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	1	/*****************************************************************************
	2	* WARNING
	3	*
	4	* THIS CODE IS CREATED FOR EXPERIMENTATION AND EDUCATIONAL USE ONLY.
	5	*
	6	* USAGE OF THIS CODE IN OTHER WAYS MAY INFRINGE UPON THE INTELLECTUAL
	7	* PROPERTY OF OTHER PARTIES, SUCH AS INSIDE SECURE AND HID GLOBAL,
	8	* AND MAY EXPOSE YOU TO AN INFRINGEMENT ACTION FROM THOSE PARTIES.
	9	*
	10	* THIS CODE SHOULD NEVER BE USED TO INFRINGE PATENTS OR INTELLECTUAL PROPERTY RIGHTS.
	11	*
	12	*****************************************************************************
	13	*
	14	* This file is part of loclass. It is a reconstructon of the cipher engine
	15	* used in iClass, and RFID techology.
	16	*
	17	* The implementation is based on the work performed by
	18	* Flavio D. Garcia, Gerhard de Koning Gans, Roel Verdult and
	19	* Milosch Meriac in the paper "Dismantling IClass".
	20	*
	21	* Copyright (C) 2014 Martin Holst Swende
	22	*
	23	* This is free software: you can redistribute it and/or modify
	24	* it under the terms of the GNU General Public License version 2 as published
	25	* by the Free Software Foundation, or, at your option, any later version.
	26	*
	27	* This file is distributed in the hope that it will be useful,
	28	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	29	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	30	* GNU General Public License for more details.
	31	*
	32	* You should have received a copy of the GNU General Public License
	33	* along with loclass. If not, see <http://www.gnu.org/licenses/>.
	34	*
	35	*
	36	****************************************************************************/
	37
	38	#ifndef OPTIMIZED_CIPHER_H__
	39	#define OPTIMIZED_CIPHER_H__
	40
	41	#include <stdint.h>
	42
	43	/**
	44	* Definition 1 (Cipher state). A cipher state of iClass s is an element of F 40/2
	45	* consisting of the following four components:
	46	* 1. the left register l = (l 0 . . . l 7 ) ∈ F 8/2 ;
	47	* 2. the right register r = (r 0 . . . r 7 ) ∈ F 8/2 ;
	48	* 3. the top register t = (t 0 . . . t 15 ) ∈ F 16/2 .
	49	* 4. the bottom register b = (b 0 . . . b 7 ) ∈ F 8/2 .
	50	**/
	51	typedef struct {
	52	uint8_t l;
	53	uint8_t r;
	54	uint8_t b;
	55	uint16_t t;
	56	} State;
	57
	58	/** The reader MAC is MAC(key, CC * NR )
	59	**/
	60	void opt_doReaderMAC(uint8_t cc_nr_p, uint8_t div_key_p, uint8_t mac[4]);
	61
	62	/**
	63	* The tag MAC is MAC(key, CC * NR * 32x0))
	64	*/
	65	void opt_doTagMAC(uint8_t cc_p, const uint8_t div_key_p, uint8_t mac[4]);
	66
	67	/**
	68	* The tag MAC can be divided (both can, but no point in dividing the reader mac) into
	69	* two functions, since the first 8 bytes are known, we can pre-calculate the state
	70	* reached after feeding CC to the cipher.
	71	* @param cc_p
	72	* @param div_key_p
	73	* @return the cipher state
	74	*/
	75	State opt_doTagMAC_1(uint8_t cc_p, const uint8_t div_key_p);
	76
	77	/**
	78	* The second part of the tag MAC calculation, since the CC is already calculated into the state,
	79	* this function is fed only the NR, and internally feeds the remaining 32 0-bits to generate the tag
	80	* MAC response.
	81	* @param _init - precalculated cipher state
	82	* @param nr - the reader challenge
	83	* @param mac - where to store the MAC
	84	* @param div_key_p - the key to use
	85	*/
	86	void opt_doTagMAC_2(State _init, uint8_t nr, uint8_t mac[4], const uint8_t div_key_p);
	87
	88	#endif // OPTIMIZED_CIPHER_H__