SilcBool silc_pkcs1_decode(SilcPkcs1BlockType bt,
                               const unsigned char *data,
                               SilcUInt32 data_len,
                               unsigned char *dest_data,
                               SilcUInt32 dest_data_size,
                               SilcUInt32 *dest_len);

    Decodes the PKCS#1 encoded block according to the block type `bt'.
    When verifying signatures the `bt' must be SILC_PKCS1_BT_PRV1 and
    when decrypting it must be SILC_PKCS1_BT_PUB.  This copies the
    decoded data into `dest_data' which is size of `dest_data_size'.  If
    the deocded block does not fit to `dest_data' this returns FALSE.
    Returns the decoded length into `dest_len'.