gnutls_prf_raw — API function


#include <gnutls/gnutls.h>
int gnutls_prf_raw( gnutls_session_t session,
  size_t label_size,
  const char * label,
  size_t seed_size,
  const char * seed,
  size_t outsize,
  char * out);


gnutls_session_t session

is a gnutls_session_t structure.

size_t label_size

length of the label variable.

const char * label

label used in PRF computation, typically a short string.

size_t seed_size

length of the seed variable.

const char * seed

optional extra data to seed the PRF with.

size_t outsize

size of pre−allocated output buffer to hold the output.

char * out

pre−allocated buffer to hold the generated data.


Apply the TLS Pseudo−Random−Function (PRF) on the master secret and the provided data.

The label variable usually contains a string denoting the purpose for the generated data. The seed usually contains data such as the client and server random, perhaps together with some additional data that is added to guarantee uniqueness of the output for a particular purpose.

Because the output is not guaranteed to be unique for a particular session unless seed includes the client random and server random fields (the PRF would output the same data on another connection resumed from the first one), it is not recommended to use this function directly. The gnutls_prf() function seeds the PRF with the client and server random fields directly, and is recommended if you want to generate pseudo random data unique for each session.


GNUTLS_E_SUCCESS on success, or an error code.


Report bugs to <>.

General guidelines for reporting bugs:

GnuTLS home page:


The full documentation for gnutls is maintained as a Texinfo manual. If the info and gnutls programs are properly installed at your site, the command

info gnutls

should give you access to the complete manual. As an alternative you may obtain the manual from:


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