openssl/doc/crypto/DH_generate_key.pod
Richard Levitte b3c1d18d03 It makes more sense to refer to specific function manuals than the concept
manual when the specific function is refered to in the current manual text.
This correction was originally introduced in OpenBSD's tracking of OpenSSL.
2002-09-25 13:34:37 +00:00

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=pod
=head1 NAME
DH_generate_key, DH_compute_key - perform Diffie-Hellman key exchange
=head1 SYNOPSIS
#include <openssl/dh.h>
int DH_generate_key(DH *dh);
int DH_compute_key(unsigned char *key, BIGNUM *pub_key, DH *dh);
=head1 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 B<dh> to contain the shared parameters
B<dh-E<gt>p> and B<dh-E<gt>g>. It generates a random private DH value
unless B<dh-E<gt>priv_key> is already set, and computes the
corresponding public value B<dh-E<gt>pub_key>, which can then be
published.
DH_compute_key() computes the shared secret from the private DH value
in B<dh> and the other party's public value in B<pub_key> and stores
it in B<key>. B<key> must point to B<DH_size(dh)> bytes of memory.
=head1 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 L<ERR_get_error(3)|ERR_get_error(3)>.
=head1 SEE ALSO
L<dh(3)|dh(3)>, L<ERR_get_error(3)|ERR_get_error(3)>, L<rand(3)|rand(3)>, L<DH_size(3)|DH_size(3)>
=head1 HISTORY
DH_generate_key() and DH_compute_key() are available in all versions
of SSLeay and OpenSSL.
=cut