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/*
* GOST 34.10-2001 implemenation
* (C) 2007 Falko Strenzke, FlexSecure GmbH
* Manuel Hartl, FlexSecure GmbH
* (C) 2008-2010 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#include <botan/gost_3410.h>
#include <botan/der_enc.h>
#include <botan/ber_dec.h>
namespace Botan {
MemoryVector<byte> GOST_3410_PublicKey::x509_subject_public_key() const
{
// Trust CryptoPro to come up with something obnoxious
const BigInt& x = public_point().get_affine_x();
const BigInt& y = public_point().get_affine_y();
MemoryVector<byte> bits(2*std::max(x.bytes(), y.bytes()));
y.binary_encode(bits + (bits.size() / 2 - y.bytes()));
x.binary_encode(bits + (bits.size() - x.bytes()));
return DER_Encoder().encode(bits, OCTET_STRING).get_contents();
}
AlgorithmIdentifier GOST_3410_PublicKey::algorithm_identifier() const
{
MemoryVector<byte> params =
DER_Encoder().start_cons(SEQUENCE)
.encode(OID(domain().get_oid()))
.end_cons()
.get_contents();
return AlgorithmIdentifier(get_oid(), params);
}
GOST_3410_PublicKey::GOST_3410_PublicKey(const AlgorithmIdentifier& alg_id,
const MemoryRegion<byte>& key_bits)
{
OID ecc_param_id;
// Also includes hash and cipher OIDs... brilliant design guys
BER_Decoder(alg_id.parameters).start_cons(SEQUENCE).decode(ecc_param_id);
domain_params = EC_Domain_Params(ecc_param_id);
SecureVector<byte> bits;
BER_Decoder(key_bits).decode(bits, OCTET_STRING);
const u32bit part_size = bits.size() / 2;
BigInt y(bits, part_size);
BigInt x(bits + part_size, part_size);
public_key = PointGFp(domain().get_curve(), x, y);
try
{
public_key.check_invariants();
}
catch(Illegal_Point)
{
throw Internal_Error("Loaded ECC public key failed self test");
}
}
bool GOST_3410_PublicKey::verify(const byte msg[], u32bit msg_len,
const byte sig[], u32bit sig_len) const
{
const BigInt& n = domain().get_order();
if(n == 0)
throw Invalid_State("domain parameters not set");
if(sig_len != n.bytes()*2)
return false;
BigInt e(msg, msg_len);
BigInt r(sig, sig_len / 2);
BigInt s(sig + sig_len / 2, sig_len / 2);
if(r < 0 || r >= n || s < 0 || s >= n)
return false;
e %= n;
if(e == 0)
e = 1;
BigInt v = inverse_mod(e, n);
BigInt z1 = (s*v) % n;
BigInt z2 = (-r*v) % n;
PointGFp R = (z1 * domain().get_base_point() + z2 * public_point());
return (R.get_affine_x() == r);
}
SecureVector<byte>
GOST_3410_PrivateKey::sign(const byte msg[],
u32bit msg_len,
RandomNumberGenerator& rng) const
{
if(private_value() == 0)
throw Invalid_State("GOST_3410::sign(): no private key");
const BigInt& n = domain().get_order();
if(n == 0)
throw Invalid_State("GOST_3410::sign(): domain parameters not set");
BigInt k;
do
k.randomize(rng, n.bits()-1);
while(k >= n);
BigInt e(msg, msg_len);
e %= n;
if(e == 0)
e = 1;
PointGFp k_times_P = domain().get_base_point() * k;
k_times_P.check_invariants();
BigInt r = k_times_P.get_affine_x() % n;
if(r == 0)
throw Invalid_State("GOST_3410::sign: r was zero");
BigInt s = (r*private_value() + k*e) % n;
SecureVector<byte> output(2*n.bytes());
r.binary_encode(output + (output.size() / 2 - r.bytes()));
s.binary_encode(output + (output.size() - s.bytes()));
return output;
}
GOST_3410_Signature_Operation::GOST_3410_Signature_Operation(
const GOST_3410_PrivateKey& gost_3410) :
base_point(gost_3410.domain().get_base_point()),
order(gost_3410.domain().get_order()),
x(gost_3410.private_value())
{
}
SecureVector<byte> GOST_3410_Signature_Operation::sign(const byte msg[],
u32bit msg_len,
RandomNumberGenerator& rng)
{
BigInt k;
do
k.randomize(rng, order.bits()-1);
while(k >= order);
BigInt e(msg, msg_len);
e %= order;
if(e == 0)
e = 1;
PointGFp k_times_P = base_point * k;
k_times_P.check_invariants();
BigInt r = k_times_P.get_affine_x() % order;
BigInt s = (r*x + k*e) % order;
if(r == 0 || s == 0)
throw Invalid_State("GOST 34.10: r == 0 || s == 0");
SecureVector<byte> output(2*order.bytes());
r.binary_encode(output + (output.size() / 2 - r.bytes()));
s.binary_encode(output + (output.size() - s.bytes()));
return output;
}
}
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