gnutls_prf_early - Man Page

API function

Synopsis

#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

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.

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 output.

char * out

pre-allocated buffer to hold the generated data.

Description

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 GNUTLS_HANDSHAKE_CLIENT_HELLO.

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

GNUTLS_E_SUCCESS on success, or an error code.

Since

3.6.8

Reporting Bugs

Report bugs to <bugs@gnutls.org>.
Home page: https://www.gnutls.org

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/

Info

3.7.1 gnutls