transaction to the Monero network
7 years ago
bool r = construct_tx_with_tx_key ( sender_account_keys , subaddresses , sources , destinations , change_addr , extra , tx , unlock_time , tx_key , additional_tx_keys , rct , rct_config , msout ) ;
hwdev . close_tx ( ) ;
return r ;
} catch ( . . . ) {
hwdev . close_tx ( ) ;
throw ;
Add N/N multisig tx generation and signing
Scheme by luigi1111:
Multisig for RingCT on Monero
2 of 2
User A (coordinator):
Spendkey b,B
Viewkey a,A (shared)
User B:
Spendkey c,C
Viewkey a,A (shared)
Public Address: C+B, A
Both have their own watch only wallet via C+B, a
A will coordinate spending process (though B could easily as well, coordinator is more needed for more participants)
A and B watch for incoming outputs
B creates "half" key images for discovered output D:
I2_D = (Hs(aR)+c) * Hp(D)
B also creates 1.5 random keypairs (one scalar and 2 pubkeys; one on base G and one on base Hp(D)) for each output, storing the scalar(k) (linked to D),
and sending the pubkeys with I2_D.
A also creates "half" key images:
I1_D = (Hs(aR)+b) * Hp(D)
Then I_D = I1_D + I2_D
Having I_D allows A to check spent status of course, but more importantly allows A to actually build a transaction prefix (and thus transaction).
A builds the transaction until most of the way through MLSAG_Gen, adding the 2 pubkeys (per input) provided with I2_D
to his own generated ones where they are needed (secret row L, R).
At this point, A has a mostly completed transaction (but with an invalid/incomplete signature). A sends over the tx and includes r,
which allows B (with the recipient's address) to verify the destination and amount (by reconstructing the stealth address and decoding ecdhInfo).
B then finishes the signature by computing ss[secret_index][0] = ss[secret_index][0] + k - cc[secret_index]*c (secret indices need to be passed as well).
B can then broadcast the tx, or send it back to A for broadcasting. Once B has completed the signing (and verified the tx to be valid), he can add the full I_D
to his cache, allowing him to verify spent status as well.
NOTE:
A and B *must* present key A and B to each other with a valid signature proving they know a and b respectively.
Otherwise, trickery like the following becomes possible:
A creates viewkey a,A, spendkey b,B, and sends a,A,B to B.
B creates a fake key C = zG - B. B sends C back to A.
The combined spendkey C+B then equals zG, allowing B to spend funds at any time!
The signature fixes this, because B does not know a c corresponding to C (and thus can't produce a signature).
2 of 3
User A (coordinator)
Shared viewkey a,A
"spendkey" j,J
User B
"spendkey" k,K
User C
"spendkey" m,M
A collects K and M from B and C
B collects J and M from A and C
C collects J and K from A and B
A computes N = nG, n = Hs(jK)
A computes O = oG, o = Hs(jM)
B anc C compute P = pG, p = Hs(kM) || Hs(mK)
B and C can also compute N and O respectively if they wish to be able to coordinate
Address: N+O+P, A
The rest follows as above. The coordinator possesses 2 of 3 needed keys; he can get the other
needed part of the signature/key images from either of the other two.
Alternatively, if secure communication exists between parties:
A gives j to B
B gives k to C
C gives m to A
Address: J+K+M, A
3 of 3
Identical to 2 of 2, except the coordinator must collect the key images from both of the others.
The transaction must also be passed an additional hop: A -> B -> C (or A -> C -> B), who can then broadcast it
or send it back to A.
N-1 of N
Generally the same as 2 of 3, except participants need to be arranged in a ring to pass their keys around
(using either the secure or insecure method).
For example (ignoring viewkey so letters line up):
[4 of 5]
User: spendkey
A: a
B: b
C: c
D: d
E: e
a -> B, b -> C, c -> D, d -> E, e -> A
Order of signing does not matter, it just must reach n-1 users. A "remaining keys" list must be passed around with
the transaction so the signers know if they should use 1 or both keys.
Collecting key image parts becomes a little messy, but basically every wallet sends over both of their parts with a tag for each.
Thia way the coordinating wallet can keep track of which images have been added and which wallet they come from. Reasoning:
1. The key images must be added only once (coordinator will get key images for key a from both A and B, he must add only one to get the proper key actual key image)
2. The coordinator must keep track of which helper pubkeys came from which wallet (discussed in 2 of 2 section). The coordinator
must choose only one set to use, then include his choice in the "remaining keys" list so the other wallets know which of their keys to use.
You can generalize it further to N-2 of N or even M of N, but I'm not sure there's legitimate demand to justify the complexity. It might
also be straightforward enough to support with minimal changes from N-1 format.
You basically just give each user additional keys for each additional "-1" you desire. N-2 would be 3 keys per user, N-3 4 keys, etc.
