---
name: "gnutls_x509_crt_get_issuer_unique_id"
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_get_issuer_unique_id"
---

# gnutls\_x509\_crt\_get\_issuer\_unique\_id(3)

API function

## NAME

gnutls\_x509\_crt\_get\_issuer\_unique\_id - API function

## SYNOPSIS

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

**int gnutls\_x509\_crt\_get\_issuer\_unique\_id(gnutls\_x509\_crt\_t** *crt***, char \*** *buf***, size\_t \*** *buf\_size***);**

## ARGUMENTS

- gnutls\_x509\_crt\_t crt

  Holds the certificate

- char \* buf

  user allocated memory buffer, will hold the unique id

- size\_t \* buf\_size

  size of user allocated memory buffer (on input), will hold actual size of the unique ID on return.

## DESCRIPTION

This function will extract the issuerUniqueID value (if present) for the given certificate.

If the user allocated memory buffer is not large enough to hold the full subjectUniqueID, then a GNUTLS\_E\_SHORT\_MEMORY\_BUFFER error will be returned, and buf\_size will be set to the actual length.

This function had a bug prior to 3.4.8 that prevented the setting of **NULL**  *buf* to discover the  *buf\_size* . To use this function safely with the older versions the  *buf* must be a valid buffer that can hold at least a single byte if  *buf\_size* is zero.

## RETURNS

**GNUTLS\_E\_SUCCESS** on success, otherwise a negative error code.

## SINCE

2\.12.0

## 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/