NAME         top

       gnutls_srp_set_server_credentials_function - API function

SYNOPSIS         top

       #include <gnutls/gnutls.h>

       cred, gnutls_srp_server_credentials_function         * func);

ARGUMENTS         top

       gnutls_srp_server_credentials_t         cred
                   is a gnutls_srp_server_credentials_t type.

       gnutls_srp_server_credentials_function         * func
                   is the callback function

DESCRIPTION         top

       This function can be used to set a callback to retrieve the user's
       SRP credentials.  The callback's function form is:

       int (*callback)(gnutls_session_t, const char* username,
       gnutls_datum_t *salt, gnutls_datum_t *verifier, gnutls_datum_t
       *generator, gnutls_datum_t *prime);

        username contains the actual username.  The  salt ,  verifier ,
       generator and  prime must be filled in using the gnutls_malloc(). For
       convenience  prime and  generator may also be one of the static
       parameters defined in gnutls.h.

       Initially, the data field is NULL in every gnutls_datum_t structure
       that the callback has to fill in. When the callback is done GnuTLS
       deallocates all of those buffers which are non-NULL, regardless of
       the return value.

       In order to prevent attackers from guessing valid usernames, if a
       user does not exist, g and n values should be filled in using a
       random user's parameters. In that case the callback must return the
       special value (1).  See gnutls_srp_set_server_fake_salt_seed too.  If
       this is not required for your application, return a negative number
       from the callback to abort the handshake.

       The callback function will only be called once per handshake.  The
       callback function should return 0 on success, while -1 indicates an

REPORTING BUGS         top

       Report bugs to <>.
       Home page:

COPYRIGHT         top

       Copyright © 2001-2018 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

       This page is part of the GnuTLS (GnuTLS Transport Layer Security
       Library) project.  Information about the project can be found at 
       ⟨⟩.  If you have a bug report for this manual
       page, send it to  This page was obtained from the
       tarball gnutls-3.6.2.tar.xz fetched from
       ⟨⟩ on 2018-04-30.  If you discover
       any rendering problems in this HTML version of the page, or you
       believe there is a better or more up-to-date source for the page, or
       you have corrections or improvements to the information in this
       COLOPHON (which is not part of the original manual page), send a mail

gnutls                         gnutl3s._6s.r2p_set_server_credentials_function(3)