PKCS7_get_issuer_and_serial
LCRYPTO_USED(PKCS7_get_issuer_and_serial);
LCRYPTO_ALIAS(PKCS7_get_issuer_and_serial);
PKCS7_ISSUER_AND_SERIAL *PKCS7_get_issuer_and_serial(PKCS7 *p7, int idx);