diff --git a/src/monero_paymentID_utils.cpp b/src/monero_paymentID_utils.cpp
index fa3d47d..7e717ba 100644
--- a/src/monero_paymentID_utils.cpp
+++ b/src/monero_paymentID_utils.cpp
@@ -29,13 +29,14 @@
 //  THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 //
 //
-
 #include "monero_paymentID_utils.hpp"
+#import <regex>
 #include "cryptonote_basic.h"
 #include "cryptonote_basic/blobdatatype.h"
-//
 #include "string_tools.h"
 using namespace epee;
+using namespace std;
+using namespace boost;
 //
 //
 crypto::hash8 monero_paymentID_utils::new_short_plain_paymentID()
@@ -86,3 +87,27 @@ bool monero_paymentID_utils::parse_payment_id(const std::string& payment_id_str,
 	}
 	return false;
 }
+//
+bool monero_paymentID_utils::is_a_valid_or_not_a_payment_id_of_length(const string &str, size_t length)
+{
+	if (str.size() != length) {
+		return false;
+	}
+	stringstream ss;
+	ss << "^[0-9a-fA-F]{" << length << "}$";
+	if (regex_match(str, regex(ss.str()))) {
+		return true;
+	}
+	return false;
+}
+bool monero_paymentID_utils::is_a_valid_or_not_a_payment_id(optional<string> str)
+{
+	if (str == boost::none || str->empty()) {
+		return true; // not a payment id b/c it's nil
+	}
+	if (is_a_valid_or_not_a_payment_id_of_length(*str, payment_id_length__short)
+		|| is_a_valid_or_not_a_payment_id_of_length(*str, payment_id_length__long)) {
+		return true;
+	}
+	return false; // not a match but not empty/nil either
+}
diff --git a/src/monero_paymentID_utils.hpp b/src/monero_paymentID_utils.hpp
index 9a746f9..d9de46b 100644
--- a/src/monero_paymentID_utils.hpp
+++ b/src/monero_paymentID_utils.hpp
@@ -34,19 +34,30 @@
 #define monero_paymentID_utils_hpp
 
 #include <stdio.h>
+#include <boost/optional.hpp>
 #include "crypto.h"
 
 namespace monero_paymentID_utils
 {
+	using namespace std;
+	using namespace boost;
+	//
+	// Constants
+	static const size_t payment_id_length__short = 16;
+	static const size_t payment_id_length__long = 64;
 	//
 	// Generating Payment IDs
 	crypto::hash8 new_short_plain_paymentID();
-	std::string new_short_plain_paymentID_string();
+	string new_short_plain_paymentID_string();
 	//
 	// Parsing and Detecting Payment IDs
-	bool parse_long_payment_id(const std::string& payment_id_str, crypto::hash& payment_id);
-	bool parse_short_payment_id(const std::string& payment_id_str, crypto::hash8& payment_id);
-	bool parse_payment_id(const std::string& payment_id_str, crypto::hash& payment_id);
+	bool parse_long_payment_id(const string& payment_id_str, crypto::hash& payment_id);
+	bool parse_short_payment_id(const string& payment_id_str, crypto::hash8& payment_id);
+	bool parse_payment_id(const string& payment_id_str, crypto::hash& payment_id);
+	//
+	// Validating payment IDs
+	bool is_a_valid_or_not_a_payment_id_of_length(const string &str, size_t length);
+	bool is_a_valid_or_not_a_payment_id(optional<string> str); // this checks 16 and then 64 len strs
 }
 
 #endif /* monero_paymentID_utils_hpp */