Implemented the correct way to calculate MAC from a tag, feeding it an extra 32 zeroe...

[proxmark3-svn] / armsrc / optimized_cipher.h

diff --git a/armsrc/optimized_cipher.h b/armsrc/optimized_cipher.h
index 0f4f0ec20be39ca094f12599ea26e47741128c3a..c10aea28bab4f2b75465173ee01ad8f38ecb19e1 100644 (file)
--- a/armsrc/optimized_cipher.h
+++ b/armsrc/optimized_cipher.h
@@ -1,5 +1,48 @@
 #ifndef OPTIMIZED_CIPHER_H
 #define OPTIMIZED_CIPHER_H
 #include <stdint.h>
-void opt_doMAC(uint8_t *cc_nr_p, uint8_t *div_key_p, uint8_t mac[4]);
+
+/**
+* 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;
+
+/** The reader MAC is MAC(key, CC * NR )
+ **/
+void opt_doReaderMAC(uint8_t *cc_nr_p, uint8_t *div_key_p, uint8_t mac[4]);
+/**
+ * The tag MAC is MAC(key, CC * NR * 32x0))
+ */
+void opt_doTagMAC(uint8_t *cc_p, const uint8_t *div_key_p, uint8_t mac[4]);
+
+/**
+ * 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);
+/**
+ * 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);
+
 #endif // OPTIMIZED_CIPHER_H