Implemented VB6 rng for iclass lookup elite key search

Ported @bettse work from the Flipper Zero Picopass repository to use the lookup function with the VB6 rng

CHANGELOG.md

@@ -10,6 +10,7 @@ This project uses the changelog in accordance with [keepchangelog](http://keepac
 - Added `pm3_tears_for_fears.py` - a ISO14443b tear off script by Pierre Granier
 - Added new t55xx password (002BCFCF) sniffed from cheap cloner (@davidbeauchamp)
 - Fixed 'hf 14b sim' - now works (@michi-jung)
+- Added VB6 Rng for iclass elite keys lookup by porting @bettse work in the Flipper Zero Picopass App (@antiklesys)
 
 ## [Aurora.4.18589][2024-05-28]
 - Fixed the pm3 regressiontests for Hitag2Crack (@iceman1001)

client/src/cmdhficlass.c

@@ -3774,29 +3774,84 @@ out:
 
 // this method tries to identify in which configuration mode a iCLASS / iCLASS SE reader is in.
 // Standard or Elite / HighSecurity mode.  It uses a default key dictionary list in order to work.
+#define INITIAL_SEED 0x429080 // VB6 KDF Seed Value
+
+// Functions for generating keys using RNG
+uint32_t seed = INITIAL_SEED;
+uint8_t key_state[8];
+bool prepared = false;
+
+void picopass_elite_reset(void) {
+    memset(key_state, 0, sizeof(key_state));
+    seed = INITIAL_SEED;
+    prepared = false;
+}
+
+uint32_t picopass_elite_lcg(void) {
+    uint32_t mod = 0x1000000; // 2^24
+    uint32_t a = 0xFD43FD;
+    uint32_t c = 0xC39EC3;
+
+    return (a * seed + c) % mod;
+}
+
+uint32_t picopass_elite_rng(void) {
+    seed = picopass_elite_lcg();
+    return seed;
+}
+
+uint8_t picopass_elite_nextByte(void) {
+    return (picopass_elite_rng() >> 16) & 0xFF;
+}
+
+void picopass_elite_nextKey(uint8_t* key) {
+    if(prepared) {
+        for(size_t i = 0; i < 7; i++) {
+            key_state[i] = key_state[i + 1];
+        }
+        key_state[7] = picopass_elite_nextByte();
+    } else {
+        for(size_t i = 0; i < 8; i++) {
+            key_state[i] = picopass_elite_nextByte();
+        }
+        prepared = true;
+    }
+    memcpy(key, key_state, 8);
+}
+
 static int CmdHFiClassLookUp(const char *Cmd) {
     CLIParserContext *ctx;
     CLIParserInit(&ctx, "hf iclass lookup",
                   "This command take sniffed trace data and try to recovery a iCLASS Standard or iCLASS Elite key.",
                   "hf iclass lookup --csn 9655a400f8ff12e0 --epurse f0ffffffffffffff --macs 0000000089cb984b -f iclass_default_keys.dic\n"
-                  "hf iclass lookup --csn 9655a400f8ff12e0 --epurse f0ffffffffffffff --macs 0000000089cb984b -f iclass_default_keys.dic --elite"
+                  "hf iclass lookup --csn 9655a400f8ff12e0 --epurse f0ffffffffffffff --macs 0000000089cb984b -f iclass_default_keys.dic --elite\n"
+                  "hf iclass lookup --csn 9655a400f8ff12e0 --epurse f0ffffffffffffff --macs 0000000089cb984b --vb6rng"
                  );
 
     void *argtable[] = {
         arg_param_begin,
-        arg_str1("f", "file", "<fn>", "Dictionary file with default iclass keys"),
+        arg_str0("f", "file", "<fn>", "Dictionary file with default iclass keys"),
         arg_str1(NULL, "csn", "<hex>", "Specify CSN as 8 hex bytes"),
         arg_str1(NULL, "epurse", "<hex>", "Specify ePurse as 8 hex bytes"),
         arg_str1(NULL, "macs", "<hex>", "MACs"),
         arg_lit0(NULL, "elite", "Elite computations applied to key"),
         arg_lit0(NULL, "raw", "no computations applied to key"),
+        arg_lit0(NULL, "vb6rng", "use the VB6 rng for elite keys instead of a dictionary file"),
         arg_param_end
     };
     CLIExecWithReturn(ctx, Cmd, argtable, false);
 
