+/*
+ * Hitag2 emulation
+ *
+ * Contains state and functions for an emulated Hitag2 tag. Offers an entry
+ * point to handle commands, needs a callback to send response.
+ *
+ * (c) 2009 Henryk Plötz <henryk@ploetzli.ch>
+ */
+
+#include <proxmark3.h>
+#include <stdint.h>
+
+#include "apps.h"
+#include "hitag2.h"
+
+struct hitag2_cipher_state {
+ uint64_t state;
+};
+
+struct hitag2_tag {
+ uint32_t uid;
+ enum {
+ TAG_STATE_RESET, // Just powered up, awaiting GetSnr
+ TAG_STATE_ACTIVATING, // In activation phase (password mode), sent UID, awaiting reader password
+ TAG_STATE_AUTHENTICATING, // In activation phase (crypto mode), awaiting reader authentication
+ TAG_STATE_ACTIVATED, // Activation complete, awaiting read/write commands
+ TAG_STATE_WRITING, // In write command, awaiting sector contents to be written
+ } state;
+ unsigned int active_sector;
+ char crypto_active;
+ struct hitag2_cipher_state cs;
+ char sectors[8][4];
+};
+
+static void hitag2_cipher_reset(struct hitag2_tag *tag, const char *challenge);
+static int hitag2_cipher_authenticate(struct hitag2_cipher_state *cs, const char *authenticator);
+static int hitag2_cipher_transcrypt(struct hitag2_cipher_state *cs, char *data, unsigned int bytes, unsigned int bits);
+
+static struct hitag2_tag tag;
+static const struct hitag2_tag resetdata = {
+ .state = TAG_STATE_RESET,
+ .sectors = { // Password mode: | Crypto mode:
+ [0] = { 0x35, 0x33, 0x70, 0x11}, // UID | UID
+ [1] = { 0x4d, 0x49, 0x4b, 0x52}, // Password RWD | 32 bit LSB key
+ [2] = { 0x20, 0xf0, 0x4f, 0x4e}, // Reserved | 16 bit MSB key, 16 bit reserved
+ [3] = { 0x0e, 0xaa, 'H', 'T'}, // Configuration, password TAG | Configuration, password TAG
+ },
+};
+
+int hitag2_reset(void)
+{
+ tag.state = TAG_STATE_RESET;
+ tag.crypto_active = 0;
+ return 0;
+}
+
+int hitag2_init(void)
+{
+ memcpy(&tag, &resetdata, sizeof(tag));
+ hitag2_reset();
+ return 0;
+}
+
+int hitag2_handle_command(const char* data, const int length, hitag2_response_callback_t cb, void *cb_cookie)
+{
+ (void)data; (void)length; (void)cb; (void)cb_cookie;
+ int retry = 0, done = 0, result=0;
+ char temp[10];
+
+ if(tag.crypto_active && length < sizeof(temp)*8) {
+ /* Decrypt command */
+ memcpy(temp, data, (length+7)/8);
+ hitag2_cipher_transcrypt(&(tag.cs), temp, length/8, length%8);
+ data = temp;
+ }
+
+
+handle_command_retry:
+ switch(tag.state) {
+ case TAG_STATE_RESET:
+ if(length == 5 && data[0] == 0xC0) {
+ /* Received 11000 from the reader, request for UID, send UID */
+ result=cb(tag.sectors[0], sizeof(tag.sectors[0])*8, 208, cb_cookie);
+ done=1;
+ if(tag.sectors[3][0] & 0x08) {
+ tag.state=TAG_STATE_AUTHENTICATING;
+ } else {
+ tag.state=TAG_STATE_ACTIVATING;
+ }
+ }
+ break;
+ case TAG_STATE_ACTIVATING:
+ if(length == 0x20) {
+ /* Received RWD password, respond with configuration and our password */
