X509_get_serialNumber, X509_get0_serialNumber, X509_set_serialNumber - get or
  set certificate serial number
 #include <openssl/x509.h>
 ASN1_INTEGER *X509_get_serialNumber(X509 *x);
 const ASN1_INTEGER *X509_get0_serialNumber(const X509 *x);
 int X509_set_serialNumber(X509 *x, ASN1_INTEGER *serial);
X509_get_serialNumber() returns the serial number of certificate x
  as an ASN1_INTEGER structure which can be examined or initialised. The
  value returned is an internal pointer which MUST NOT be freed up after
  the call.
X509_get0_serialNumber() is the same as
    X509_get_serialNumber() except it accepts a const parameter and
    returns a const result.
X509_set_serialNumber() sets the serial number of
    certificate x to serial. A copy of the serial number is used
    internally so serial should be freed up after use.
X509_get_serialNumber() and X509_get0_serialNumber() return an
  ASN1_INTEGER structure.
X509_set_serialNumber() returns 1 for success and 0 for
    failure.
d2i_X509(3), ERR_get_error(3), X509_CRL_get0_by_serial(3),
  X509_get0_signature(3), X509_get_ext_d2i(3),
  X509_get_extension_flags(3), X509_get_pubkey(3),
  X509_get_subject_name(3), X509_NAME_add_entry_by_txt(3),
  X509_NAME_ENTRY_get_object(3), X509_NAME_get_index_by_NID(3),
  X509_NAME_print_ex(3), X509_new(3), X509_sign(3),
  X509V3_get_d2i(3), X509_verify_cert(3)
The X509_get_serialNumber() and X509_set_serialNumber() functions
  are available in all versions of OpenSSL. The X509_get0_serialNumber()
  function was added in OpenSSL 1.1.0.
Copyright 2016 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the OpenSSL license (the "License"). You
    may not use this file except in compliance with the License. You can obtain
    a copy in the file LICENSE in the source distribution or at
    <https://www.openssl.org/source/license.html>.