add loclass

application.fam

@@ -30,6 +30,10 @@ App(
             name="asn1",
             cflags=["-Wno-error"],
         ),
+        Lib(
+            name="loclass",
+            cflags=["-O3"],
+        ),
     ],
     fap_weburl="https://seader.ericbetts.dev",
     fap_icon_assets="icons",

lib/loclass/optimized_cipher.c

@@ -0,0 +1,319 @@
+//-----------------------------------------------------------------------------
+// Borrowed initially from https://github.com/holiman/loclass
+// Copyright (C) 2014 Martin Holst Swende
+// Copyright (C) Proxmark3 contributors. See AUTHORS.md for details.
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// See LICENSE.txt for the text of the license.
+//-----------------------------------------------------------------------------
+// WARNING
+//
+// THIS CODE IS CREATED FOR EXPERIMENTATION AND EDUCATIONAL USE ONLY.
+//
+// USAGE OF THIS CODE IN OTHER WAYS MAY INFRINGE UPON THE INTELLECTUAL
+// PROPERTY OF OTHER PARTIES, SUCH AS INSIDE SECURE AND HID GLOBAL,
+// AND MAY EXPOSE YOU TO AN INFRINGEMENT ACTION FROM THOSE PARTIES.
+//
+// THIS CODE SHOULD NEVER BE USED TO INFRINGE PATENTS OR INTELLECTUAL PROPERTY RIGHTS.
+//-----------------------------------------------------------------------------
+// It is a reconstruction of the cipher engine used in iClass, and RFID techology.
+//
+// The implementation is based on the work performed by
+// Flavio D. Garcia, Gerhard de Koning Gans, Roel Verdult and
+// Milosch Meriac in the paper "Dismantling IClass".
+//-----------------------------------------------------------------------------
+/*
+  This file contains an optimized version of the MAC-calculation algorithm. Some measurements on
+  a std laptop showed it runs in about 1/3 of the time:
+
+    Std: 0.428962
+    Opt: 0.151609
+
+  Additionally, it is self-reliant, not requiring e.g. bitstreams from the cipherutils, thus can
+  be easily dropped into a code base.
+
+  The optimizations have been performed in the following steps:
+  * Parameters passed by reference instead of by value.
+  * Iteration instead of recursion, un-nesting recursive loops into for-loops.
+  * Handling of bytes instead of individual bits, for less shuffling and masking
+  * Less creation of "objects", structs, and instead reuse of alloc:ed memory
+  * Inlining some functions via #define:s
+
+  As a consequence, this implementation is less generic. Also, I haven't bothered documenting this.
+  For a thorough documentation, check out the MAC-calculation within cipher.c instead.
+
+  -- 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
+**/
+
+/**
+  add the possibility to do iCLASS on device only
+  -- iceman 2020
+**/
+
+#include "optimized_cipher.h"
+#include "optimized_elite.h"
+#include "optimized_ikeys.h"
+#include "optimized_cipherutils.h"
+
+static const uint8_t loclass_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;
+        loclass_opt_select_LUT[r] = (z0 & 4) | (z1 & 2) | (z2 & 1);
+    }
+    print_result("", loclass_opt_select_LUT, 256);
+}
+***********************************************************************************/
