X509_get0_pubkey_bitstr
ikey = X509_get0_pubkey_bitstr(issuer);
if ((ikey = X509_get0_pubkey_bitstr(issuer)) == NULL)
key = X509_get0_pubkey_bitstr(data);
ASN1_BIT_STRING *X509_get0_pubkey_bitstr(const X509 *x);