The process is somewhat cumbersome:
To create a N/N multisig wallet:
- each participant creates a normal wallet
- each participant runs "prepare_multisig", and sends the resulting string to every other participant
- each participant runs "make_multisig N A B C D...", with N being the threshold and A B C D... being the strings received from other participants (the threshold must currently equal N)
As txes are received, participants' wallets will need to synchronize so that those new outputs may be spent:
- each participant runs "export_multisig FILENAME", and sends the FILENAME file to every other participant
- each participant runs "import_multisig A B C D...", with A B C D... being the filenames received from other participants
Then, a transaction may be initiated:
- one of the participants runs "transfer ADDRESS AMOUNT"
- this partly signed transaction will be written to the "multisig_monero_tx" file
- the initiator sends this file to another participant
- that other participant runs "sign_multisig multisig_monero_tx"
- the resulting transaction is written to the "multisig_monero_tx" file again
- if the threshold was not reached, the file must be sent to another participant, until enough have signed
- the last participant to sign runs "submit_multisig multisig_monero_tx" to relay the transaction to the Monero network
7 years ago
}
}
//---------------------------------------------------------------
bool construct_tx ( const account_keys & sender_account_keys , std : : vector < tx_source_entry > & sources , const std : : vector < tx_destination_entry > & destinations , const boost : : optional < cryptonote : : account_public_address > & change_addr , const std : : vector < uint8_t > & extra , transaction & tx , uint64_t unlock_time )
{
std : : unordered_map < crypto : : public_key , cryptonote : : subaddress_index > subaddresses ;
subaddresses [ sender_account_keys . m_account_address . m_spend_public_key ] = { 0 , 0 } ;
crypto : : secret_key tx_key ;
std : : vector < crypto : : secret_key > additional_tx_keys ;
std : : vector < tx_destination_entry > destinations_copy = destinations ;
return construct_tx_and_get_tx_key ( sender_account_keys , subaddresses , sources , destinations_copy , change_addr , extra , tx , unlock_time , tx_key , additional_tx_keys , false , { rct : : RangeProofBorromean , 0 } , NULL ) ;
}
//---------------------------------------------------------------
bool generate_genesis_block (
block & bl
, std : : string const & genesis_tx
, uint32_t nonce
)
{
//genesis block
bl = { } ;
blobdata tx_bl ;
bool r = string_tools : : parse_hexstr_to_binbuff ( genesis_tx , tx_bl ) ;
CHECK_AND_ASSERT_MES ( r , false , " failed to parse coinbase tx from hard coded blob " ) ;
r = parse_and_validate_tx_from_blob ( tx_bl , bl . miner_tx ) ;
CHECK_AND_ASSERT_MES ( r , false , " failed to parse coinbase tx from hard coded blob " ) ;
bl . major_version = CURRENT_BLOCK_MAJOR_VERSION ;
bl . minor_version = CURRENT_BLOCK_MINOR_VERSION ;
bl . timestamp = 0 ;
bl . nonce = nonce ;
miner : : find_nonce_for_given_block ( [ ] ( const cryptonote : : block & b , uint64_t height , unsigned int threads , crypto : : hash & hash ) {
return cryptonote : : get_block_longhash ( NULL , b , hash , height , threads ) ;
} , bl , 1 , 0 ) ;
bl . invalidate_hashes ( ) ;
return true ;
}
//---------------------------------------------------------------
void get_altblock_longhash ( const block & b , crypto : : hash & res , const uint64_t main_height , const uint64_t height , const uint64_t seed_height , const crypto : : hash & seed_hash )
{
blobdata bd = get_block_hashing_blob ( b ) ;
rx_slow_hash ( main_height , seed_height , seed_hash . data , bd . data ( ) , bd . size ( ) , res . data , 0 , 1 ) ;
}
bool get_block_longhash ( const Blockchain * pbc , const block & b , crypto : : hash & res , const uint64_t height , const int miners )
{
blobdata bd = get_block_hashing_blob ( b ) ;
if ( b . major_version > = RX_BLOCK_VERSION )
{
uint64_t seed_height , main_height ;
crypto : : hash hash ;
if ( pbc ! = NULL )
{
seed_height = rx_seedheight ( height ) ;
hash = pbc - > get_pending_block_id_by_height ( seed_height ) ;
main_height = pbc - > get_current_blockchain_height ( ) ;
} else
{
memset ( & hash , 0 , sizeof ( hash ) ) ; // only happens when generating genesis block
seed_height = 0 ;
main_height = 0 ;
}
rx_slow_hash ( main_height , seed_height , hash . data , bd . data ( ) , bd . size ( ) , res . data , miners , 0 ) ;
} else {
const int pow_variant = b . major_version > = 11 ? 4 : b . major_version > = 9 ? 2 : 1 ;
crypto : : cn_slow_hash ( bd . data ( ) , bd . size ( ) , res , pow_variant , height ) ;
}
return true ;
}
crypto : : hash get_block_longhash ( const Blockchain * pbc , const block & b , const uint64_t height , const int miners )
{
crypto : : hash p = crypto : : null_hash ;
get_block_longhash ( pbc , b , p , height , miners ) ;
return p ;
}
void get_block_longhash_reorg ( const uint64_t split_height )
{
rx_reorg ( split_height ) ;
}
}