+
+static inline void loclass_opt_successor(const uint8_t* k, LoclassState_t* s, uint8_t y) {
+    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 Tt1 = Tt & 0x01;
+    uint8_t opt_select = loclass_opt_select_LUT[s->r] ^ Tt1 ^ ((Tt1 ^ (y & 0x01)) << 1);
+
+    uint8_t r = s->r;
+    s->r = (k[opt_select] ^ s->b) + s->l;
+    s->l = s->r + r;
+}
+
+static inline void loclass_opt_suc(
+    const uint8_t* k,
+    LoclassState_t* s,
+    const uint8_t* in,
+    uint8_t length,
+    bool add32Zeroes) {
+    for(int i = 0; i < length; i++) {
+        uint8_t head = in[i];
+#pragma GCC unroll 8
+        for(int j = 0; j < 8; j++) {
+            loclass_opt_successor(k, s, head);
+            head >>= 1;
+        }
+    }
+    // For tag MAC, an additional 32 zeroes
+    if(add32Zeroes) {
+        for(int i = 0; i < 32; i++) {
+            loclass_opt_successor(k, s, 0);
+        }
+    }
+}
+
+static inline void loclass_opt_output(const uint8_t* k, LoclassState_t* s, uint8_t* buffer) {
+#pragma GCC unroll 4
+    for(uint8_t times = 0; times < 4; times++) {
+        uint8_t bout = 0;
+        bout |= (s->r & 0x4) >> 2;
+        loclass_opt_successor(k, s, 0);
+        bout |= (s->r & 0x4) >> 1;
+        loclass_opt_successor(k, s, 0);
+        bout |= (s->r & 0x4);
+        loclass_opt_successor(k, s, 0);
+        bout |= (s->r & 0x4) << 1;
+        loclass_opt_successor(k, s, 0);
+        bout |= (s->r & 0x4) << 2;
+        loclass_opt_successor(k, s, 0);
+        bout |= (s->r & 0x4) << 3;
+        loclass_opt_successor(k, s, 0);
+        bout |= (s->r & 0x4) << 4;
+        loclass_opt_successor(k, s, 0);
+        bout |= (s->r & 0x4) << 5;
+        loclass_opt_successor(k, s, 0);
+        buffer[times] = bout;
+    }
+}
+
+static void loclass_opt_MAC(uint8_t* k, uint8_t* input, uint8_t* out) {
+    LoclassState_t _init = {
+        ((k[0] ^ 0x4c) + 0xEC) & 0xFF, // l
+        ((k[0] ^ 0x4c) + 0x21) & 0xFF, // r
+        0x4c, // b
+        0xE012 // t
+    };
+
+    loclass_opt_suc(k, &_init, input, 12, false);
+    loclass_opt_output(k, &_init, out);
+}
+
+static void loclass_opt_MAC_N(uint8_t* k, uint8_t* input, uint8_t in_size, uint8_t* out) {
+    LoclassState_t _init = {
+        ((k[0] ^ 0x4c) + 0xEC) & 0xFF, // l
+        ((k[0] ^ 0x4c) + 0x21) & 0xFF, // r
+        0x4c, // b
+        0xE012 // t
+    };
+
+    loclass_opt_suc(k, &_init, input, in_size, false);
+    loclass_opt_output(k, &_init, out);
+}
+
+void loclass_opt_doReaderMAC(uint8_t* cc_nr_p, uint8_t* div_key_p, uint8_t mac[4]) {
+    uint8_t dest[] = {0, 0, 0, 0, 0, 0, 0, 0};
+    loclass_opt_MAC(div_key_p, cc_nr_p, dest);
+    memcpy(mac, dest, 4);
+}
+
+void loclass_opt_doReaderMAC_2(
+    LoclassState_t _init,
+    uint8_t* nr,
+    uint8_t mac[4],
+    const uint8_t* div_key_p) {
+    loclass_opt_suc(div_key_p, &_init, nr, 4, false);
+    loclass_opt_output(div_key_p, &_init, mac);
+}
+
+void loclass_doMAC_N(uint8_t* in_p, uint8_t in_size, uint8_t* div_key_p, uint8_t mac[4]) {
+    uint8_t dest[] = {0, 0, 0, 0, 0, 0, 0, 0};
+    loclass_opt_MAC_N(div_key_p, in_p, in_size, dest);
