add sending to subaddresses support

cryptonote_utils/cryptonote_utils.js

@@ -54,6 +54,7 @@ var cnUtil = function(currencyConfig)
 	var ENCRYPTED_PAYMENT_ID_TAIL = 141;
 	var CRYPTONOTE_PUBLIC_ADDRESS_BASE58_PREFIX = config.addressPrefix;
 	var CRYPTONOTE_PUBLIC_INTEGRATED_ADDRESS_BASE58_PREFIX = config.integratedAddressPrefix;
+	var CRYPTONOTE_PUBLIC_INTEGRATED_SUBADDRESS_BASE58_PREFIX = 42;
 	var UINT64_MAX = new JSBigInt(2).pow(64);
 	var CURRENT_TX_VERSION = 2;
 	var OLD_TX_VERSION = 1;
@@ -489,8 +490,9 @@ var cnUtil = function(currencyConfig)
 		var dec = cnBase58.decode(address);
 		var expectedPrefix = this.encode_varint(CRYPTONOTE_PUBLIC_ADDRESS_BASE58_PREFIX);
 		var expectedPrefixInt = this.encode_varint(CRYPTONOTE_PUBLIC_INTEGRATED_ADDRESS_BASE58_PREFIX);
+		var expectedPrefixSub = this.encode_varint(CRYPTONOTE_PUBLIC_SUBADDRESS_BASE58_PREFIX);
 		var prefix = dec.slice(0, expectedPrefix.length);
-		if (prefix !== expectedPrefix && prefix !== expectedPrefixInt) {
+		if (prefix !== expectedPrefix && prefix !== expectedPrefixInt && prefix !== expectedPrefixSub) {
 			throw "Invalid address prefix";
 		}
 		dec = dec.slice(expectedPrefix.length);
@@ -520,6 +522,14 @@ var cnUtil = function(currencyConfig)
 			};
 		}
 	};
+	
+	this.is_subaddress = function(addr) {
+		var decoded = cnBase58.decode(addr);
+		var subaddressPrefix = this.encode_varint(CRYPTONOTE_PUBLIC_SUBADDRESS_BASE58_PREFIX);
+        	var prefix = decoded.slice(0, subaddressPrefix.length);
+        
+        	return (prefix === subaddressPrefix);
+	};
 
 	this.valid_keys = function(view_pub, view_sec, spend_pub, spend_sec) {
 		var expected_view_pub = this.sec_key_to_pub(view_sec);
@@ -1623,7 +1633,6 @@ var cnUtil = function(currencyConfig)
 		} else {
 			tx.signatures = [];
 		}
-		tx.extra = this.add_pub_key_to_extra(tx.extra, txkey.pub);
 
 		var in_contexts = [];
 		var inputs_money = JSBigInt.ZERO;
@@ -1670,7 +1679,23 @@ var cnUtil = function(currencyConfig)
 				throw "dst.amount < 0"; //amount can be zero if no change
 			}
 			dsts[i].keys = this.decode_address(dsts[i].address);
-			var out_derivation = this.generate_key_derivation(dsts[i].keys.view, txkey.sec);
+			
+			// R = rD for subaddresses
+			if(this.is_subaddress(dsts[i].address)) {
+				txkey.pub = ge_scalarmult(dsts[i].keys.spend, txkey.sec);
+			}
+			
+			var out_derivation;
+			
+			// send change to ourselves
+			if(dsts[i].keys.view == keys.view.pub) {
+				out_derivation = this.generate_key_derivation(txkey.pub, keys.view.sec);
+			}
+			
+			else {
+				out_derivation = this.generate_key_derivation(dsts[i].keys.view, txkey.sec);
+			}
+			
 			if (rct) {
 				amountKeys.push(this.derivation_to_scalar(out_derivation, out_index));
 			}
@@ -1687,6 +1712,10 @@ var cnUtil = function(currencyConfig)
 			++out_index;
 			outputs_money = outputs_money.add(dsts[i].amount);
 		}
+		
+		// add pub key to extra after we know whether to use R = rG or R = rD
+		tx.extra = this.add_pub_key_to_extra(tx.extra, txkey.pub);
+		
 		if (outputs_money.add(fee_amount).compare(inputs_money) > 0) {
 			throw "outputs money (" + this.formatMoneyFull(outputs_money) + ") + fee (" + this.formatMoneyFull(fee_amount) + ") > inputs money (" + this.formatMoneyFull(inputs_money) + ")";
 		}
@@ -2067,4 +2096,4 @@ var cnUtil = function(currencyConfig)
 
 	return this;
 }
-exports.cnUtil = cnUtil
+exports.cnUtil = cnUtil