+ result=cb(tag.sectors[3], sizeof(tag.sectors[3])*8, 208, cb_cookie);
+ done=1;
+ tag.state=TAG_STATE_ACTIVATED;
+ }
+ break;
+ case TAG_STATE_AUTHENTICATING:
+ if(length == 0x40) {
+ /* Received initialisation vector || authentication token, fire up cipher, send our password */
+ hitag2_cipher_reset(&tag, data);
+ if(hitag2_cipher_authenticate(&(tag.cs), data+4)) {
+ char response_enc[4];
+ memcpy(response_enc, tag.sectors[3], 4);
+ hitag2_cipher_transcrypt(&(tag.cs), response_enc, 4, 0);
+ result=cb(response_enc, 4*8, 208, cb_cookie);
+ done=1;
+ tag.crypto_active = 1;
+ tag.state = TAG_STATE_ACTIVATED;
+ } else {
+ /* The reader failed to authenticate, do nothing */
+ DbpString("Reader authentication failed");
+ }
+ }
+ break;
+ case TAG_STATE_ACTIVATED:
+ if(length == 10) {
+ if( ((data[0] & 0xC0) == 0xC0) && ((data[0] & 0x06) == 0) ) {
+ /* Read command: 11xx x00y yy with yyy == ~xxx, xxx is sector number */
+ unsigned int sector = (~( ((data[0]<<2)&0x04) | ((data[1]>>6)&0x03) ) & 0x07);
+ if(sector == ( (data[0]>>3)&0x07 ) ) {
+ memcpy(temp, tag.sectors[sector], 4);
+ if(tag.crypto_active) {
+ hitag2_cipher_transcrypt(&(tag.cs), temp, 4, 0);
+ }
+ /* Respond with contents of sector sector */
+ result = cb(temp, 4*8, 208, cb_cookie);
+ done=1;
+ } else {
+ /* transmission error */
+ DbpString("Transmission error (read) in activated state");
+ }
+ } else if( ((data[0] & 0xC0) == 0x80) && ((data[0] & 0x06) == 2) ) {
+ /* Write command: 10xx x01y yy with yyy == ~xxx, xxx is sector number */
+ unsigned int sector = (~( ((data[0]<<2)&0x04) | ((data[1]>>6)&0x03) ) & 0x07);
+ if(sector == ( (data[0]>>3)&0x07 ) ) {
+ /* Prepare write, acknowledge by repeating command */
+ if(tag.crypto_active) {
+ hitag2_cipher_transcrypt(&(tag.cs), temp, length/8, length%8);
+ }
+ result = cb(data, length, 208, cb_cookie);
+ done=1;
+ tag.active_sector = sector;
+ tag.state=TAG_STATE_WRITING;
+ } else {
+ /* transmission error */
+ DbpString("Transmission error (write) in activated state");
+ }
+ }
+
+ }
+ case TAG_STATE_WRITING:
+ if(length == 32) {
+ /* These are the sector contents to be written. We don't have to do anything else. */
+ memcpy(tag.sectors[tag.active_sector], data, length/8);
+ tag.state=TAG_STATE_ACTIVATED;
+ done=1;
+ }
+ }
+
+ if(!done && !retry) {
+ /* We didn't respond, maybe our state is faulty. Reset and try again. */
+ retry=1;
+ if(tag.crypto_active) {
+ /* Restore undeciphered data */
+ memcpy(temp, data, (length+7)/8);
+ }
+ hitag2_reset();
+ goto handle_command_retry;
+ }
+
+ return result;
+}
+
+/* Following is a modified version of cryptolib.com/ciphers/hitag2/ */
+// Software optimized 48-bit Philips/NXP Mifare Hitag2 PCF7936/46/47/52 stream cipher algorithm by I.C. Wiener 2006-2007.
+// For educational purposes only.
+// No warranties or guarantees of any kind.
+// This code is released into the public domain by its author.
