| 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 |