+int compar_intA(const void * a, const void * b) {
+       if (*(int64_t*)b == *(int64_t*)a) return 0;
+       if (*(int64_t*)b > *(int64_t*)a) return 1;
+       return -1;
+}
+
+// call when PAR == 0,  special attack?  It seems to need two calls.  with same uid, block, keytype
+int nonce2key_ex(uint8_t blockno, uint8_t keytype, uint32_t uid, uint32_t nt, uint32_t nr, uint64_t ks_info, uint64_t * key) {
+
+       struct Crypto1State *state;
+       uint32_t i, pos, key_count;
+       uint8_t ks3x[8];
+       uint64_t key_recovered;
+       int64_t *state_s;
+       static uint8_t last_blockno;
+       static uint8_t last_keytype;
+       static uint32_t last_uid;
+       static int64_t *last_keylist;
+  
+       if (last_uid != uid &&
+               last_blockno != blockno &&
+               last_keytype != keytype &&
+               last_keylist != NULL)
+       {
+               free(last_keylist);
+               last_keylist = NULL;
+       }
+       last_uid = uid;
+       last_blockno = blockno;
+       last_keytype = keytype;
+
+       // Reset the last three significant bits of the reader nonce
+       nr &= 0xffffff1f;
+ 
+       // split keystream into array
+       for (pos=0; pos<8; pos++) {
+               ks3x[7-pos] = (ks_info >> (pos*8)) & 0x0f;
+       }
+ 
+       // find possible states for this keystream
+       state = lfsr_common_prefix_ex(nr, ks3x);
+
+       if (!state) {
+               PrintAndLog("Failed getting states");
+               return 1;
+       }
+       
+       state_s = (int64_t*)state;
+       
+       uint32_t xored = uid ^ nt;
+       
+       for (i = 0; (state) && ((state + i)->odd != -1); i++) {
+               lfsr_rollback_word(state + i, xored, 0);
+               crypto1_get_lfsr(state + i, &key_recovered);
+               *(state_s + i) = key_recovered;
+       }
+
+       qsort(state_s, i, sizeof(int64_t), compar_intA);
+       *(state_s + i) = -1;
+       
+       // first call to this function.  clear all other stuff and set new found states.
+       if (last_keylist == NULL) {
+               free(last_keylist);
+               last_keylist = state_s;
+               PrintAndLog("parity is all zero, testing special attack. First call, this attack needs at least two calls. Hold on...");                
+               PrintAndLog("uid(%08x) nt(%08x) ks(%016"llx") nr(%08x)\n", uid, nt, ks_info, nr);
+               return 1;
+       }
+
+       PrintAndLog("uid(%08x) nt(%08x) ks(%016"llx") nr(%08x)\n", uid, nt, ks_info, nr);
+               
+       //Create the intersection:
+       int64_t *p1, *p2, *p3;
+       p1 = p3 = last_keylist; 
+       p2 = state_s;
+               
+       while ( *p1 != -1 && *p2 != -1 ) {
+               if (compar_intA(p1, p2) == 0) {
+                       printf("p1:%"llx" p2:%"llx" p3:%"llx" key:%012"llx"\n",(uint64_t)(p1-last_keylist),(uint64_t)(p2-state_s),(uint64_t)(p3-last_keylist),*p1);
+                       *p3++ = *p1++;
+                       p2++;
+               }
+               else {
+                       while (compar_intA(p1, p2) == -1) ++p1;
+                       while (compar_intA(p1, p2) == 1) ++p2;
+               }
+       }
+       key_count = p3 - last_keylist;
+       printf("key_count: %d\n", key_count);
+       if ( key_count == 0 ){
+               free(state);
+               state = NULL;
+               return 0;
+       }
+       
+       uint8_t retval = 1;
+       // Validate all key candidates with testing each of them with mfCheckKeys
+       uint8_t keyBlock[6] = {0,0,0,0,0,0};
+       uint64_t key64;
+       for (i = 0; i < key_count; i++) {
+               key64 = *(last_keylist + i);
+               num_to_bytes(key64, 6, keyBlock);
+               key64 = 0;
+               if (!mfCheckKeys(blockno, keytype, false, 1, keyBlock, &key64)) {
+                       *key = key64;
+                       retval = 0;
+                       goto out;
+               }
+       }
+       
+out:
+       free(last_keylist);
+       last_keylist = NULL;
+       free(state);
+       state = NULL;
+       return retval;
+}