+    memcpy(mac, dest, 4);
+}
+
+void loclass_opt_doTagMAC(uint8_t* cc_p, const uint8_t* div_key_p, uint8_t mac[4]) {
+    LoclassState_t _init = {
+        ((div_key_p[0] ^ 0x4c) + 0xEC) & 0xFF, // l
+        ((div_key_p[0] ^ 0x4c) + 0x21) & 0xFF, // r
+        0x4c, // b
+        0xE012 // t
+    };
+    loclass_opt_suc(div_key_p, &_init, cc_p, 12, true);
+    loclass_opt_output(div_key_p, &_init, mac);
+}
+
+/**
+ * The tag MAC can be divided (both can, but no point in dividing the reader mac) into
+ * two functions, since the first 8 bytes are known, we can pre-calculate the state
+ * reached after feeding CC to the cipher.
+ * @param cc_p
+ * @param div_key_p
+ * @return the cipher state
+ */
+LoclassState_t loclass_opt_doTagMAC_1(uint8_t* cc_p, const uint8_t* div_key_p) {
+    LoclassState_t _init = {
+        ((div_key_p[0] ^ 0x4c) + 0xEC) & 0xFF, // l
+        ((div_key_p[0] ^ 0x4c) + 0x21) & 0xFF, // r
+        0x4c, // b
+        0xE012 // t
+    };
+    loclass_opt_suc(div_key_p, &_init, cc_p, 8, false);
+    return _init;
+}
+
+/**
+ * The second part of the tag MAC calculation, since the CC is already calculated into the state,
+ * this function is fed only the NR, and internally feeds the remaining 32 0-bits to generate the tag
+ * MAC response.
+ * @param _init - precalculated cipher state
+ * @param nr - the reader challenge
+ * @param mac - where to store the MAC
+ * @param div_key_p - the key to use
+ */
+void loclass_opt_doTagMAC_2(
+    LoclassState_t _init,
+    uint8_t* nr,
+    uint8_t mac[4],
+    const uint8_t* div_key_p) {
+    loclass_opt_suc(div_key_p, &_init, nr, 4, true);
+    loclass_opt_output(div_key_p, &_init, mac);
+}
+
+/**
+ * The second part of the tag MAC calculation, since the CC is already calculated into the state,
+ * this function is fed only the NR, and generates both the reader and tag MACs.
+ * @param _init - precalculated cipher state
+ * @param nr - the reader challenge
+ * @param rmac - where to store the reader MAC
+ * @param tmac - where to store the tag MAC
+ * @param div_key_p - the key to use
+ */
+void loclass_opt_doBothMAC_2(
+    LoclassState_t _init,
+    uint8_t* nr,
+    uint8_t rmac[4],
+    uint8_t tmac[4],
+    const uint8_t* div_key_p) {
+    LoclassState_t* s = &_init;
+    loclass_opt_suc(div_key_p, s, nr, 4, false);
+    loclass_opt_output(div_key_p, s, rmac);
+    loclass_opt_output(div_key_p, s, tmac);
+}
+
+void loclass_iclass_calc_div_key(
+    const uint8_t* csn,
+    const uint8_t* key,
+    uint8_t* div_key,
+    bool elite) {
+    if(elite) {
+        uint8_t keytable[128] = {0};
+        uint8_t key_index[8] = {0};
+        uint8_t key_sel[8] = {0};
+        uint8_t key_sel_p[8] = {0};
+        loclass_hash2(key, keytable);
+        loclass_hash1(csn, key_index);
+        for(uint8_t i = 0; i < 8; i++) key_sel[i] = keytable[key_index[i]];
+
+        //Permute from iclass format to standard format
+        loclass_permutekey_rev(key_sel, key_sel_p);
+        loclass_diversifyKey(csn, key_sel_p, div_key);
+    } else {
+        loclass_diversifyKey(csn, key, div_key);
+    }
+}

