bool crypto_ops::generate_key_derivation(const public_key &key1, const secret_key &key2, key_derivation &derivation) {
ge_p3 point;
ge_p2 point2;
ge_p1p1 point3;
assert(sc_check(&key2) == 0);
if (ge_frombytes_vartime(&point, &key1) != 0) {
return false;
}
ge_scalarmult(&point2, &key2, &point);
ge_mul8(&point3, &point2);
ge_p1p1_to_p2(&point2, &point3);
ge_tobytes(&derivation, &point2);
return true;
}
int crypto_sign_edwards25519sha512batch_open(unsigned char *m,
unsigned long long *mlen_p,
const unsigned char *sm,
unsigned long long smlen,
const unsigned char *pk)
{
unsigned char h[64];
unsigned char t1[32], t2[32];
unsigned long long mlen;
ge_cached Ai;
ge_p1p1 csa;
ge_p2 cs;
ge_p3 A;
ge_p3 R;
ge_p3 cs3;
*mlen_p = 0;
if (smlen < 64 || smlen > SIZE_MAX) {
return -1;
}
mlen = smlen - 64;
if (sm[smlen - 1] & 224) {
return -1;
}
if (ge_frombytes_negate_vartime(&A, pk) != 0 ||
ge_frombytes_negate_vartime(&R, sm) != 0) {
return -1;
}
ge_p3_to_cached(&Ai, &A);
crypto_hash_sha512(h, sm, mlen + 32);
sc_reduce(h);
ge_scalarmult_vartime(&cs3, h, &R);
ge_add(&csa, &cs3, &Ai);
ge_p1p1_to_p2(&cs, &csa);
ge_tobytes(t1, &cs);
t1[31] ^= 1 << 7;
ge_scalarmult_base(&R, sm + 32 + mlen);
ge_p3_tobytes(t2, &R);
if (crypto_verify_32(t1, t2) != 0) {
return -1;
}
*mlen_p = mlen;
memmove(m, sm + 32, mlen);
return 0;
}
bool crypto_ops::derive_public_key(const key_derivation &derivation, size_t output_index,
const public_key &base, public_key &derived_key) {
ec_scalar scalar;
ge_p3 point1;
ge_p3 point2;
ge_cached point3;
ge_p1p1 point4;
ge_p2 point5;
if (ge_frombytes_vartime(&point1, &base) != 0) {
return false;
}
derivation_to_scalar(derivation, output_index, scalar);
ge_scalarmult_base(&point2, &scalar);
ge_p3_to_cached(&point3, &point2);
ge_add(&point4, &point1, &point3);
ge_p1p1_to_p2(&point5, &point4);
ge_tobytes(&derived_key, &point5);
return true;
}
