| =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 |