+
+// Basic macros:
+
+#define u8 uint8_t
+#define u32 uint32_t
+#define u64 uint64_t
+#define rev8(x) ((((x)>>7)&1)+((((x)>>6)&1)<<1)+((((x)>>5)&1)<<2)+((((x)>>4)&1)<<3)+((((x)>>3)&1)<<4)+((((x)>>2)&1)<<5)+((((x)>>1)&1)<<6)+(((x)&1)<<7))
+#define rev16(x) (rev8 (x)+(rev8 (x>> 8)<< 8))
+#define rev32(x) (rev16(x)+(rev16(x>>16)<<16))
+#define rev64(x) (rev32(x)+(rev32(x>>32)<<32))
+#define bit(x,n) (((x)>>(n))&1)
+#define bit32(x,n) ((((x)[(n)>>5])>>((n)))&1)
+#define inv32(x,i,n) ((x)[(i)>>5]^=((u32)(n))<<((i)&31))
+#define rotl64(x, n) ((((u64)(x))<<((n)&63))+(((u64)(x))>>((0-(n))&63)))
+
+// Single bit Hitag2 functions:
+
+#define i4(x,a,b,c,d) ((u32)((((x)>>(a))&1)+(((x)>>(b))&1)*2+(((x)>>(c))&1)*4+(((x)>>(d))&1)*8))
+
+static const u32 ht2_f4a = 0x2C79; // 0010 1100 0111 1001
+static const u32 ht2_f4b = 0x6671; // 0110 0110 0111 0001
+static const u32 ht2_f5c = 0x7907287B; // 0111 1001 0000 0111 0010 1000 0111 1011
+
+static u32 _f20 (const u64 x)
+{
+ u32 i5;
+
+ i5 = ((ht2_f4a >> i4 (x, 1, 2, 4, 5)) & 1)* 1
+ + ((ht2_f4b >> i4 (x, 7,11,13,14)) & 1)* 2
+ + ((ht2_f4b >> i4 (x,16,20,22,25)) & 1)* 4
+ + ((ht2_f4b >> i4 (x,27,28,30,32)) & 1)* 8
+ + ((ht2_f4a >> i4 (x,33,42,43,45)) & 1)*16;
+
+ return (ht2_f5c >> i5) & 1;
+}
+
+static u64 _hitag2_init (const u64 key, const u32 serial, const u32 IV)
+{
+ u32 i;
+ u64 x = ((key & 0xFFFF) << 32) + serial;
+
+ for (i = 0; i < 32; i++)
+ {
+ x >>= 1;
+ x += (u64) (_f20 (x) ^ (((IV >> i) ^ (key >> (i+16))) & 1)) << 47;
+ }
+ return x;
+}
+
+static u64 _hitag2_round (u64 *state)
+{
+ u64 x = *state;
+
+ x = (x >> 1) +
+ ((((x >> 0) ^ (x >> 2) ^ (x >> 3) ^ (x >> 6)
+ ^ (x >> 7) ^ (x >> 8) ^ (x >> 16) ^ (x >> 22)
+ ^ (x >> 23) ^ (x >> 26) ^ (x >> 30) ^ (x >> 41)
+ ^ (x >> 42) ^ (x >> 43) ^ (x >> 46) ^ (x >> 47)) & 1) << 47);
+
+ *state = x;
+ return _f20 (x);
+}
+
+// Bitslice Hitag2 functions:
+
+#define ht2bs_4a(a,b,c,d) (~(((a|b)&c)^(a|d)^b))
+#define ht2bs_4b(a,b,c,d) (~(((d|c)&(a^b))^(d|a|b)))
+#define ht2bs_5c(a,b,c,d,e) (~((((((c^e)|d)&a)^b)&(c^b))^(((d^e)|a)&((d^b)|c))))
+
+#define uf20bs u32 // choose your own type/width
+
+static uf20bs _f20bs (const uf20bs *x)
+{
+ return ht2bs_5c (
+ ht2bs_4a(x[ 1],x[ 2],x[ 4],x[ 5]),
+ ht2bs_4b(x[ 7],x[11],x[13],x[14]),
+ ht2bs_4b(x[16],x[20],x[22],x[25]),
+ ht2bs_4b(x[27],x[28],x[30],x[32]),
