Cryptography and SSL/TLS Toolkit



DH_generate_key, DH_compute_key - perform Diffie-Hellman key exchange


 #include <openssl/dh.h>

 int DH_generate_key(DH *dh);

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


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.


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).


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

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