Merge pull request #209 from micolous/14a-random-nonce

Adds random nonce (r) option to `hf mf sim`.

armsrc/iso14443a.c

@@ -2329,6 +2329,7 @@ typedef struct {
   * FLAG_7B_UID_IN_DATA - means that there is a 7-byte UID in the data-section, we're expected to use that
   * FLAG_10B_UID_IN_DATA	- use 10-byte UID in the data-section not finished
   *	FLAG_NR_AR_ATTACK  - means we should collect NR_AR responses for bruteforcing later
+  * FLAG_RANDOM_NONCE - means we should generate some pseudo-random nonce data (only allows moebius attack)
   *@param exitAfterNReads, exit simulation after n blocks have been read, 0 is infinite ...
   * (unless reader attack mode enabled then it runs util it gets enough nonces to recover all keys attmpted)
   */
@@ -2387,7 +2388,12 @@ void Mifare1ksim(uint8_t flags, uint8_t exitAfterNReads, uint8_t arg2, uint8_t *
 	uint8_t	mM = 0; //moebius_modifier for collection storage
 
 	// Authenticate response - nonce
-	uint32_t nonce = bytes_to_num(rAUTH_NT, 4);
+	uint32_t nonce;
+	if (flags & FLAG_RANDOM_NONCE) {
+		nonce = prand();
+	} else {
+		nonce = bytes_to_num(rAUTH_NT, 4);
+	}
 	
 	//-- Determine the UID
 	// Can be set from emulator memory, incoming data
@@ -2535,6 +2541,9 @@ void Mifare1ksim(uint8_t flags, uint8_t exitAfterNReads, uint8_t arg2, uint8_t *
 			LED_C_OFF();
 			crypto1_destroy(pcs);
 			cardAUTHKEY = 0xff;
+			if (flags & FLAG_RANDOM_NONCE) {
+				nonce = prand();
+			}
 			continue;
 		}
 		
@@ -2656,7 +2665,11 @@ void Mifare1ksim(uint8_t flags, uint8_t exitAfterNReads, uint8_t arg2, uint8_t *
 												// switch to moebius collection
 												gettingMoebius = true;
 												mM = ATTACK_KEY_COUNT;
-												nonce = nonce*7;
+												if (flags & FLAG_RANDOM_NONCE) {
+													nonce = prand();
+												} else {
+													nonce = nonce*7;
+												}
 												break;
 											}
 										} else {

armsrc/util.c

@@ -431,3 +431,19 @@ uint32_t RAMFUNC GetCountSspClk(){
 	}
 }
 
+static uint64_t next_random = 1;
+
+/* Generates a (non-cryptographically secure) 32-bit random number.
+ *
+ * We don't have an implementation of the "rand" function or a clock to seed it
+ * with, so we just call GetTickCount the first time to seed ourselves.
+ */
+uint32_t prand() {
+	if (next_random == 1) {
+		next_random = GetTickCount();
+	}
+
+	next_random = next_random * 6364136223846793005 + 1;
+	return (uint32_t)(next_random >> 32) % 0xffffffff;
+}
+

armsrc/util.h

@@ -54,4 +54,6 @@ uint32_t RAMFUNC GetDeltaCountUS();
 void StartCountSspClk();
 uint32_t RAMFUNC GetCountSspClk();
 
+uint32_t prand();
+
 #endif

client/cmdhfmf.c

@@ -1016,7 +1016,7 @@ int CmdHF14AMfChk(const char *Cmd)
 	return 0;
 }
 
-void readerAttack(nonces_t ar_resp[], bool setEmulatorMem) {
+void readerAttack(nonces_t ar_resp[], bool setEmulatorMem, bool doStandardAttack) {
 	#define ATTACK_KEY_COUNT 8 // keep same as define in iso14443a.c -> Mifare1ksim()
 	uint64_t key = 0;
 	typedef struct {
@@ -1034,7 +1034,7 @@ void readerAttack(nonces_t ar_resp[], bool setEmulatorMem) {
 	for (uint8_t i = 0; i<ATTACK_KEY_COUNT; i++) {
 		if (ar_resp[i].ar2 > 0) {
 			//PrintAndLog("DEBUG: Trying sector %d, cuid %08x, nt %08x, ar %08x, nr %08x, ar2 %08x, nr2 %08x",ar_resp[i].sector, ar_resp[i].cuid,ar_resp[i].nonce,ar_resp[i].ar,ar_resp[i].nr,ar_resp[i].ar2,ar_resp[i].nr2);
-			if (mfkey32(ar_resp[i], &key)) {
+			if (doStandardAttack && mfkey32(ar_resp[i], &key)) {
 				PrintAndLog("  Found Key%s for sector %02d: [%04x%08x]", (ar_resp[i].keytype) ? "B" : "A", ar_resp[i].sector, (uint32_t) (key>>32), (uint32_t) (key &0xFFFFFFFF));
 
