---
name: "gnutls_x509_privkey_sign_data"
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_privkey_sign_data"
---

# gnutls\_x509\_privkey\_sign\_data(3)

API function

## NAME

gnutls\_x509\_privkey\_sign\_data - API function

## SYNOPSIS

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

**int gnutls\_x509\_privkey\_sign\_data(gnutls\_x509\_privkey\_t** *key***, gnutls\_digest\_algorithm\_t** *digest***, unsigned int** *flags***, const gnutls\_datum\_t \*** *data***, void \*** *signature***, size\_t \*** *signature\_size***);**

## ARGUMENTS

- gnutls\_x509\_privkey\_t key

  a key

- gnutls\_digest\_algorithm\_t digest

  should be a digest algorithm

- unsigned int flags

  should be 0 for now

- const gnutls\_datum\_t \* data

  holds the data to be signed

- void \* signature

  will contain the signature

- size\_t \* signature\_size

  holds the size of signature (and will be replaced by the new size)

## DESCRIPTION

This function will sign the given data using a signature algorithm supported by the private key. Signature algorithms are always used together with a hash functions.  Different hash functions may be used for the RSA algorithm, but only SHA-1 for the DSA keys.

If the buffer provided is not long enough to hold the output, then \* *signature\_size* is updated and **GNUTLS\_E\_SHORT\_MEMORY\_BUFFER** will be returned.

Use **gnutls\_x509\_crt\_get\_preferred\_hash\_algorithm()** to determine the hash algorithm.

## 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/