Except D isn't C.
OpenSSL is terribly undocumented. I'm currently looking at checking transaction ECDSA signatures using:
bool (*ecdsaVerify)(u_int8_t *,u_int8_t *,const u_int8_t *); /**< Function for verifying ECDSA signatures for a 70 byte signature against a 32 byte hash using a 66 byte ECDSA public key. */
The first parameter is the 70 byte signature, the second is the 32 byte SHA256 digest and the last is the public key data. For testing I need to implement this function. I'm using OpenSSL for the tests but it doesn't document converting public key bytes to an EC_KEY object. Not good at all! But I looked at the bitcoin source code and I saw o2i_ECPublicKey so I'll use that...
bool ecdsaVerify(u_int8_t * signature,u_int8_t * hash,const u_int8_t * pubKey){
EC_KEY * key = EC_KEY_new_by_curve_name(NID_secp256k1);
o2i_ECPublicKey(&key, &pubKey, 66);
ECDSA_verify(0, hash, 32, signature, 70, key);
}
Hopefully this is the right way. Am I right thinking that the signatures are 70 bytes and the public keys are 66 bytes?
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