+ // tag nonce.\r
+ memcpy(enc_random_b,receivedAnswer+1,8);\r
+\r
+ // decrypt nonce.\r
+ tdes_2key_dec(random_b, enc_random_b, sizeof(random_b), key, IV );\r
+ rol(random_b,8);\r
+ memcpy(rnd_ab ,random_a,8);\r
+ memcpy(rnd_ab+8,random_b,8);\r
+ \r
+ // encrypt out, in, length, key, iv\r
+ tdes_2key_enc(rnd_ab, rnd_ab, sizeof(rnd_ab), key, enc_random_b);\r
+\r
+ len = mifare_sendcmd_short_mfucauth(NULL, 1, 0xAF, rnd_ab, receivedAnswer, receivedAnswerPar, NULL);\r
+ if (len != 11) {\r
+ OnError(1);\r
+ return;\r
+ }\r
+\r
+ uint8_t enc_resp[8] = { 0 };\r
+ uint8_t resp_random_a[8] = { 0 };\r
+ memcpy(enc_resp, receivedAnswer+1, 8);\r
+ \r
+ // decrypt out, in, length, key, iv \r
+ tdes_2key_dec(resp_random_a, enc_resp, 8, key, enc_random_b);\r
+ if ( memcmp(resp_random_a, random_a, 8) != 0 )\r
+ Dbprintf("failed authentication");\r
+ }\r
+ \r
+ for (int i = 0; i < blocks; i++){\r
+ \r
+ len = mifare_ultra_readblock(blockNo * 4 + i, dataout + 4 * i);\r