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/*
* (C) 2015,2016 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#ifndef ECC_HELPERS_H__
#define ECC_HELPERS_H__
#include "driver.h"
#include <botan/curve_gfp.h>
#include <botan/ec_group.h>
#include <botan/reducer.h>
void check_redc(std::function<void (BigInt&, secure_vector<word>&)> redc_fn,
const Modular_Reducer& redc,
const BigInt& prime,
const BigInt& x)
{
const Botan::BigInt v1 = x % prime;
const Botan::BigInt v2 = redc.reduce(x);
Botan::secure_vector<Botan::word> ws;
Botan::BigInt v3 = x;
redc_fn(v3, ws);
FUZZER_ASSERT_EQUAL(v1, v2);
FUZZER_ASSERT_EQUAL(v2, v3);
}
inline std::ostream& operator<<(std::ostream& o, const PointGFp& point)
{
o << point.get_affine_x() << "," << point.get_affine_y();
return o;
}
void check_ecc_math(const EC_Group& group,
const uint8_t in[], size_t len)
{
// These depend only on the group, which is also static
static const Botan::PointGFp base_point = group.get_base_point();
static Botan::Blinded_Point_Multiply blind(base_point, group.get_order(), 4);
const size_t hlen = len / 2;
const BigInt a = BigInt::decode(in, hlen);
const BigInt b = BigInt::decode(in + hlen, len - hlen);
const Botan::BigInt c = a + b;
const Botan::PointGFp P = base_point * a;
const Botan::PointGFp Q = base_point * b;
const Botan::PointGFp R = base_point * c;
const Botan::PointGFp A1 = P + Q;
const Botan::PointGFp A2 = Q + P;
FUZZER_ASSERT_EQUAL(A1, A2);
const Botan::PointGFp P1 = blind.blinded_multiply(a, fuzzer_rng());
const Botan::PointGFp Q1 = blind.blinded_multiply(b, fuzzer_rng());
const Botan::PointGFp R1 = blind.blinded_multiply(c, fuzzer_rng());
const Botan::PointGFp S1 = P1 + Q1;
const Botan::PointGFp S2 = Q1 + P1;
FUZZER_ASSERT_EQUAL(S1, S2);
FUZZER_ASSERT_EQUAL(S1, A1);
}
#endif
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