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1#ifndef OPTIMIZED_CIPHER_H
2#define OPTIMIZED_CIPHER_H
3
4#include <stdint.h>
5#include <stdlib.h>
6#include <string.h>
7#include <stdbool.h>
8
9/**
10* Definition 1 (Cipher state). A cipher state of iClass s is an element of F 40/2
11* consisting of the following four components:
12* 1. the left register l = (l 0 . . . l 7 ) ∈ F 8/2 ;
13* 2. the right register r = (r 0 . . . r 7 ) ∈ F 8/2 ;
14* 3. the top register t = (t 0 . . . t 15 ) ∈ F 16/2 .
15* 4. the bottom register b = (b 0 . . . b 7 ) ∈ F 8/2 .
16**/
17typedef struct {
18 uint8_t l;
19 uint8_t r;
20 uint8_t b;
21 uint16_t t;
22} State;
23
24/** The reader MAC is MAC(key, CC * NR )
25 **/
26void opt_doReaderMAC(uint8_t *cc_nr_p, uint8_t *div_key_p, uint8_t mac[4]);
27/**
28 * The tag MAC is MAC(key, CC * NR * 32x0))
29 */
30void opt_doTagMAC(uint8_t *cc_p, const uint8_t *div_key_p, uint8_t mac[4]);
31
32/**
33 * The tag MAC can be divided (both can, but no point in dividing the reader mac) into
34 * two functions, since the first 8 bytes are known, we can pre-calculate the state
35 * reached after feeding CC to the cipher.
36 * @param cc_p
37 * @param div_key_p
38 * @return the cipher state
39 */
40State opt_doTagMAC_1(uint8_t *cc_p, const uint8_t *div_key_p);
41/**
42 * The second part of the tag MAC calculation, since the CC is already calculated into the state,
43 * this function is fed only the NR, and internally feeds the remaining 32 0-bits to generate the tag
44 * MAC response.
45 * @param _init - precalculated cipher state
46 * @param nr - the reader challenge
47 * @param mac - where to store the MAC
48 * @param div_key_p - the key to use
49 */
50void opt_doTagMAC_2(State _init, uint8_t* nr, uint8_t mac[4], const uint8_t* div_key_p);
51
52#endif // OPTIMIZED_CIPHER_H
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