Examples from ECDSA and DER Signatures

All examples from the ECDSA and DER signatures documentation chapter are shown here in full. The specific examples referenced in the subsections are wrapped in the functions listed below.

ECDSA, DER signatures

• ecdsa_der_signing();

Libbitcoin API: Version 3.

Script below is ready-to-compile: g++ -std=c++11 -o ecdsa_der ecdsa_der_examples.cpp $(pkg-config --cflags libbitcoin --libs libbitcoin)

#include <bitcoin/bitcoin.hpp>
#include <string.h>
#include <iostream>

using namespace bc;

void ecdsa_der_signing()
{
    //********** Part 1 **********

    // Hash of an arbitrary message.
    auto message = base16_literal(
  	 "04c294ab836b61955e762547c561a45e4be88984dca06da959d47bf880fd92f4");
    auto my_hash = bitcoin_hash(message);

    // My private & public keys.
    auto my_secret = base16_literal(
        "f3c8f9a6198cca98f481edde13bcc031b1470a81e367b838fe9e0a9db0f5993d");
    ec_compressed my_pubkey;
    secret_to_public(my_pubkey, my_secret);

    // Sign hash of TX with my private key.
    ec_signature my_signature;
    sign(my_signature, my_secret, my_hash);

    // Verify Signature.
    std::cout << verify_signature(my_pubkey, my_hash, my_signature)
              << std::endl;

    //********** Part 2 **********

    // Format signature (r,s) as DER.
    der_signature my_der_signature;
    encode_signature(my_der_signature, my_signature);

    // DER serialisation.
    std::cout << encode_base16(my_der_signature)
              << std::endl;

    //********** Part 3 **********

    // Parse r,s values from DER formatted signature.
    // Strict enforcement of DER = true.
    std::cout << parse_signature(my_signature, my_der_signature, true)
              << std::endl;
}

int main()
{
  ecdsa_der_signing();
  return 0;
}