gnutls_prf_early(3) — Linux manual page


gnutls_prf_early(3)              gnutls              gnutls_prf_early(3)

NAME         top

       gnutls_prf_early - API function

SYNOPSIS         top

       #include <gnutls/gnutls.h>

       int gnutls_prf_early(gnutls_session_t session, size_t label_size,
       const char * label, size_t context_size, const char * context,
       size_t outsize, char * out);

ARGUMENTS         top

       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

       size_t context_size
                   length of the  extra variable.

       const char * context
                   optional extra data to seed the PRF with.

       size_t outsize
                   size of pre-allocated output buffer to hold the

       char * out  pre-allocated buffer to hold the generated data.

DESCRIPTION         top

       This function is similar to gnutls_prf_rfc5705(), but only works
       in TLS 1.3 or later to export early keying material.

       Note that the keying material is only available after the
       ClientHello message is processed and before the application
       traffic keys are established.  Therefore this function shall be
       called in a handshake hook function for

       The  label variable usually contains a string denoting the
       purpose for the generated data.

       The  context 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 authentication).

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

       Note that, to provide the RFC5705 context, the  context variable
       must be non-null.

RETURNS         top

       GNUTLS_E_SUCCESS on success, or an error code.

SINCE         top


REPORTING BUGS         top

       Report bugs to <>.
       Home page:

COPYRIGHT         top

       Copyright © 2001- 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         top

       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 

COLOPHON         top

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gnutls                            3.7.8              gnutls_prf_early(3)