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, or
0 otherwise.
DH_compute_key() returns the size of the
shared secret on success, or -1 on error.
The error codes can be obtained by ERR_get_error(3).
SEE ALSO
DH_get0_key(3), DH_new(3), DH_size(3), ERR_get_error(3), RAND_bytes(3)
HISTORY
DH_generate_key() and
DH_compute_key() first appeared in SSLeay 0.5.1 and
have been available since OpenBSD 2.4.