gnutls\_x509\_crt\_get\_subject\_key\_id(3) gnutls gnutls\_x509\_crt\_get\_subject\_key\_id(3)

# [NAME](#NAME)

gnutls\_x509\_crt\_get\_subject\_key\_id - API function

# [SYNOPSIS](#SYNOPSIS)

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

**int gnutls\_x509\_crt\_get\_subject\_key\_id(gnutls\_x509\_crt\_t cert, void * ret, size\_t * ret\_size, unsigned int * critical);**

# [ARGUMENTS](#ARGUMENTS)

[gnutls\_x509\_crt\_t cert](#gnutls_x509_crt_t)

should contain a **gnutls\_x509\_crt\_t** type

[void * ret](#void)

The place where the identifier will be copied

[size\_t * ret\_size](#size_t)

Holds the size of the result field.

[unsigned int * critical](#unsigned)

will be non-zero if the extension is marked as critical (may be null)

# [DESCRIPTION](#DESCRIPTION)

This function will return the X.509v3 certificate's subject key identifier. This is obtained by the X.509 Subject Key identifier extension field (2.5.29.14).

# [RETURNS](#RETURNS)

On success, **GNUTLS\_E\_SUCCESS** (0) is returned, **GNUTLS\_E\_REQUESTED\_DATA\_NOT\_AVAILABLE** if the extension is not present, otherwise a negative error value.

# [REPORTING BUGS](#REPORTING_BUGS)

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

# [COPYRIGHT](#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](#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/](https://www.gnutls.org/manual/)

3.8.13 gnutls

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Document: gnutls_x509_crt_get_subject_key_id(3) from gnutls 3.8.13-r1 (Chainguard OS)
Source: https://gitlab.com/gnutls/gnutls