// generates new public and secret keys
void PublicKeyGen(Integer secretKey, Integer& publicKeyX, Integer& publicKeyY)
{
Integer q;
ECP ec;
ECPPoint G, Q;
LoadSECP256r1Curve(q, ec, G);
Q = ec.ScalarMultiply(G, secretKey);
publicKeyX = Q.x;
publicKeyY = Q.y;
}
void Sign(Integer& sigE, Integer& sigS, const Integer& secretKey,
const byte* message, int mlen, AutoSeededRandomPool& rng)
{
Integer q,k;
ECP ec;
ECPPoint G, r;
LoadSECP256r1Curve(q, ec, G);
k = Integer(rng, 256) % q; // choose random k
r = ec.ScalarMultiply(G, k); // r = G^k
sigE = HashPointMessage(ec, r, message, mlen) % q; // e = H(M||r)
sigS = (k - secretKey*sigE) % q;
}
// generates new public and secret keys
void KeyGen(Integer& secretKey, Integer& publicKeyX, Integer& publicKeyY, AutoSeededRandomPool& rng)
{
Integer q;
ECP ec;
ECPPoint G, Q;
LoadSECP256r1Curve(q, ec, G);
secretKey = Integer(rng, 256) % q;
Q = ec.ScalarMultiply(G, secretKey);
publicKeyX = Q.x;
publicKeyY = Q.y;
}
NAMESPACE_END
ECP::ECP(const ECP &ecp, bool convertToMontgomeryRepresentation)
{
if (convertToMontgomeryRepresentation && !ecp.GetField().IsMontgomeryRepresentation())
{
m_fieldPtr.reset(new MontgomeryRepresentation(ecp.GetField().GetModulus()));
m_a = GetField().ConvertIn(ecp.m_a);
m_b = GetField().ConvertIn(ecp.m_b);
}
else
operator=(ecp);
}
bool Verify(const Integer& publicKeyX, const Integer& publicKeyY,
const Integer& sigE, const Integer& sigS,
const byte* message,int mlen)
{
Integer q, sigEv;
ECP ec;
ECPPoint G, rv, Q;
LoadSECP256r1Curve(q, ec, G);
Q = ECPPoint(publicKeyX,publicKeyY);
rv = ec.CascadeScalarMultiply(G, sigS, Q, sigE); // r = G^s.Q^e
sigEv = HashPointMessage(ec, rv, message, mlen) % q;
return (sigE == sigEv);
}
Integer HashPointMessage(const ECP& ec, const ECPPoint& R,
const byte* message, int mlen, bool compress = false)
{
const int digestsize = 256/8;
SHA3 sha(digestsize);
int len = ec.EncodedPointSize();
byte *buffer = new byte[len];
ec.EncodePoint(buffer, R, compress);
sha.Update(buffer, len);
delete[] buffer;
sha.Update(message, mlen);
byte digest[digestsize];
sha.Final(digest);
Integer ans;
ans.Decode(digest, digestsize);
return ans;
}
void EcPrecomputation<ECP>::SetCurveAndBase(const ECP &ec, const ECP::Point &base)
{
m_mr.reset(new MontgomeryRepresentation(ec.GetField().GetModulus()));
m_ec.reset(new ECP(*m_mr, m_mr->ConvertIn(ec.GetA()), m_mr->ConvertIn(ec.GetB())));
m_ep.SetGroupAndBase(*m_ec, ToMontgomery(*m_mr, base));
}
