SSL_export_keying_material(3)

NAME

       SSL_export_keying_material - obtain keying material for application use

SYNOPSIS

        #include <openssl/ssl.h>

        int SSL_export_keying_material(SSL *s, unsigned char *out, size_t olen,
                                       const char *label, size_t llen,
                                       const unsigned char *context,
                                       size_t contextlen, int use_context);

DESCRIPTION

       During the creation of a TLS or DTLS connection shared keying material
       is established between the two endpoints. The function SSL_export_key-
       ing_material() enables an application to use some of this keying mate-
       rial for its own purposes in accordance with RFC5705.

       An application may need to securely establish the context within which
       this keying material will be used. For example this may include identi-
       fiers for the application session, application algorithms or parame-
       ters, or the lifetime of the context. The context value is left to the
       application but must be the same on both sides of the communication.

       For a given SSL connection s, olen bytes of data will be written to
       out. The application specific context should be supplied in the loca-
       tion pointed to by context and should be contextlen bytes long. Provi-
       sion of a context is optional. If the context should be omitted
       entirely then use_context should be set to 0. Otherwise it should be
       any other value. If use_context is 0 then the values of context and
       contextlen are ignored.  Note that a zero length context is treated
       differently to no context at all, and will result in different keying
       material being returned.

       An application specific label should be provided in the location
       pointed to by label and should be llen bytes long. Typically this will
       be a value from the IANA Exporter Label Registry
       (<https://www.iana.org/assignments/tls-parameters/tls-parame-
       ters.xhtml#exporter-labels>).  Alternatively labels beginning with
       "EXPERIMENTAL" are permitted by the standard to be used without regis-
       tration.

       Note that this function is only defined for TLSv1.0 and above, and
       DTLSv1.0 and above. Attempting to use it in SSLv3 will result in an
       error.

RETURN VALUES

       SSL_export_keying_material() returns 0 or -1 on failure or 1 on suc-
       cess.

COPYRIGHT

       Copyright 2017 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the OpenSSL license (the "License").  You may not use
       this file except in compliance with the License.  You can obtain a copy
       in the file LICENSE in the source distribution or at
       <https://www.openssl.org/source/license.html>.

1.0.2t                            2019-09-10     SSL_export_keying_material(3)