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(3), ERR_get_error(3), rand(3), DH_size(3)
HISTORY
DH_generate_key() and DH_compute_key() are available in all
versions of SSLeay and OpenSSL.
