SilcSKEStatus silc_ske_process_key_material(SilcSKE ske,
                                                SilcUInt32 req_iv_len,
                                                SilcUInt32 req_enc_key_len,
                                                SilcUInt32 req_hmac_key_len,
                                                SilcSKEKeyMaterial *key);

    This function is used by the application to process the key material
    negotiated with the SKE session, to actually produce the keys that
    is to be used in SILC protocol. The key processing is defined by the
    protocol. The `req_iv_len', `req_enc_key_len' and `req_hmac_key_len'
    are the request IV length, requested encryption/decrypt key length,
    and requested HMAC key length, respectively, and  they cannot be
    zero (0). They tell the function how long the keys should be, and
    it will produce the requested length keys for the application.
    The key material is returned in to the `key', which the caller must
    free.