From: Martin Holst Swende <martin@swende.se>
Date: Sun, 1 Mar 2015 23:38:36 +0000 (+0100)
Subject: Implemented the correct way to calculate MAC from a tag, feeding it an extra 32 zeroe...
X-Git-Tag: v2.0.0-rc1~3
X-Git-Url: https://git.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/commitdiff_plain/61fe90736be4400f09fb5f56e2de48d11a0ae0a7
Implemented the correct way to calculate MAC from a tag, feeding it an extra 32 zeroes. Also divided it up into two parts, one of which can be precalculated by the device before the simulation begins
---
diff --git a/armsrc/iclass.c b/armsrc/iclass.c
index ca6d9a7e..f289d24e 100644
--- a/armsrc/iclass.c
+++ b/armsrc/iclass.c
@@ -1053,6 +1053,8 @@ int doIClassSimulation( int simulationMode, uint8_t *reader_mac_buf)
// free eventually allocated BigBuf memory
BigBuf_free_keep_EM();
+ State cipher_state;
+// State cipher_state_reserve;
uint8_t *csn = BigBuf_get_EM_addr();
uint8_t *emulator = csn;
uint8_t sof_data[] = { 0x0F} ;
@@ -1069,12 +1071,18 @@ int doIClassSimulation( int simulationMode, uint8_t *reader_mac_buf)
ComputeCrc14443(CRC_ICLASS, anticoll_data, 8, &anticoll_data[8], &anticoll_data[9]);
ComputeCrc14443(CRC_ICLASS, csn_data, 8, &csn_data[8], &csn_data[9]);
+ //The diversified key should be stored on block 3
+ uint8_t diversified_key[8] = { 0 };
+ //Get the diversified key from emulator memory
+ memcpy(diversified_key, emulator+(8*3),8);
// e-Purse
uint8_t card_challenge_data[8] = { 0x00 };
if(simulationMode == MODE_FULLSIM)
{
//Card challenge, a.k.a e-purse is on block 2
memcpy(card_challenge_data,emulator + (8 * 2) , 8);
+ //Precalculate the cipher state, feeding it the CC
+ opt_doTagMAC_1(card_challenge_data,diversified_key);
}
int exitLoop = 0;
@@ -1200,21 +1208,10 @@ int doIClassSimulation( int simulationMode, uint8_t *reader_mac_buf)
} else if(receivedCmd[0] == ICLASS_CMD_CHECK) {
// Reader random and reader MAC!!!
if(simulationMode == MODE_FULLSIM)
- { //This is what we must do..
- //Reader just sent us NR and MAC(k,cc * nr)
- //The diversified key should be stored on block 3
- //However, from a typical dump, the key will not be there
- uint8_t diversified_key[8] = { 0 };
-
- //Get the diversified key from emulator memory
- memcpy(diversified_key, emulator+(8*3),8);
- uint8_t ccnr[12] = { 0 };
- //Put our cc there (block 2)
- memcpy(ccnr, emulator + (8 * 2), 8);
- //Put nr there
- memcpy(ccnr+8, receivedCmd+1,4);
- //Now, calc MAC
- opt_doMAC(ccnr,diversified_key, data_generic_trace);
+ {
+ //NR, from reader, is in receivedCmd +1
+ opt_doTagMAC_2(cipher_state,receivedCmd+1,data_generic_trace,diversified_key);
+
trace_data = data_generic_trace;
trace_data_size = 4;
CodeIClassTagAnswer(trace_data , trace_data_size);
diff --git a/armsrc/optimized_cipher.c b/armsrc/optimized_cipher.c
index 067e9022..444b93d0 100644
--- a/armsrc/optimized_cipher.c
+++ b/armsrc/optimized_cipher.c
@@ -68,21 +68,6 @@
#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 ) â F 8/2 ;
-* 2. the right register r = (r 0 . . . r 7 ) â F 8/2 ;
-* 3. the top register t = (t 0 . . . t 15 ) â F 16/2 .
-* 4. the bottom register b = (b 0 . . . b 7 ) â 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))
@@ -118,7 +103,7 @@ uint8_t xopt__select(bool x, bool y, uint8_t r)
}
*/
-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);
@@ -134,12 +119,12 @@ void opt_successor(uint8_t* k, State *s, bool y, State* successor)
}
-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);
@@ -166,10 +151,16 @@ void opt_suc(uint8_t* k,State* s, uint8_t *in)
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;
@@ -207,7 +198,7 @@ void opt_MAC(uint8_t* k, uint8_t* input, uint8_t* out)
0xE012 // t
};
- opt_suc(k,&_init,input);
+ opt_suc(k,&_init,input,12, false);
//printf("\noutp ");
opt_output(k,&_init, out);
}
@@ -224,16 +215,74 @@ void opt_reverse_arraybytecpy(uint8_t* dest, uint8_t *src, size_t len)
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;
}
diff --git a/armsrc/optimized_cipher.h b/armsrc/optimized_cipher.h
index 0f4f0ec2..c10aea28 100644
--- 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 ) â F 8/2 ;
+* 2. the right register r = (r 0 . . . r 7 ) â F 8/2 ;
+* 3. the top register t = (t 0 . . . t 15 ) â F 16/2 .
+* 4. the bottom register b = (b 0 . . . b 7 ) â 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