DH_generate_key(3)

     DH_generate_key(3)     0.9.6h (2002-09-25)     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.

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