lib/loclass/optimized_cipher.h

@@ -0,0 +1,117 @@
+//-----------------------------------------------------------------------------
+// Borrowed initially from https://github.com/holiman/loclass
+// More recently from https://github.com/RfidResearchGroup/proxmark3
+// Copyright (C) 2014 Martin Holst Swende
+// Copyright (C) Proxmark3 contributors. See AUTHORS.md for details.
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// See LICENSE.txt for the text of the license.
+//-----------------------------------------------------------------------------
+// WARNING
+//
+// THIS CODE IS CREATED FOR EXPERIMENTATION AND EDUCATIONAL USE ONLY.
+//
+// USAGE OF THIS CODE IN OTHER WAYS MAY INFRINGE UPON THE INTELLECTUAL
+// PROPERTY OF OTHER PARTIES, SUCH AS INSIDE SECURE AND HID GLOBAL,
+// AND MAY EXPOSE YOU TO AN INFRINGEMENT ACTION FROM THOSE PARTIES.
+//
+// THIS CODE SHOULD NEVER BE USED TO INFRINGE PATENTS OR INTELLECTUAL PROPERTY RIGHTS.
+//-----------------------------------------------------------------------------
+// It is a reconstruction of the cipher engine used in iClass, and RFID techology.
+//
+// The implementation is based on the work performed by
+// Flavio D. Garcia, Gerhard de Koning Gans, Roel Verdult and
+// Milosch Meriac in the paper "Dismantling IClass".
+//-----------------------------------------------------------------------------
+#ifndef OPTIMIZED_CIPHER_H
+#define OPTIMIZED_CIPHER_H
+#include <stdlib.h>
+#include <string.h>
+#include <stdbool.h>
+#include <stdint.h>
+
+/**
+* Definition 1 (Cipher state). A cipher state of iClass s is an element of F 40/2
+* consisting of the following four components:
+*   1. the left register l = (l 0 . . . l 7 ) ∈ F 8/2 ;
+*   2. the right register r = (r 0 . . . r 7 ) ∈ F 8/2 ;
+*   3. the top register t = (t 0 . . . t 15 ) ∈ F 16/2 .
+*   4. the bottom register b = (b 0 . . . b 7 ) ∈ F 8/2 .
+**/
+typedef struct {
+    uint8_t l;
+    uint8_t r;
+    uint8_t b;
+    uint16_t t;
+} LoclassState_t;
+
+/** The reader MAC is MAC(key, CC * NR )
+ **/
+void loclass_opt_doReaderMAC(uint8_t* cc_nr_p, uint8_t* div_key_p, uint8_t mac[4]);
+
+void loclass_opt_doReaderMAC_2(
+    LoclassState_t _init,
+    uint8_t* nr,
+    uint8_t mac[4],
+    const uint8_t* div_key_p);
+
+/**
+ * The tag MAC is MAC(key, CC * NR * 32x0))
+ */
+void loclass_opt_doTagMAC(uint8_t* cc_p, const uint8_t* div_key_p, uint8_t mac[4]);
+
+/**
+ * The tag MAC can be divided (both can, but no point in dividing the reader mac) into
+ * two functions, since the first 8 bytes are known, we can pre-calculate the state
+ * reached after feeding CC to the cipher.
+ * @param cc_p
+ * @param div_key_p
+ * @return the cipher state
+ */
+LoclassState_t loclass_opt_doTagMAC_1(uint8_t* cc_p, const uint8_t* div_key_p);
+/**
+ * The second part of the tag MAC calculation, since the CC is already calculated into the state,
+ * this function is fed only the NR, and internally feeds the remaining 32 0-bits to generate the tag
+ * MAC response.
+ * @param _init - precalculated cipher state
+ * @param nr - the reader challenge
+ * @param mac - where to store the MAC
+ * @param div_key_p - the key to use
+ */
+void loclass_opt_doTagMAC_2(
+    LoclassState_t _init,
+    uint8_t* nr,
+    uint8_t mac[4],
+    const uint8_t* div_key_p);
+
+/**
+ * The same as loclass_opt_doTagMAC_2, but calculates both the reader and tag MACs at the same time
+ * @param _init - precalculated cipher state
+ * @param nr - the reader challenge
+ * @param rmac - where to store the reader MAC
+ * @param tmac - where to store the tag MAC
+ * @param div_key_p - the key to use
+ */
+void loclass_opt_doBothMAC_2(
+    LoclassState_t _init,
+    uint8_t* nr,
+    uint8_t rmac[4],
+    uint8_t tmac[4],
+    const uint8_t* div_key_p);
+
+void loclass_doMAC_N(uint8_t* in_p, uint8_t in_size, uint8_t* div_key_p, uint8_t mac[4]);
+void loclass_iclass_calc_div_key(
+    const uint8_t* csn,
+    const uint8_t* key,
+    uint8_t* div_key,
+    bool elite);
+#endif // OPTIMIZED_CIPHER_H

