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recover public key from ecdsa,v sig using cryptopp

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subtly 2014-10-29 18:46:57 +01:00
parent 3c98874b97
commit 7f7a800fa1
1 changed files with 108 additions and 0 deletions
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108
crypto.cpp
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@ -86,6 +86,114 @@ BOOST_AUTO_TEST_CASE(cryptopp_vs_secp256k1)
}
}
BOOST_AUTO_TEST_CASE(cryptopp_cryptopp_ecdsav)
{
// cryptopp implementation of secp256k1lib sign_compact w/recid parameter for recovering public key from signature
// cryptopp does this:
// void Sign(const DL_GroupParameters<T> &params, const Integer &x, const Integer &k, const Integer &e, Integer &r, Integer &s) const
// {
// const Integer &q = params.GetSubgroupOrder();
// r %= q;
// Integer kInv = k.InverseMod(q);
// s = (kInv * (x*r + e)) % q;
// assert(!!r && !!s);
// }
// secp256k1lib does this, which we want cryptopp to do:
// secp256k1_gej_t rp;
// secp256k1_ecmult_gen(&rp, nonce);
// secp256k1_ge_t r;
// secp256k1_ge_set_gej(&r, &rp);
// unsigned char b[32];
// secp256k1_fe_normalize(&r.x);
// secp256k1_fe_normalize(&r.y);
// secp256k1_fe_get_b32(b, &r.x);
// secp256k1_num_set_bin(&sig->r, b, 32);
// if (recid)
// *recid = (secp256k1_num_cmp(&sig->r, &c->order) >= 0 ? 2 : 0) | (secp256k1_fe_is_odd(&r.y) ? 1 : 0);
// secp256k1_num_mod(&sig->r, &c->order);
// secp256k1_num_t n;
// secp256k1_num_init(&n);
// secp256k1_num_mod_mul(&n, &sig->r, seckey, &c->order);
// secp256k1_num_add(&n, &n, message);
// secp256k1_num_mod(&n, &c->order);
// secp256k1_num_mod_inverse(&sig->s, nonce, &c->order);
// secp256k1_num_mod_mul(&sig->s, &sig->s, &n, &c->order);
// secp256k1_num_free(&n);
// if (secp256k1_num_is_zero(&sig->s))
// return 0;
// if (secp256k1_num_cmp(&sig->s, &c->half_order) > 0) {
// secp256k1_num_sub(&sig->s, &c->order, &sig->s);
// if (recid)
// *recid ^= 1;
// }
// secret
Secret secret(sha3("privacy"));
// e := sha3(msg)
bytes e(fromHex("0x01"));
e.resize(32);
int tests = 150; // Oct 29: successful @ 1500
while (sha3(&e, &e), secret = sha3(secret.asBytes()), tests--)
{
KeyPair key(secret);
h256 he(sha3(e));
Integer heInt(he.asBytes().data(), 32);
h256 k(he ^ key.sec());
Integer kInt(k.asBytes().data(), 32);
// we get ec params from signer
ECDSA<ECP, SHA3_256>::Signer signer;
pp::initializeSigner(key.sec(), signer);
const DL_GroupParameters<ECP::Point> &params = signer.GetKey().GetAbstractGroupParameters();
ECP::Point rp = params.ExponentiateBase(kInt);
Integer const& q = params.GetGroupOrder();
Integer r = params.ConvertElementToInteger(rp);
int recid = ((r >= q) ? 2 : 0) | (rp.y.IsOdd() ? 1 : 0);
BOOST_REQUIRE(!(r>=q)); // interesting, this never happens
r %= q;
Integer kInv = kInt.InverseMod(q);
Integer s = (kInv * (Integer(key.sec().asBytes().data(), 32)*r + heInt)) % q;
BOOST_REQUIRE(!!r && !!s);
if (s > params.GetSubgroupOrder())
{
// also interesting, this never happens
s = params.GetGroupOrder() - s;
if (recid)
recid ^= 1;
}
BOOST_REQUIRE(recid < 2);
Signature sig;
r.Encode(sig.data(), 32);
s.Encode(sig.data()+32, 32);
sig[64] = recid;
Public p = dev::recover(sig, he);
Public pkey = key.pub();
BOOST_REQUIRE(p == pkey);
// verify w/cryptopp
BOOST_REQUIRE(crypto::verify(key.pub(), sig, bytesConstRef(&e)));
// verify with secp256k1lib
byte encpub[65] = {0x04};
memcpy(&encpub[1], key.pub().data(), 64);
byte dersig[72];
size_t cssz = DSAConvertSignatureFormat(dersig, 72, DSA_DER, sig.data(), 64, DSA_P1363);
BOOST_CHECK(cssz <= 72);
BOOST_REQUIRE(1 == secp256k1_ecdsa_verify(he.data(), sizeof(he), dersig, cssz, encpub, 65));
}
}
BOOST_AUTO_TEST_CASE(cryptopp_ecdsa_sipaseckp256k1)
{
// cryptopp integer encoding