gnutls_prf(3)                        gnutls                        gnutls_prf(3)

       gnutls_prf - API function

       #include <gnutls/gnutls.h>

       int gnutls_prf(gnutls_session_t session, size_t label_size, const char *
       label, int server_random_first, size_t extra_size, const char * extra,
       size_t outsize, char * out);

       gnutls_session_t session
                   is a gnutls_session_t type.

       size_t label_size
                   length of the  label variable.

       const char * label
                   label used in PRF computation, typically a short string.

       int server_random_first
                   non-zero if server random field should be first in seed

       size_t extra_size
                   length of the  extra variable.

       const char * extra
                   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.

       Applies the TLS Pseudo-Random-Function (PRF) on the master secret and the
       provided data, seeded with the client and server random fields.  For the
       key expansion specified in RFC5705 see gnutls_prf_rfc5705().

       The  label variable usually contains a string denoting the purpose for
       the generated data.  The  server_random_first indicates whether the
       client random field or the server random field should be first in the
       seed.  Non-zero indicates that the server random field is first, 0 that
       the client random field is first.

       The  extra variable can be used to add more data to the seed, after the
       random variables.  It can be used to make sure the generated output is
       strongly connected to some additional data (e.g., a string used in user

       The output is placed in  out , which must be pre-allocated.

       This function produces identical output with gnutls_prf_rfc5705() when
       server_random_first is set to 0 and  extra is NULL. Under TLS1.3 this
       function will only operate when these conditions are true, or otherwise

       GNUTLS_E_SUCCESS on success, or an error code.

       Report bugs to <>.
       Home page:

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       Copying and distribution of this file, with or without modification, are
       permitted in any medium without royalty provided the copyright notice and
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       The full documentation for gnutls is maintained as a Texinfo manual.  If
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gnutls                               3.6.13                        gnutls_prf(3)