Bitcoin Forum

bool test_key_generation(FILE* out)
{
	//First notice
	fprintf(out, "\n--- Test public key generation ---\n");

	//Setting up domain parameters
	domain_parameters curve = domain_parameters_init();
	domain_parameters_load_curve(curve, secp160r1);

	//Public key
	point Q = point_init();
	point Q_check = point_init();

	//Private key
	mpz_t d;mpz_init(d);

	//Load key from GEC test vectors
	mpz_set_str(d, "971761939728640320549601132085879836204587084162", 10);

	//Load correct result from GEC test vectors
	point_set_str(Q_check, "466448783855397898016055842232266600516272889280", "1110706324081757720403272427311003102474457754220", 10);

	//Generate public key
	signature_generate_key(Q, d, curve);

#include <QCoreApplication>
#include <QByteArray>

#include <stdio.h>

#include <openssl/ec.h>
#include <openssl/evp.h>
#include <openssl/ecdsa.h>
#include <openssl/bn.h>

static EC_KEY* EC_KEY_regenerate_key ( const quint8* priv )
{
  static EC_KEY* eckey = EC_KEY_new_by_curve_name ( NID_secp256k1 );
  static const EC_GROUP* group = EC_KEY_get0_group ( eckey );
  BIGNUM* privkey = BN_bin2bn ( priv, 32, BN_new ( ) );
  BN_CTX* ctx = BN_CTX_new ( );
  EC_POINT* pubkey = EC_POINT_new ( group );
  EC_POINT_mul ( group, pubkey, privkey, 0, 0, ctx );
  EC_KEY_set_private_key ( eckey, privkey );
  EC_KEY_set_public_key ( eckey, pubkey );
  EC_POINT_free ( pubkey );
  BN_CTX_free ( ctx );
  BN_clear_free ( privkey );
  return eckey;
}
//--------------------------------------------------------------
static const char* getPublicKey ( char* buf, const quint8* priv )
{
  quint8 pubkey [65];
  quint8* pbegin = pubkey;
  i2o_ECPublicKey ( EC_KEY_regenerate_key ( priv ), &pbegin );
  memcpy ( buf, pubkey + 1, 64 ); // without 0x04 prefix
  return (const char*)buf;
}
//--------------------------------------------------------------
static const QByteArray getPublicKeyClassic ( const quint8* priv )
{
  char buf [65];
  getPublicKey ( buf + 1, priv );
  buf [0] = 0x04;
  return QByteArray ( buf, 65 );
}
//--------------------------------------------------------------
static const QByteArray getPublicKeyCompressed ( const quint8* priv )
{
  char buf [65];
  getPublicKey ( buf + 1, priv );
  buf [0] = 0x02 + ( buf [64] & 1 );
  return QByteArray ( buf, 33 );
}
//--------------------------------------------------------------
int main ( int argc, char* argv [] )
{
  QCoreApplication a ( argc, argv );
  // correct horse battery staple
  const QByteArray priv ( QByteArray::fromHex ( "c4bbcb1fbec99d65bf59d85c8cb62ee2db963f0fe106f483d9afa73bd4e39a8a" ) );
  printf ( "classic=%s\n", getPublicKeyClassic ( (const quint8*)priv.constData ( ) ).toHex ( ).constData ( ) );
  printf ( "compressed=%s\n", getPublicKeyCompressed ( (const quint8*)priv.constData ( ) ).toHex ( ).constData ( ) );
  return a.exec ( );
}

classic=0478d430274f8c5ec1321338151e9f27f4c676a008bdf8638d07c0b6be9ab35c71a1518063243acd4dfe96b66e3f2ec8013c8e072cd09b3834a19f81f659cc3455
compressed=0378d430274f8c5ec1321338151e9f27f4c676a008bdf8638d07c0b6be9ab35c71

inv1, inv2 = inv2, inv1 - inv2 * (x / p)
x, p = p, x % p

temp = inv2
inv2 = inv1 - inv2 * (x / p)
inv1 = temp

temp = p
p = x % p
x = temp