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	1	#ifndef OPTIMIZED_CIPHER_H
	2	#define OPTIMIZED_CIPHER_H
	3	#include <stdint.h>
	4
	5	/**
	6	* Definition 1 (Cipher state). A cipher state of iClass s is an element of F 40/2
	7	* consisting of the following four components:
	8	* 1. the left register l = (l 0 . . . l 7 ) ∈ F 8/2 ;
	9	* 2. the right register r = (r 0 . . . r 7 ) ∈ F 8/2 ;
	10	* 3. the top register t = (t 0 . . . t 15 ) ∈ F 16/2 .
	11	* 4. the bottom register b = (b 0 . . . b 7 ) ∈ F 8/2 .
	12	**/
	13	typedef struct {
	14	uint8_t l;
	15	uint8_t r;
	16	uint8_t b;
	17	uint16_t t;
	18	} State;
	19
	20	/** The reader MAC is MAC(key, CC * NR )
	21	**/
	22	void opt_doReaderMAC(uint8_t cc_nr_p, uint8_t div_key_p, uint8_t mac[4]);
	23	/**
	24	* The tag MAC is MAC(key, CC * NR * 32x0))
	25	*/
	26	void opt_doTagMAC(uint8_t cc_p, const uint8_t div_key_p, uint8_t mac[4]);
	27
	28	/**
	29	* The tag MAC can be divided (both can, but no point in dividing the reader mac) into
	30	* two functions, since the first 8 bytes are known, we can pre-calculate the state
	31	* reached after feeding CC to the cipher.
	32	* @param cc_p
	33	* @param div_key_p
	34	* @return the cipher state
	35	*/
	36	State opt_doTagMAC_1(uint8_t cc_p, const uint8_t div_key_p);
	37	/**
	38	* The second part of the tag MAC calculation, since the CC is already calculated into the state,
	39	* this function is fed only the NR, and internally feeds the remaining 32 0-bits to generate the tag
	40	* MAC response.
	41	* @param _init - precalculated cipher state
	42	* @param nr - the reader challenge
	43	* @param mac - where to store the MAC
	44	* @param div_key_p - the key to use
	45	*/
	46	void opt_doTagMAC_2(State _init, uint8_t* nr, uint8_t mac[4], const uint8_t* div_key_p);
	47
	48	#endif // OPTIMIZED_CIPHER_H