 				for (uint8_t ii = 0; ii<ATTACK_KEY_COUNT; ii++) {
@@ -1054,6 +1054,34 @@ void readerAttack(nonces_t ar_resp[], bool setEmulatorMem) {
 						}
 					}
 				}
+			} else if (tryMfk32_moebius(ar_resp[i+ATTACK_KEY_COUNT], &key)) {
+				uint8_t sectorNum = ar_resp[i+ATTACK_KEY_COUNT].sector;
+				uint8_t keyType = ar_resp[i+ATTACK_KEY_COUNT].keytype;
+
+				PrintAndLog("M-Found Key%s for sector %02d: [%012"llx"]"
+					, keyType ? "B" : "A"
+					, sectorNum
+					, key
+				);
+
+				for (uint8_t ii = 0; ii<ATTACK_KEY_COUNT; ii++) {
+					if (key_cnt[ii]==0 || stSector[ii]==sectorNum) {
+						if (keyType==0) {
+							//keyA
+							sector_trailer[ii].keyA = key;
+							stSector[ii] = sectorNum;
+							key_cnt[ii]++;
+							break;
+						} else {
+							//keyB
+							sector_trailer[ii].keyB = key;
+							stSector[ii] = sectorNum;
+							key_cnt[ii]++;
+							break;
+						}
+					}
+				}
+				continue;
 			}
 		}
 	}
@@ -1100,6 +1128,7 @@ int usage_hf14_mf1ksim(void) {
 	PrintAndLog("      x    (Optional) Crack, performs the 'reader attack', nr/ar attack against a legitimate reader, fishes out the key(s)");
 	PrintAndLog("      e    (Optional) set keys found from 'reader attack' to emulator memory (implies x and i)");
 	PrintAndLog("      f    (Optional) get UIDs to use for 'reader attack' from file 'f <filename.txt>' (implies x and i)");
+	PrintAndLog("      r    (Optional) Generate random nonces instead of sequential nonces. Standard reader attack won't work with this option, only moebius attack works.");
 	PrintAndLog("samples:");
 	PrintAndLog("           hf mf sim u 0a0a0a0a");
 	PrintAndLog("           hf mf sim u 11223344556677");
@@ -1164,6 +1193,11 @@ int CmdHF14AMf1kSim(const char *Cmd) {
 			exitAfterNReads = param_get8(Cmd, pnr+1);
 			cmdp += 2;
 			break;
+		case 'r':
+		case 'R':
+			flags |= FLAG_RANDOM_NONCE;
+			cmdp++;
+			break;
 		case 'u':
 		case 'U':
 			param_gethex_ex(Cmd, cmdp+1, uid, &uidlen);
@@ -1246,7 +1280,8 @@ int CmdHF14AMf1kSim(const char *Cmd) {
 			//got a response
 			nonces_t ar_resp[ATTACK_KEY_COUNT*2];
 			memcpy(ar_resp, resp.d.asBytes, sizeof(ar_resp));
-			readerAttack(ar_resp, setEmulatorMem);
+			// We can skip the standard attack if we have RANDOM_NONCE set.
+			readerAttack(ar_resp, setEmulatorMem, !(flags & FLAG_RANDOM_NONCE));
 			if ((bool)resp.arg[1]) {
 				PrintAndLog("Device button pressed - quitting");
 				fclose(f);
@@ -1278,7 +1313,8 @@ int CmdHF14AMf1kSim(const char *Cmd) {
 			if (flags & FLAG_NR_AR_ATTACK) {
 				nonces_t ar_resp[ATTACK_KEY_COUNT*2];
 				memcpy(ar_resp, resp.d.asBytes, sizeof(ar_resp));
-				readerAttack(ar_resp, setEmulatorMem);
+				// We can skip the standard attack if we have RANDOM_NONCE set.
+				readerAttack(ar_resp, setEmulatorMem, !(flags & FLAG_RANDOM_NONCE));
 			}
 		}
 	}

include/usb_cmd.h

@@ -217,6 +217,7 @@ typedef struct{
 #define FLAG_7B_UID_IN_DATA   0x04
 #define FLAG_10B_UID_IN_DATA  0x08
 #define FLAG_NR_AR_ATTACK     0x10
+#define FLAG_RANDOM_NONCE     0x20
 
 
 //Iclass reader flags