 BN_CTX *ctx, BN_GENCB *cb);

 int BN_GENCB_call(BN_GENCB *cb, int a, int b);

 BN_GENCB *BN_GENCB_new(void);

 void BN_GENCB_free(BN_GENCB *cb);

 void BN_GENCB_set_old(BN_GENCB *gencb,
                       void (*callback)(int, int, void *), void *cb_arg);

 void BN_GENCB_set(BN_GENCB *gencb,
                   int (*callback)(int, int, BN_GENCB *), void *cb_arg);

 void *BN_GENCB_get_arg(BN_GENCB *cb);</code></pre>

<p>The following functions have been deprecated since OpenSSL 0.9.8, and can be hidden 