Merge pull request #504 from merlokk/emv3

[proxmark3-svn] / client / mifarehost.c

diff --git a/client/mifarehost.c b/client/mifarehost.c
index fe1a8edbab7b15b360285cf2d2713ad39881ccad..67277b5904aa3c0f58cf1974808944a869d9cf79 100644 (file)
--- a/client/mifarehost.c
+++ b/client/mifarehost.c
@@ -903,3 +903,72 @@ int tryDecryptWord(uint32_t nt, uint32_t ar_enc, uint32_t at_enc, uint8_t *data,
        return 0;\r
 }\r
 \r
        return 0;\r
 }\r
 \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