+ ht2bs_4a(x[33],x[42],x[43],x[45]));
+}
+
+static void _hitag2bs_init (uf20bs *x, const uf20bs *key, const uf20bs *serial, const uf20bs *IV)
+{
+ u32 i, r;
+
+ for (i = 0; i < 32; i++) x[i] = serial[i];
+ for (i = 0; i < 16; i++) x[32+i] = key[i];
+
+ for (r = 0; r < 32; r++)
+ {
+ for (i = 0; i < 47; i++) x[i] = x[i+1];
+ x[47] = _f20bs (x) ^ IV[i] ^ key[16+i];
+ }
+}
+
+static uf20bs _hitag2bs_round (uf20bs *x)
+{
+ uf20bs y;
+ u32 i;
+
+ y = x[ 0] ^ x[ 2] ^ x[ 3] ^ x[ 6] ^ x[ 7] ^ x[ 8] ^ x[16] ^ x[22]
+ ^ x[23] ^ x[26] ^ x[30] ^ x[41] ^ x[42] ^ x[43] ^ x[46] ^ x[47];
+
+ for (i = 0; i < 47; i++) x[i] = x[i+1];
+ x[47] = y;
+
+ return _f20bs (x);
+}
+
+static u32 _hitag2_byte (u64 * x)
+{
+ u32 i, c;
+
+ for (i = 0, c = 0; i < 8; i++) c += (u32) _hitag2_round (x) << (i^7);
+ return c;
+}
+
+
+/* Cipher/tag glue code: */
+
+static void hitag2_cipher_reset(struct hitag2_tag *tag, const char *iv)
+{
+ uint64_t key = ((uint64_t)tag->sectors[2][2]) |
+ ((uint64_t)tag->sectors[2][3] << 8) |
+ ((uint64_t)tag->sectors[1][0] << 16) |
+ ((uint64_t)tag->sectors[1][1] << 24) |
+ ((uint64_t)tag->sectors[1][2] << 32) |
+ ((uint64_t)tag->sectors[1][3] << 40);
+ uint32_t uid = ((uint32_t)tag->sectors[0][0]) |
+ ((uint32_t)tag->sectors[0][1] << 8) |
+ ((uint32_t)tag->sectors[0][2] << 16) |
+ ((uint32_t)tag->sectors[0][3] << 24);
+ uint32_t iv_ = (((uint32_t)(iv[0]))) |
+ (((uint32_t)(iv[1])) << 8) |
+ (((uint32_t)(iv[2])) << 16) |
+ (((uint32_t)(iv[3])) << 24);
+ tag->cs.state = _hitag2_init(rev64(key), rev32(uid), rev32(iv_));
+}
+
+static int hitag2_cipher_authenticate(struct hitag2_cipher_state *cs, const char *authenticator_is)
+{
+ char authenticator_should[4];
+ authenticator_should[0] = ~_hitag2_byte(&(cs->state));
+ authenticator_should[1] = ~_hitag2_byte(&(cs->state));
+ authenticator_should[2] = ~_hitag2_byte(&(cs->state));
+ authenticator_should[3] = ~_hitag2_byte(&(cs->state));
+ return memcmp(authenticator_should, authenticator_is, 4) == 0;
+}
+
+static int hitag2_cipher_transcrypt(struct hitag2_cipher_state *cs, char *data, unsigned int bytes, unsigned int bits)
+{
+ int i;
+ for(i=0; i<bytes; i++) data[i] ^= _hitag2_byte(&(cs->state));
+ for(i=0; i<bits; i++) data[bytes] ^= _hitag2_round(&(cs->state)) << (7-i);
+ return 0;
+}
projects / proxmark3-svn / commitdiff