fix changelog conflict

[proxmark3-svn] / armsrc / iso14443a.c

diff --git a/armsrc/iso14443a.c b/armsrc/iso14443a.c
index f81a1a99a6a44dff93c6ed1e52f39a3d72bbde34..0431876eca41eb756342de78d8a3e58a75711f78 100644 (file)
--- a/armsrc/iso14443a.c
+++ b/armsrc/iso14443a.c
@@ -2016,6 +2016,7 @@ void ReaderMifare(bool first_try)
        byte_t par_list[8] = {0x00};
        byte_t ks_list[8] = {0x00};
 
+       #define PRNG_SEQUENCE_LENGTH  (1 << 16);
        static uint32_t sync_time;
        static uint32_t sync_cycles;
        int catch_up_cycles = 0;
@@ -2026,7 +2027,7 @@ void ReaderMifare(bool first_try)
        if (first_try) { 
                mf_nr_ar3 = 0;
                sync_time = GetCountSspClk() & 0xfffffff8;
-               sync_cycles = 65536;                                                                    // theory: Mifare Classic's random generator repeats every 2^16 cycles (and so do the nonces).
+               sync_cycles = PRNG_SEQUENCE_LENGTH;                                                     // theory: Mifare Classic's random generator repeats every 2^16 cycles (and so do the tag nonces).
                nt_attacked = 0;
                nt = 0;
                par[0] = 0;
@@ -2043,8 +2044,12 @@ void ReaderMifare(bool first_try)
        LED_C_OFF();
        
 
-       #define DARKSIDE_MAX_TRIES      32              // number of tries to sync on PRNG cycle. Then give up.
-       uint16_t unsuccessfull_tries = 0;
+       #define MAX_UNEXPECTED_RANDOM   4               // maximum number of unexpected (i.e. real) random numbers when trying to sync. Then give up.
+       #define MAX_SYNC_TRIES                  16
+       uint16_t unexpected_random = 0;
+       uint16_t sync_tries = 0;
+       int16_t debug_info_nr = -1;
+       uint32_t debug_info[MAX_SYNC_TRIES];
        
        for(uint16_t i = 0; TRUE; i++) {
                
@@ -2062,16 +2067,20 @@ void ReaderMifare(bool first_try)
                        continue;
                }
 
-               sync_time = (sync_time & 0xfffffff8) + sync_cycles + catch_up_cycles;
-               catch_up_cycles = 0;
+               if (debug_info_nr == -1) {
+                       sync_time = (sync_time & 0xfffffff8) + sync_cycles + catch_up_cycles;
+                       catch_up_cycles = 0;
 
-               // if we missed the sync time already, advance to the next nonce repeat
-               while(GetCountSspClk() > sync_time) {
-                       sync_time = (sync_time & 0xfffffff8) + sync_cycles;
-               }
+                       // if we missed the sync time already, advance to the next nonce repeat
+                       while(GetCountSspClk() > sync_time) {
+                               sync_time = (sync_time & 0xfffffff8) + sync_cycles;
+                       }
 
-               // Transmit MIFARE_CLASSIC_AUTH at synctime. Should result in returning the same tag nonce (== nt_attacked) 
-               ReaderTransmit(mf_auth, sizeof(mf_auth), &sync_time);
+                       // Transmit MIFARE_CLASSIC_AUTH at synctime. Should result in returning the same tag nonce (== nt_attacked) 
+                       ReaderTransmit(mf_auth, sizeof(mf_auth), &sync_time);
+               } else {
+                       ReaderTransmit(mf_auth, sizeof(mf_auth), NULL);
+               }                       
 
                // Receive the (4 Byte) "random" nonce
                if (!ReaderReceive(receivedAnswer, receivedAnswerPar)) {
@@ -2089,19 +2098,32 @@ void ReaderMifare(bool first_try)
                        int nt_distance = dist_nt(previous_nt, nt);
                        if (nt_distance == 0) {
                                nt_attacked = nt;
-                       }
-                       else {
+                       } else {
                                if (nt_distance == -99999) { // invalid nonce received
-                                       unsuccessfull_tries++;
-                                       if (!nt_attacked && unsuccessfull_tries > DARKSIDE_MAX_TRIES) {
+                                       unexpected_random++;
+                                       if (!nt_attacked && unexpected_random > MAX_UNEXPECTED_RANDOM) {
                                                isOK = -3;              // Card has an unpredictable PRNG. Give up      
                                                break;
                                        } else {
                                                continue;               // continue trying...
                                        }
                                }
+                               if (++sync_tries > MAX_SYNC_TRIES) {
+                                       if (sync_tries > 2 * MAX_SYNC_TRIES) {
+                                               isOK = -4;                      // Card's PRNG runs at an unexpected frequency or resets unexpectedly
+                                               break;
+                                       } else {                                // continue for a while, just to collect some debug info
+                                               debug_info[++debug_info_nr] = nt_distance;
+                                               continue;
+                                       }
+                               }
                                sync_cycles = (sync_cycles - nt_distance);
-                               if (MF_DBGLEVEL >= 3) Dbprintf("calibrating in cycle %d. nt_distance=%d, Sync_cycles: %d\n", i, nt_distance, sync_cycles);
+                               if (sync_cycles <= 0) {
+                                       sync_cycles += PRNG_SEQUENCE_LENGTH;
+                               }
+                               if (MF_DBGLEVEL >= 3) {
+                                       Dbprintf("calibrating in cycle %d. nt_distance=%d, Sync_cycles: %d\n", i, nt_distance, sync_cycles);
+                               }
                                continue;
                        }
                }
@@ -2172,6 +2194,14 @@ void ReaderMifare(bool first_try)
 
 
        mf_nr_ar[3] &= 0x1F;
+
+       if (isOK == -4) {
+               if (MF_DBGLEVEL >= 3) {
+                       for(uint16_t i = 0; i < MAX_SYNC_TRIES; i++) {
+                               Dbprintf("collected debug info[%d] = %d\n", i, debug_info[i]);
+                       }
+               }
+       }
        
        byte_t buf[28];
        memcpy(buf + 0,  uid, 4);