NAME    [Toc]    [Back]

       DH_generate_key, DH_compute_key - perform Diffie-Hellman
       key exchange

LIBRARY    [Toc]    [Back]

       libcrypto, -lcrypto

SYNOPSIS    [Toc]    [Back]

        #include <openssl/dh.h>

        int DH_generate_key(DH *dh);

        int DH_compute_key(unsigned char *key, BIGNUM *pub_key, DH *dh);

DESCRIPTION    [Toc]    [Back]

       DH_generate_key() performs the first step of a DiffieHellman
 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    [Toc]    [Back]

       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    [Toc]    [Back]

       openssl_dh(3), openssl_err(3), openssl_rand(3), DH_size(3)

HISTORY    [Toc]    [Back]

       DH_generate_key() and DH_compute_key() are available in
       all versions of SSLeay and OpenSSL.



2000-07-22                    0.9.6g           DH_generate_key(3)