#include <stdint.h>
#include <time.h>
-/**
-* Definition 1 (Cipher state). A cipher state of iClass s is an element of F 40/2
-* consisting of the following four components:
-* 1. the left register l = (l 0 . . . l 7 ) ∈ F 8/2 ;
-* 2. the right register r = (r 0 . . . r 7 ) ∈ F 8/2 ;
-* 3. the top register t = (t 0 . . . t 15 ) ∈ F 16/2 .
-* 4. the bottom register b = (b 0 . . . b 7 ) ∈ F 8/2 .
-**/
-typedef struct {
- uint8_t l;
- uint8_t r;
- uint8_t b;
- uint16_t t;
-} State;
-
#define opt_T(s) (0x1 & ((s->t >> 15) ^ (s->t >> 14)^ (s->t >> 10)^ (s->t >> 8)^ (s->t >> 5)^ (s->t >> 4)^ (s->t >> 1)^ s->t))
}
*/
-void opt_successor(uint8_t* k, State *s, bool y, State* successor)
+void opt_successor(const uint8_t* k, State *s, bool y, State* successor)
{
uint8_t Tt = 1 & opt_T(s);
}
-void opt_suc(uint8_t* k,State* s, uint8_t *in)
+void opt_suc(const uint8_t* k,State* s, uint8_t *in, uint8_t length, bool add32Zeroes)
{
State x2;
int i;
uint8_t head = 0;
- for(i =0 ; i < 12 ; i++)
+ for(i =0 ; i < length ; i++)
{
head = 1 & (in[i] >> 7);
opt_successor(k,s,head,&x2);
opt_successor(k,&x2,head,s);
}
-
+ //For tag MAC, an additional 32 zeroes
+ if(add32Zeroes)
+ for(i =0 ; i < 16 ; i++)
+ {
+ opt_successor(k,s,0,&x2);
+ opt_successor(k,&x2,0,s);
+ }
}
-void opt_output(uint8_t* k,State* s, uint8_t *buffer)
+void opt_output(const uint8_t* k,State* s, uint8_t *buffer)
{
uint8_t times = 0;
uint8_t bout = 0;
0xE012 // t
};
- opt_suc(k,&_init,input);
+ opt_suc(k,&_init,input,12, false);
//printf("\noutp ");
opt_output(k,&_init, out);
}
dest[i] = rev_byte(src[i]);
}
-void opt_doMAC(uint8_t *cc_nr_p, uint8_t *div_key_p, uint8_t mac[4])
+void opt_doReaderMAC(uint8_t *cc_nr_p, uint8_t *div_key_p, uint8_t mac[4])
{
- static uint8_t cc_nr[13];
- static uint8_t div_key[8];
+ static uint8_t cc_nr[12];
opt_reverse_arraybytecpy(cc_nr, cc_nr_p,12);
- memcpy(div_key,div_key_p,8);
uint8_t dest []= {0,0,0,0,0,0,0,0};
- opt_MAC(div_key,cc_nr, dest);
+ opt_MAC(div_key_p,cc_nr, dest);
+ //The output MAC must also be reversed
+ opt_reverse_arraybytecpy(mac, dest,4);
+ return;
+}
+void opt_doTagMAC(uint8_t *cc_p, const uint8_t *div_key_p, uint8_t mac[4])
+{
+ static uint8_t cc_nr[8+4+4];
+ opt_reverse_arraybytecpy(cc_nr, cc_p,12);
+ State _init = {
+ ((div_key_p[0] ^ 0x4c) + 0xEC) & 0xFF,// l
+ ((div_key_p[0] ^ 0x4c) + 0x21) & 0xFF,// r
+ 0x4c, // b
+ 0xE012 // t
+ };
+ opt_suc(div_key_p,&_init,cc_nr, 12,true);
+ uint8_t dest []= {0,0,0,0};
+ opt_output(div_key_p,&_init, dest);
+ //The output MAC must also be reversed
+ opt_reverse_arraybytecpy(mac, dest,4);
+ return;
+
+}
+/**
+ * The tag MAC can be divided (both can, but no point in dividing the reader mac) into
+ * two functions, since the first 8 bytes are known, we can pre-calculate the state
+ * reached after feeding CC to the cipher.
+ * @param cc_p
+ * @param div_key_p
+ * @return the cipher state
+ */
+State opt_doTagMAC_1(uint8_t *cc_p, const uint8_t *div_key_p)
+{
+ static uint8_t cc_nr[8];
+ opt_reverse_arraybytecpy(cc_nr, cc_p,8);
+ State _init = {
+ ((div_key_p[0] ^ 0x4c) + 0xEC) & 0xFF,// l
+ ((div_key_p[0] ^ 0x4c) + 0x21) & 0xFF,// r
+ 0x4c, // b
+ 0xE012 // t
+ };
+ opt_suc(div_key_p,&_init,cc_nr, 8,false);
+ return _init;
+}
+/**
+ * The second part of the tag MAC calculation, since the CC is already calculated into the state,
+ * this function is fed only the NR, and internally feeds the remaining 32 0-bits to generate the tag
+ * MAC response.
+ * @param _init - precalculated cipher state
+ * @param nr - the reader challenge
+ * @param mac - where to store the MAC
+ * @param div_key_p - the key to use
+ */
+void opt_doTagMAC_2(State _init, uint8_t* nr, uint8_t mac[4], const uint8_t* div_key_p)
+{
+ static uint8_t _nr [4];
+ opt_reverse_arraybytecpy(_nr, nr, 4);
+ opt_suc(div_key_p,&_init,_nr, 4, true);
+ //opt_suc(div_key_p,&_init,nr, 4, false);
+ uint8_t dest []= {0,0,0,0};
+ opt_output(div_key_p,&_init, dest);
//The output MAC must also be reversed
- opt_reverse_arraybytecpy(mac, dest,12);
+ opt_reverse_arraybytecpy(mac, dest,4);
return;
}