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/*
* GMP NR Engine
* (C) 1999-2007 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#include <botan/eng_gmp.h>
#include <botan/gmp_wrap.h>
#include <gmp.h>
namespace Botan {
#if defined(BOTAN_HAS_NYBERG_RUEPPEL)
namespace {
/*
* GMP NR Operation
*/
class GMP_NR_Op : public NR_Operation
{
public:
SecureVector<byte> verify(const byte[], u32bit) const;
SecureVector<byte> sign(const byte[], u32bit, const BigInt&) const;
NR_Operation* clone() const { return new GMP_NR_Op(*this); }
GMP_NR_Op(const DL_Group& group, const BigInt& y1, const BigInt& x1) :
x(x1), y(y1), p(group.get_p()), q(group.get_q()), g(group.get_g()) {}
private:
const GMP_MPZ x, y, p, q, g;
};
/*
* GMP NR Verify Operation
*/
SecureVector<byte> GMP_NR_Op::verify(const byte sig[], u32bit sig_len) const
{
const u32bit q_bytes = q.bytes();
if(sig_len != 2*q_bytes)
return false;
GMP_MPZ c(sig, q_bytes);
GMP_MPZ d(sig + q_bytes, q_bytes);
if(mpz_cmp_ui(c.value, 0) <= 0 || mpz_cmp(c.value, q.value) >= 0 ||
mpz_cmp(d.value, q.value) >= 0)
throw Invalid_Argument("GMP_NR_Op::verify: Invalid signature");
GMP_MPZ i1, i2;
mpz_powm(i1.value, g.value, d.value, p.value);
mpz_powm(i2.value, y.value, c.value, p.value);
mpz_mul(i1.value, i1.value, i2.value);
mpz_mod(i1.value, i1.value, p.value);
mpz_sub(i1.value, c.value, i1.value);
mpz_mod(i1.value, i1.value, q.value);
return BigInt::encode(i1.to_bigint());
}
/*
* GMP NR Sign Operation
*/
SecureVector<byte> GMP_NR_Op::sign(const byte in[], u32bit length,
const BigInt& k_bn) const
{
if(mpz_cmp_ui(x.value, 0) == 0)
throw Internal_Error("GMP_NR_Op::sign: No private key");
GMP_MPZ f(in, length);
GMP_MPZ k(k_bn);
if(mpz_cmp(f.value, q.value) >= 0)
throw Invalid_Argument("GMP_NR_Op::sign: Input is out of range");
GMP_MPZ c, d;
mpz_powm(c.value, g.value, k.value, p.value);
mpz_add(c.value, c.value, f.value);
mpz_mod(c.value, c.value, q.value);
mpz_mul(d.value, x.value, c.value);
mpz_sub(d.value, k.value, d.value);
mpz_mod(d.value, d.value, q.value);
if(mpz_cmp_ui(c.value, 0) == 0)
throw Internal_Error("Default_NR_Op::sign: c was zero");
const u32bit q_bytes = q.bytes();
SecureVector<byte> output(2*q_bytes);
c.encode(output, q_bytes);
d.encode(output + q_bytes, q_bytes);
return output;
}
}
/*
* Acquire a NR op
*/
NR_Operation* GMP_Engine::nr_op(const DL_Group& group, const BigInt& y,
const BigInt& x) const
{
return new GMP_NR_Op(group, y, x);
}
#endif
}
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