+    bool use_vb6kdf = arg_get_lit(ctx, 7);
     int fnlen = 0;
     char filename[FILE_PATH_SIZE] = {0};
-    CLIParamStrToBuf(arg_get_str(ctx, 1), (uint8_t *)filename, FILE_PATH_SIZE, &fnlen);
+
+    bool use_elite = arg_get_lit(ctx, 5);
+    bool use_raw = arg_get_lit(ctx, 6);
+    if(use_vb6kdf){
+        use_elite = true;
+    }else{
+        CLIParamStrToBuf(arg_get_str(ctx, 1), (uint8_t *)filename, FILE_PATH_SIZE, &fnlen);
+    }
 
     int csn_len = 0;
     uint8_t csn[8] = {0};
@@ -3834,15 +3889,12 @@ static int CmdHFiClassLookUp(const char *Cmd) {
         }
     }
 
-    bool use_elite = arg_get_lit(ctx, 5);
-    bool use_raw = arg_get_lit(ctx, 6);
-
     CLIParserFree(ctx);
 
     uint8_t CCNR[12];
     uint8_t MAC_TAG[4] = { 0, 0, 0, 0 };
 
-    // stupid copy.. CCNR is a combo of epurse and reader nonce
+    // Stupid copy.. CCNR is a combo of epurse and reader nonce
     memcpy(CCNR, epurse, 8);
     memcpy(CCNR + 8, macs, 4);
     memcpy(MAC_TAG, macs + 4, 4);
@@ -3853,20 +3905,34 @@ static int CmdHFiClassLookUp(const char *Cmd) {
     PrintAndLogEx(SUCCESS, "   CCNR: " _GREEN_("%s"), sprint_hex(CCNR, sizeof(CCNR)));
     PrintAndLogEx(SUCCESS, "TAG MAC: %s", sprint_hex(MAC_TAG, sizeof(MAC_TAG)));
 
-    // run time
+    // Run time
     uint64_t t1 = msclock();
 
     uint8_t *keyBlock = NULL;
     uint32_t keycount = 0;
 
-    // load keys
-    int res = loadFileDICTIONARY_safe(filename, (void **)&keyBlock, 8, &keycount);
-    if (res != PM3_SUCCESS || keycount == 0) {
-        free(keyBlock);
-        return res;
+    if (!use_vb6kdf) {
+        // Load keys
+        int res = loadFileDICTIONARY_safe(filename, (void **)&keyBlock, 8, &keycount);
+        if (res != PM3_SUCCESS || keycount == 0) {
+            free(keyBlock);
+            return res;
+        }
+    } else {
+        // Generate 5000 keys using VB6 KDF
+        keycount = 5000;
+        keyBlock = malloc(keycount * 8);
+        if (!keyBlock) {
+            return PM3_EMALLOC;
+        }
+
+        picopass_elite_reset();
+        for (uint32_t i = 0; i < keycount; i++) {
+            picopass_elite_nextKey(keyBlock + (i * 8));
+        }
     }
 
-    //iclass_prekey_t
+    // Iclass_prekey_t
     iclass_prekey_t *prekey = calloc(keycount, sizeof(iclass_prekey_t));
     if (!prekey) {
         free(keyBlock);
@@ -3883,7 +3949,7 @@ static int CmdHFiClassLookUp(const char *Cmd) {
 
     PrintAndLogEx(INFO, "Sorting...");
 
-    // sort mac list.
+    // Sort mac list
     qsort(prekey, keycount, sizeof(iclass_prekey_t), cmp_uint32);
 
     PrintAndLogEx(SUCCESS, "Searching for " _YELLOW_("%s") " key...", "DEBIT");
@@ -3891,7 +3957,7 @@ static int CmdHFiClassLookUp(const char *Cmd) {
     iclass_prekey_t lookup;
     memcpy(lookup.mac, MAC_TAG, 4);
 
-    // binsearch
+    // Binsearch
     item = (iclass_prekey_t *) bsearch(&lookup, prekey, keycount, sizeof(iclass_prekey_t), cmp_uint32);
 
     if (item != NULL) {
@@ -3900,7 +3966,7 @@ static int CmdHFiClassLookUp(const char *Cmd) {
     }
 
     t1 = msclock() - t1;
-    PrintAndLogEx(SUCCESS, "time in iclass lookup " _YELLOW_("%.3f") " seconds", (float)t1 / 1000.0);
+    PrintAndLogEx(SUCCESS, "Time in iclass lookup " _YELLOW_("%.3f") " seconds", (float)t1 / 1000.0);
 
     free(prekey);
     free(keyBlock);

client/src/cmdhficlass.h

@@ -36,4 +36,10 @@ void PrintPreCalc(iclass_prekey_t *list, uint32_t itemcnt);
 
 uint8_t get_pagemap(const picopass_hdr_t *hdr);
 bool check_known_default(uint8_t *csn, uint8_t *epurse, uint8_t *rmac, uint8_t *tmac, uint8_t *key);
+
+void picopass_elite_nextKey(uint8_t* key);
+void picopass_elite_reset(void);
+uint32_t picopass_elite_rng(void);
+uint32_t picopass_elite_lcg(void);
+uint8_t picopass_elite_nextByte(void);
 #endif