+\r
+/** validate_prng_nonce\r
+ * Determine if nonce is deterministic. ie: Suspectable to Darkside attack.\r
+ * returns\r
+ * true = weak prng\r
+ * false = hardend prng\r
+ */\r
+bool validate_prng_nonce(uint32_t nonce) {\r
+ uint16_t *dist = 0;\r
+ uint16_t x, i;\r
+\r
+ dist = malloc(2 << 16);\r
+ if(!dist)\r
+ return -1;\r
+\r
+ // init prng table:\r
+ for (x = i = 1; i; ++i) {\r
+ dist[(x & 0xff) << 8 | x >> 8] = i;\r
+ x = x >> 1 | (x ^ x >> 2 ^ x >> 3 ^ x >> 5) << 15;\r
+ }\r
+ \r
+ uint32_t res = (65535 - dist[nonce >> 16] + dist[nonce & 0xffff]) % 65535;\r
+ \r
+ free(dist); \r
+ return (res == 16);\r
+}\r
+\r
+/* Detect Tag Prng, \r
+* function performs a partial AUTH, where it tries to authenticate against block0, key A, but only collects tag nonce.\r
+* the tag nonce is check to see if it has a predictable PRNG.\r
+* @returns \r
+* TRUE if tag uses WEAK prng (ie Now the NACK bug also needs to be present for Darkside attack)\r
+* FALSE is tag uses HARDEND prng (ie hardnested attack possible, with known key)\r
+*/\r
+int DetectClassicPrng(void){\r
+\r
+ UsbCommand resp, respA; \r
+ uint8_t cmd[] = {0x60, 0x00}; // MIFARE_AUTH_KEYA\r
+ uint32_t flags = ISO14A_CONNECT | ISO14A_RAW | ISO14A_APPEND_CRC | ISO14A_NO_RATS;\r
+ \r
+ UsbCommand c = {CMD_READER_ISO_14443a, {flags, sizeof(cmd), 0}};\r
+ memcpy(c.d.asBytes, cmd, sizeof(cmd));\r
+\r
+ clearCommandBuffer();\r
+ SendCommand(&c);\r
+ if (!WaitForResponseTimeout(CMD_ACK, &resp, 2000)) {\r
+ PrintAndLog("PRNG UID: Reply timeout.");\r
+ return -1;\r
+ }\r
+ \r
+ // if select tag failed.\r
+ if (resp.arg[0] == 0) {\r
+ PrintAndLog("PRNG error: selecting tag failed, can't detect prng.");\r
+ return -1;\r
+ }\r
+ \r
+ if (!WaitForResponseTimeout(CMD_ACK, &respA, 5000)) {\r
+ PrintAndLog("PRNG data: Reply timeout.");\r
+ return -1;\r
+ }\r
+\r
+ // check respA\r
+ if (respA.arg[0] != 4) {\r
+ PrintAndLog("PRNG data error: Wrong length: %d", respA.arg[0]);\r
+ return -1;\r
+ }\r
+\r
+ uint32_t nonce = bytes_to_num(respA.d.asBytes, respA.arg[0]);\r
+ return validate_prng_nonce(nonce);\r
+}\r