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NAME

       DH_generate_key, DH_compute_key - perform Diffie-Hellman key exchange

SYNOPSIS

        #include <openssl/dh.h>

        int DH_generate_key(DH *dh);

        int DH_compute_key(unsigned char *key, BIGNUM *pub_key, DH *dh);

DESCRIPTION

       DH_generate_key() performs the first step of a Diffie-Hellman key exchange by generating
       private and public DH values. By calling DH_compute_key(), these are combined with the
       other party's public value to compute the shared key.

       DH_generate_key() expects dh to contain the shared parameters dh->p and dh->g. It
       generates a random private DH value unless dh->priv_key is already set, and computes the
       corresponding public value dh->pub_key, which can then be published.

       DH_compute_key() computes the shared secret from the private DH value in dh and the other
       party's public value in pub_key and stores it in key. key must point to DH_size(dh) bytes
       of memory.

RETURN VALUES

       DH_generate_key() returns 1 on success, 0 otherwise.

       DH_compute_key() returns the size of the shared secret on success, -1 on error.

       The error codes can be obtained by ERR_get_error(3).

SEE ALSO

       DH_new(3), ERR_get_error(3), RAND_bytes(3), DH_size(3)

COPYRIGHT

       Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the Apache License 2.0 (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>.