---
name: "gnutls_x509_crt_set_serial"
section: "3"
platform: "linux"
package: "gnutls"
version: "3.8.13-3"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/gnutls_x509_crt_set_serial"
---

# gnutls\_x509\_crt\_set\_serial(3)

API function

## NAME

gnutls\_x509\_crt\_set\_serial - API function

## SYNOPSIS

**#include \<gnutls/x509.h\>**

**int gnutls\_x509\_crt\_set\_serial(gnutls\_x509\_crt\_t** *cert***, const void \*** *serial***, size\_t** *serial\_size***);**

## ARGUMENTS

- gnutls\_x509\_crt\_t cert

  a certificate of type **gnutls\_x509\_crt\_t**

- const void \* serial

  The serial number

- size\_t serial\_size

  Holds the size of the serial field.

## DESCRIPTION

This function will set the X.509 certificate's serial number. While the serial number is an integer, it is often handled as an opaque field by several CAs. For this reason this function accepts any kind of data as a serial number. To be consistent with the X.509/PKIX specifications the provided  *serial* should be  a big-endian positive number (i.e. its leftmost bit should be zero).

The size of the serial is restricted to 20 bytes maximum by RFC5280. This function allows writing more than 20 bytes but the generated certificates in that case may be rejected by other implementations.

## RETURNS

On success, **GNUTLS\_E\_SUCCESS** (0) is returned, otherwise a negative error value.

## REPORTING BUGS

Report bugs to \<bugs@gnutls.org\>.\
 Home page: https://www.gnutls.org

## COPYRIGHT

Copyright © 2001-2023 Free Software Foundation, Inc., and others.\
 Copying and distribution of this file, with or without modification, are permitted in any medium without royalty provided the copyright notice and this notice are preserved.

## SEE ALSO

The full documentation for **gnutls** is maintained as a Texinfo manual. If the /usr/share/doc/gnutls/ directory does not contain the HTML form visit

- https://www.gnutls.org/manual/