DH_GENERATE_KEY(3)           OpenSSL           DH_GENERATE_KEY(3)


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.














OpenBSD 4.6                 2000-04-04                          1