X509_pubkey_digest
X509_pubkey_digest(signer, EVP_sha1(), md, NULL);
X509_pubkey_digest(x, EVP_sha1(), tmphash, NULL);
X509_pubkey_digest(cert, dgst, md, NULL);
int X509_pubkey_digest(const X509 *data,const EVP_MD *type,
if (X509_pubkey_digest(cert, EVP_sha256(), d, &dlen) != 1)