From: pwpiwi Date: Sat, 24 Aug 2019 13:07:56 +0000 (+0200) Subject: iclass.c: speeding up MAC calculation X-Git-Url: https://git.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/commitdiff_plain/1477ba8a3c34f9b7eb624167251efea927755194?hp=17505ce2a74468c89747c996a72139aa9f3ca225 iclass.c: speeding up MAC calculation --- diff --git a/armsrc/iclass.c b/armsrc/iclass.c index ee305a26..5d7375a7 100644 --- a/armsrc/iclass.c +++ b/armsrc/iclass.c @@ -1146,7 +1146,7 @@ int doIClassSimulation(int simulationMode, uint8_t *reader_mac_buf) { memcpy(data_response, ToSend, ToSendMax); modulated_response = data_response; modulated_response_size = ToSendMax; - response_delay = 0;//We need to hurry here... + response_delay = 0; //We need to hurry here... (but maybe not too much... ??) //exitLoop = true; } else { //Not fullsim, we don't respond // We do not know what to answer, so lets keep quiet diff --git a/armsrc/optimized_cipher.c b/armsrc/optimized_cipher.c index ee9d5568..2ac72ec0 100644 --- a/armsrc/optimized_cipher.c +++ b/armsrc/optimized_cipher.c @@ -60,15 +60,63 @@ -- MHS 2015 **/ +/** + + The runtime of opt_doTagMAC_2() with the MHS optimized version was 403 microseconds on Proxmark3. + This was still to slow for some newer readers which didn't want to wait that long. + + Further optimizations to speedup the MAC calculations: + * Optimized opt_Tt logic + * Look up table for opt_select + * Removing many unnecessary bit maskings (& 0x1) + * updating state in place instead of alternating use of a second state structure + * remove the necessity to reverse bits of input and output bytes + + opt_doTagMAC_2() now completes in 270 microseconds. + + -- piwi 2019 +**/ + #include "optimized_cipher.h" #include #include #include - - -#define opt_T(s) (0x1 & ((s->t >> 15) ^ (s->t >> 14)^ (s->t >> 10)^ (s->t >> 8)^ (s->t >> 5)^ (s->t >> 4)^ (s->t >> 1)^ s->t)) - -#define opt_B(s) (((s->b >> 6) ^ (s->b >> 5) ^ (s->b >> 4) ^ (s->b)) & 0x1) +#include "string.h" + +static const uint8_t opt_select_LUT[256] = { + 00, 03, 02, 01, 02, 03, 00, 01, 04, 07, 07, 04, 06, 07, 05, 04, + 01, 02, 03, 00, 02, 03, 00, 01, 05, 06, 06, 05, 06, 07, 05, 04, + 06, 05, 04, 07, 04, 05, 06, 07, 06, 05, 05, 06, 04, 05, 07, 06, + 07, 04, 05, 06, 04, 05, 06, 07, 07, 04, 04, 07, 04, 05, 07, 06, + 06, 05, 04, 07, 04, 05, 06, 07, 02, 01, 01, 02, 00, 01, 03, 02, + 03, 00, 01, 02, 00, 01, 02, 03, 07, 04, 04, 07, 04, 05, 07, 06, + 00, 03, 02, 01, 02, 03, 00, 01, 00, 03, 03, 00, 02, 03, 01, 00, + 05, 06, 07, 04, 06, 07, 04, 05, 05, 06, 06, 05, 06, 07, 05, 04, + 02, 01, 00, 03, 00, 01, 02, 03, 06, 05, 05, 06, 04, 05, 07, 06, + 03, 00, 01, 02, 00, 01, 02, 03, 07, 04, 04, 07, 