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48 lines
1.6 KiB
C
48 lines
1.6 KiB
C
#ifndef OPTIMIZED_CIPHER_H
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#define OPTIMIZED_CIPHER_H
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#include <stdint.h>
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/**
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* Definition 1 (Cipher state). A cipher state of iClass s is an element of F 40/2
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* consisting of the following four components:
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* 1. the left register l = (l 0 . . . l 7 ) ∈ F 8/2 ;
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* 2. the right register r = (r 0 . . . r 7 ) ∈ F 8/2 ;
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* 3. the top register t = (t 0 . . . t 15 ) ∈ F 16/2 .
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* 4. the bottom register b = (b 0 . . . b 7 ) ∈ F 8/2 .
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**/
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typedef struct {
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uint8_t l;
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uint8_t r;
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uint8_t b;
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uint16_t t;
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} State;
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/** The reader MAC is MAC(key, CC * NR )
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**/
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void opt_doReaderMAC(uint8_t *cc_nr_p, uint8_t *div_key_p, uint8_t mac[4]);
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/**
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* The tag MAC is MAC(key, CC * NR * 32x0))
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*/
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void opt_doTagMAC(uint8_t *cc_p, const uint8_t *div_key_p, uint8_t mac[4]);
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/**
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* The tag MAC can be divided (both can, but no point in dividing the reader mac) into
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* two functions, since the first 8 bytes are known, we can pre-calculate the state
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* reached after feeding CC to the cipher.
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* @param cc_p
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* @param div_key_p
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* @return the cipher state
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*/
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State opt_doTagMAC_1(uint8_t *cc_p, const uint8_t *div_key_p);
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/**
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* The second part of the tag MAC calculation, since the CC is already calculated into the state,
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* this function is fed only the NR, and internally feeds the remaining 32 0-bits to generate the tag
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* MAC response.
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* @param _init - precalculated cipher state
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* @param nr - the reader challenge
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* @param mac - where to store the MAC
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* @param div_key_p - the key to use
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*/
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void opt_doTagMAC_2(State _init, uint8_t* nr, uint8_t mac[4], const uint8_t* div_key_p);
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#endif // OPTIMIZED_CIPHER_H
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