I2P: End-to-End encrypted and anonymous Internet https://i2pd.website/
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#include <array>
#include <openssl/evp.h>
#include "Gost.h"
namespace i2p
{
namespace crypto
{
GOSTR3410Curve::GOSTR3410Curve (BIGNUM * a, BIGNUM * b, BIGNUM * p, BIGNUM * q, BIGNUM * x, BIGNUM * y)
{
BN_CTX * ctx = BN_CTX_new ();
m_Group = EC_GROUP_new_curve_GFp (p, a, b, ctx);
EC_POINT * P = EC_POINT_new (m_Group);
EC_POINT_set_affine_coordinates_GFp (m_Group, P, x, y, ctx);
EC_GROUP_set_generator (m_Group, P, q, nullptr);
EC_GROUP_set_curve_name (m_Group, NID_id_GostR3410_2001);
EC_POINT_free(P);
BN_CTX_free (ctx);
}
GOSTR3410Curve::~GOSTR3410Curve ()
{
EC_GROUP_free (m_Group);
}
EC_POINT * GOSTR3410Curve::MulP (const BIGNUM * n) const
{
BN_CTX * ctx = BN_CTX_new ();
auto p = EC_POINT_new (m_Group);
EC_POINT_mul (m_Group, p, n, nullptr, nullptr, ctx);
BN_CTX_free (ctx);
return p;
}
bool GOSTR3410Curve::GetXY (const EC_POINT * p, BIGNUM * x, BIGNUM * y) const
{
return EC_POINT_get_affine_coordinates_GFp (m_Group, p, x, y, nullptr);
}
EC_POINT * GOSTR3410Curve::CreatePoint (const BIGNUM * x, const BIGNUM * y) const
{
EC_POINT * p = EC_POINT_new (m_Group);
EC_POINT_set_affine_coordinates_GFp (m_Group, p, x, y, nullptr);
return p;
}
void GOSTR3410Curve::Sign (const BIGNUM * priv, const BIGNUM * digest, BIGNUM * r, BIGNUM * s)
{
BN_CTX * ctx = BN_CTX_new ();
BN_CTX_start (ctx);
BIGNUM * q = BN_CTX_get (ctx);
EC_GROUP_get_order(m_Group, q, ctx);
BIGNUM * k = BN_CTX_get (ctx);
BN_rand_range (k, q); // 0 < k < q
EC_POINT * C = MulP (k); // C = k*P
GetXY (C, r, nullptr); // r = Cx
EC_POINT_free (C);
BN_mod_mul (s, r, priv, q, ctx); // (r*priv)%q
BIGNUM * tmp = BN_CTX_get (ctx);
BN_mod_mul (tmp, k, digest, q, ctx); // (k*digest)%q
BN_mod_add (s, s, tmp, q, ctx); // (r*priv+k*digest)%q
BN_CTX_end (ctx);
BN_CTX_free (ctx);
}
bool GOSTR3410Curve::Verify (const EC_POINT * pub, const BIGNUM * digest, const BIGNUM * r, const BIGNUM * s)
{
BN_CTX * ctx = BN_CTX_new ();
BN_CTX_start (ctx);
BIGNUM * q = BN_CTX_get (ctx);
EC_GROUP_get_order(m_Group, q, ctx);
BIGNUM * h = BN_CTX_get (ctx);
BN_mod (h, digest, q, ctx); // h = digest % q
BN_mod_inverse (h, h, q, ctx); // 1/h mod q
BIGNUM * z1 = BN_CTX_get (ctx);
BN_mod_mul (z1, s, h, q, ctx); // z1 = s/h
BIGNUM * z2 = BN_CTX_get (ctx);
BN_sub (z2, q, r); // z2 = -r
BN_mod_mul (z2, z2, h, q, ctx); // z2 = -r/h
EC_POINT * C = EC_POINT_new (m_Group);
EC_POINT_mul (m_Group, C, z1, pub, z2, ctx); // z1*P + z2*pub
BIGNUM * x = BN_CTX_get (ctx);
GetXY (C, x, nullptr); // Cx
BN_mod (x, x, q, ctx); // Cx % q
bool ret = !BN_cmp (x, r); // Cx = r ?
EC_POINT_free (C);
BN_CTX_end (ctx);
BN_CTX_free (ctx);
return ret;
}
static GOSTR3410Curve * CreateGOSTR3410Curve (GOSTR3410ParamSet paramSet)
{
// a, b, p, q, x, y
static const char * params[eGOSTR3410NumParamSets][6] =
{
{
"FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFD94",
"A6",
"FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFD97",
"FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF6C611070995AD10045841B09B761B893",
"1",
"8D91E471E0989CDA27DF505A453F2B7635294F2DDF23E3B122ACC99C9E9F1E14"
}, // A
{
"8000000000000000000000000000000000000000000000000000000000000C96",
"3E1AF419A269A5F866A7D3C25C3DF80AE979259373FF2B182F49D4CE7E1BBC8B",
"8000000000000000000000000000000000000000000000000000000000000C99",
"800000000000000000000000000000015F700CFFF1A624E5E497161BCC8A198F",
"1",
"3FA8124359F96680B83D1C3EB2C070E5C545C9858D03ECFB744BF8D717717EFC"
}, // B
{
"9B9F605F5A858107AB1EC85E6B41C8AACF846E86789051D37998F7B9022D7598",
"805A",
"9B9F605F5A858107AB1EC85E6B41C8AACF846E86789051D37998F7B9022D759B",
"9B9F605F5A858107AB1EC85E6B41C8AA582CA3511EDDFB74F02F3A6598980BB9",
"0",
"41ECE55743711A8C3CBF3783CD08C0EE4D4DC440D4641A8F366E550DFDB3BB67"
} // C
};
BIGNUM * a = nullptr, * b = nullptr, * p = nullptr, * q =nullptr, * x = nullptr, * y = nullptr;
BN_hex2bn(&a, params[paramSet][0]);
BN_hex2bn(&b, params[paramSet][1]);
BN_hex2bn(&p, params[paramSet][2]);
BN_hex2bn(&q, params[paramSet][3]);
BN_hex2bn(&x, params[paramSet][4]);
BN_hex2bn(&y, params[paramSet][5]);
auto curve = new GOSTR3410Curve (a, b, p, q, x, y);
BN_free (a); BN_free (b); BN_free (p); BN_free (q); BN_free (x); BN_free (y);
return curve;
}
static std::array<std::unique_ptr<GOSTR3410Curve>, eGOSTR3410NumParamSets> g_GOSTR3410Curves;
std::unique_ptr<GOSTR3410Curve>& GetGOSTR3410Curve (GOSTR3410ParamSet paramSet)
{
if (!g_GOSTR3410Curves[paramSet])
{
auto c = CreateGOSTR3410Curve (paramSet);
if (!g_GOSTR3410Curves[paramSet]) // make sure it was not created already
g_GOSTR3410Curves[paramSet].reset (c);
else
delete c;
}
return g_GOSTR3410Curves[paramSet];
}
}
}