04, 05, 07, 06, + 02, 01, 00, 03, 00, 01, 02, 03, 02, 01, 01, 02, 00, 01, 03, 02, + 03, 00, 01, 02, 00, 01, 02, 03, 03, 00, 00, 03, 00, 01, 03, 02, + 04, 07, 06, 05, 06, 07, 04, 05, 00, 03, 03, 00, 02, 03, 01, 00, + 01, 02, 03, 00, 02, 03, 00, 01, 05, 06, 06, 05, 06, 07, 05, 04, + 04, 07, 06, 05, 06, 07, 04, 05, 04, 07, 07, 04, 06, 07, 05, 04, + 01, 02, 03, 00, 02, 03, 00, 01, 01, 02, 02, 01, 02, 03, 01, 00 +}; + +/********************** the table above has been generated with this code: ******** +#include "util.h" +static void init_opt_select_LUT(void) { + for (int r = 0; r < 256; r++) { + uint8_t r_ls2 = r << 2; + uint8_t r_and_ls2 = r & r_ls2; + uint8_t r_or_ls2 = r | r_ls2; + uint8_t z0 = (r_and_ls2 >> 5) ^ ((r & ~r_ls2) >> 4) ^ ( r_or_ls2 >> 3); + uint8_t z1 = (r_or_ls2 >> 6) ^ ( r_or_ls2 >> 1) ^ (r >> 5) ^ r; + uint8_t z2 = ((r & ~r_ls2) >> 4) ^ (r_and_ls2 >> 3) ^ r; + opt_select_LUT[r] = (z0 & 4) | (z1 & 2) | (z2 & 1); + } + print_result("", opt_select_LUT, 256); +} +***********************************************************************************/ #define opt__select(x,y,r) (4 & (((r & (r << 2)) >> 5) ^ ((r & ~(r << 2)) >> 4) ^ ( (r | r << 2) >> 3)))\ |(2 & (((r | r << 2) >> 6) ^ ( (r | r << 2) >> 1) ^ (r >> 5) ^ r ^ ((x^y) << 1)))\ @@ -78,9 +126,6 @@ * Some background on the expression above can be found here... uint8_t xopt__select(bool x, bool y, uint8_t r) { - uint8_t r_ls2 = r << 2; - uint8_t r_and_ls2 = r & r_ls2; - uint8_t r_or_ls2 = r | r_ls2; //r: r0 r1 r2 r3 r4 r5 r6 r7 //r_ls2: r2 r3 r4 r5 r6 r7 0 0 @@ -100,81 +145,95 @@ uint8_t xopt__select(bool x, bool y, uint8_t r) } */ -void opt_successor(const uint8_t *k, State *s, bool y, State *successor) { - uint8_t Tt = 1 & opt_T(s); - - successor->t = (s->t >> 1); - successor->t |= (Tt ^ (s->r >> 7 & 0x1) ^ (s->r >> 3 & 0x1)) << 15; - - successor->b = s->b >> 1; - successor->b |= (opt_B(s) ^ (s->r & 0x1)) << 7; - - successor->r = (k[opt__select(Tt, y, s->r)] ^ successor->b) + s->l ; - successor->l = successor->r + s->r; +static void opt_successor(const uint8_t *k, State *s, uint8_t y) { +// #define opt_T(s) (0x1 & ((s->t >> 15) ^ (s->t >> 14) ^ (s->t >> 10) ^ (s->t >> 8) ^ (s->t >> 5) ^ (s->t >> 4)^ (s->t >> 1) ^ s->t)) + // uint8_t Tt = opt_T(s); + uint16_t Tt = s->t & 0xc533; + Tt = Tt ^ (Tt >> 1); + Tt = Tt ^ (Tt >> 4); + Tt = Tt ^ (Tt >> 10); + Tt = Tt ^ (Tt >> 8); + + s->t = (s->t >> 1); + s->t |= (Tt ^ (s->r >> 7) ^ (s->r >> 3)) << 15; + + uint8_t opt_B = s->b; + opt_B ^= s->b >> 6; + opt_B ^= s->b >> 5; + opt_B ^= s->b >> 4; + + s->b = s->b >> 1; + s->b |= (opt_B ^ s->r) << 7; + + uint8_t opt_select = opt_select_LUT[s->r] & 0x04; + opt_select |= (opt_select_LUT[s->r] ^ ((Tt ^ y) << 1)) & 0x02; + opt_select |= (opt_select_LUT[s->r] ^ Tt) & 0x01; + + uint8_t r = s->r; + s->r = (k[opt_select] ^ s->b) + s->l ; + s->l = s->r + r; } -void opt_suc(const uint8_t *k, State *s, uint8_t *in, uint8_t length, bool add32Zeroes) { - State x2; +static void opt_suc(const uint8_t *k, State *s, uint8_t *in, uint8_t length, bool add32Zeroes) { for (int i = 0; i < length; i++) { uint8_t head; - head = 1 & (in[i] >> 7); - opt_successor(k, s, head, &x2); + head = in[i]; + opt_successor(k, s, head); - head = 1 & (in[i] >> 6); - opt_successor(k, &x2, head, s); + head >>= 1; + opt_successor(k, s, head); - head = 1 & (in[i] >> 5); - opt_successor(k, s, head, &x2); + head >>= 1; + opt_successor(k, s, head); - head = 1 & (in[i] >> 4); - opt_successor(k, &x2, head, s); + head >>= 1; + opt_successor(k, s, head); - head = 1 & (in[i] >> 3); - opt_successor(k, s, head, &x2); + head >>= 1; + opt_successor(k, s, head); - head = 1 & (in[i] >> 2); - opt_successor(k, &x2, head, s); + head >>= 1; + opt_successor(k, s, head); - head = 1 & (in[i] >> 1); - opt_successor(k, s, head, &x2); + head >>= 1; + opt_successor(k, s, head); - head = 1 & in[i]; - opt_successor(k, &x2, head, s); + head >>= 1; + opt_successor(k, s, head); } //For tag MAC, an additional 32 zeroes if (add32Zeroes) { for(int i = 0; i < 16; i++) { - opt_successor(k, s, 0, &x2); - opt_successor(k, &x2, 0, s); + opt_successor(k, s, 0); + opt_successor(k, s, 0); } } } -void opt_output(const uint8_t *k, State *s, uint8_t *buffer) { - State temp = {0, 0, 0, 0}; +static void opt_output(const uint8_t *k, State *s, uint8_t *buffer) { for (uint8_t times = 0; times < 4; times++) { uint8_t bout = 0; - bout |= (s->r & 0x4) << 5; - opt_successor(k, s, 0, &temp); - bout |= (temp.r & 0x4) << 4; - opt_successor(k, &temp, 0, s); - bout |= (s->r & 0x4) << 3; - opt_successor(k, s, 0, &temp); - bout |= (temp.r & 0x4) << 2; - opt_successor(k, &temp, 0, s); - bout |= (s->r & 0x4) << 1; - opt_successor(k, s, 0, &temp); - bout |= (temp.r & 0x4) ; - opt_successor(k, &temp, 0, s); + bout |= (s->r & 0x4) >> 2; + opt_successor(k, s, 0); bout |= (s->r & 0x4) >> 1; - opt_successor(k, s, 0, &temp); - bout |= (temp.r & 0x4) >> 2; - opt_successor(k, &temp, 0, s); + opt_successor(k, s, 0); + bout |= (s->r & 0x4); + opt_successor(k, s, 0); + bout |= (s->r & 0x4) << 1; + opt_successor(k, s, 0); + bout |= (s->r & 0x4) << 2; + opt_successor(k, s, 0); + bout |= (s->r & 0x4) << 3; + opt_successor(k, s, 0); + bout |= (s->r & 0x4) << 4; + opt_successor(k, s, 0); + bout |= (s->r & 0x4) << 5; + opt_successor(k, s, 0); buffer[times] = bout; } } -void opt_MAC(uint8_t *k, uint8_t *input, uint8_t *out) { +static void opt_MAC(uint8_t *k, uint8_t *input, uint8_t *out) { State _init = { ((k[0] ^ 0x4c) + 0xEC) & 0xFF,// l ((k[0] ^ 0x4c) + 0x21) & 0xFF,// r @@ -187,43 +246,22 @@ void opt_MAC(uint8_t *k, uint8_t *input, uint8_t *out) { opt_output(k, &_init, out); } -uint8_t rev_byte(uint8_t b) { - b = (b & 0xF0) >> 4 | (b & 0x0F) << 4; - b = (b & 0xCC) >> 2 | (b & 0x33) << 2; - b = (b & 0xAA) >> 1 | (b & 0x55) << 1; - return b; -} - -void opt_reverse_arraybytecpy(uint8_t *dest, uint8_t *src, size_t len) { - for (size_t i = 0; i < len; i++) { - dest[i] = rev_byte(src[i]); - } -} - void opt_doReaderMAC(uint8_t *cc_nr_p, uint8_t *div_key_p, uint8_t mac[4]) { - static uint8_t cc_nr[12]; - opt_reverse_arraybytecpy(cc_nr, cc_nr_p, 12); uint8_t dest[] = {0, 0, 0, 0, 0, 0, 0, 0}; - opt_MAC(div_key_p, cc_nr, dest); - //The output MAC must also be reversed - opt_reverse_arraybytecpy(mac, dest, 4); + opt_MAC(div_key_p, cc_nr_p, dest); + memcpy(mac, dest, 4); return; } void opt_doTagMAC(uint8_t *cc_p, const uint8_t *div_key_p, uint8_t mac[4]) { - static uint8_t cc_nr[8+4+4]; - opt_reverse_arraybytecpy(cc_nr, cc_p, 12); State _init = { ((div_key_p[0] ^ 0x4c) + 0xEC) & 0xFF,// l ((div_key_p[0] ^ 0x4c) + 0x21) & 0xFF,// r 0x4c, // b 0xE012 // t }; - opt_suc(div_key_p, &_init,cc_nr, 12, true); - uint8_t dest[] = {0, 0, 0, 0}; - opt_output(div_key_p, &_init, dest); - //The output MAC must also be reversed - opt_reverse_arraybytecpy(mac, dest, 4); + opt_suc(div_key_p, &_init, cc_p, 12, true); + opt_output(div_key_p, &_init, mac); return; } @@ -236,15 +274,13 @@ void opt_doTagMAC(uint8_t *cc_p, const uint8_t *div_key_p, uint8_t mac[4]) { * @return the cipher state */ State opt_doTagMAC_1(uint8_t *cc_p, const uint8_t *div_key_p) { - static uint8_t cc_nr[8]; - opt_reverse_arraybytecpy(cc_nr, cc_p, 8); State _init = { ((div_key_p[0] ^ 0x4c) + 0xEC) & 0xFF,// l ((div_key_p[0] ^ 0x4c) + 0x21) & 0xFF,// r 0x4c, // b 0xE012 // t }; - opt_suc(div_key_p, &_init, cc_nr, 8, false); + opt_suc(div_key_p, &_init, cc_p, 8, false); return _init; } @@ -258,13 +294,7 @@ State opt_doTagMAC_1(uint8_t *cc_p, const uint8_t *div_key_p) { * @param div_key_p - the key to use */ void opt_doTagMAC_2(State _init, uint8_t *nr, uint8_t mac[4], const uint8_t *div_key_p) { - static uint8_t _nr[4]; - opt_reverse_arraybytecpy(_nr, nr, 4); - opt_suc(div_key_p, &_init, _nr, 4, true); - //opt_suc(div_key_p, &_init,nr, 4, false); - uint8_t dest[] = {0, 0, 0, 0}; - opt_output(div_key_p, &_init, dest); - //The output MAC must also be reversed - opt_reverse_arraybytecpy(mac, dest, 4); + opt_suc(div_key_p, &_init, nr, 4, true); + opt_output(div_key_p, &_init, mac); return; }