lib/loclass/optimized_cipherutils.c

@@ -0,0 +1,136 @@
+//-----------------------------------------------------------------------------
+// Borrowed initially from https://github.com/holiman/loclass
+// Copyright (C) 2014 Martin Holst Swende
+// Copyright (C) Proxmark3 contributors. See AUTHORS.md for details.
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// See LICENSE.txt for the text of the license.
+//-----------------------------------------------------------------------------
+// WARNING
+//
+// THIS CODE IS CREATED FOR EXPERIMENTATION AND EDUCATIONAL USE ONLY.
+//
+// USAGE OF THIS CODE IN OTHER WAYS MAY INFRINGE UPON THE INTELLECTUAL
+// PROPERTY OF OTHER PARTIES, SUCH AS INSIDE SECURE AND HID GLOBAL,
+// AND MAY EXPOSE YOU TO AN INFRINGEMENT ACTION FROM THOSE PARTIES.
+//
+// THIS CODE SHOULD NEVER BE USED TO INFRINGE PATENTS OR INTELLECTUAL PROPERTY RIGHTS.
+//-----------------------------------------------------------------------------
+// It is a reconstruction of the cipher engine used in iClass, and RFID techology.
+//
+// The implementation is based on the work performed by
+// Flavio D. Garcia, Gerhard de Koning Gans, Roel Verdult and
+// Milosch Meriac in the paper "Dismantling IClass".
+//-----------------------------------------------------------------------------
+#include "optimized_cipherutils.h"
+#include <stdint.h>
+
+/**
+ *
+ * @brief Return and remove the first bit (x0) in the stream : <x0 x1 x2 x3 ... xn >
+ * @param stream
+ * @return
+ */
+bool loclass_headBit(LoclassBitstreamIn_t* stream) {
+    int bytepos = stream->position >> 3; // divide by 8
+    int bitpos = (stream->position++) & 7; // mask out 00000111
+    return (*(stream->buffer + bytepos) >> (7 - bitpos)) & 1;
+}
+/**
+ * @brief Return and remove the last bit (xn) in the stream: <x0 x1 x2 ... xn>
+ * @param stream
+ * @return
+ */
+bool loclass_tailBit(LoclassBitstreamIn_t* stream) {
+    int bitpos = stream->numbits - 1 - (stream->position++);
+
+    int bytepos = bitpos >> 3;
+    bitpos &= 7;
+    return (*(stream->buffer + bytepos) >> (7 - bitpos)) & 1;
+}
+/**
+ * @brief Pushes bit onto the stream
+ * @param stream
+ * @param bit
+ */
+void loclass_pushBit(LoclassBitstreamOut_t* stream, bool bit) {
+    int bytepos = stream->position >> 3; // divide by 8
+    int bitpos = stream->position & 7;
+    *(stream->buffer + bytepos) |= (bit) << (7 - bitpos);
+    stream->position++;
+    stream->numbits++;
+}
+
+/**
+ * @brief Pushes the lower six bits onto the stream
+ * as b0 b1 b2 b3 b4 b5 b6
+ * @param stream
+ * @param bits
+ */
+void loclass_push6bits(LoclassBitstreamOut_t* stream, uint8_t bits) {
+    loclass_pushBit(stream, bits & 0x20);
+    loclass_pushBit(stream, bits & 0x10);
+    loclass_pushBit(stream, bits & 0x08);
+    loclass_pushBit(stream, bits & 0x04);
+    loclass_pushBit(stream, bits & 0x02);
+    loclass_pushBit(stream, bits & 0x01);
+}
+
+/**
+ * @brief loclass_bitsLeft
+ * @param stream
+ * @return number of bits left in stream
+ */
+int loclass_bitsLeft(LoclassBitstreamIn_t* stream) {
+    return stream->numbits - stream->position;
+}
+/**
+ * @brief numBits
+ * @param stream
+ * @return Number of bits stored in stream
+ */
+void loclass_x_num_to_bytes(uint64_t n, size_t len, uint8_t* dest) {
+    while(len--) {
+        dest[len] = (uint8_t)n;
+        n >>= 8;
+    }
+}
+
+uint64_t loclass_x_bytes_to_num(uint8_t* src, size_t len) {
+    uint64_t num = 0;
+    while(len--) {
+        num = (num << 8) | (*src);
+        src++;
+    }
+    return num;
+}
+
+uint8_t loclass_reversebytes(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 loclass_reverse_arraybytes(uint8_t* arr, size_t len) {
+    uint8_t i;
+    for(i = 0; i < len; i++) {
+        arr[i] = loclass_reversebytes(arr[i]);
+    }
+}
+
+void loclass_reverse_arraycopy(uint8_t* arr, uint8_t* dest, size_t len) {
+    uint8_t i;
+    for(i = 0; i < len; i++) {
+        dest[i] = loclass_reversebytes(arr[i]);
+    }
+}

lib/loclass/optimized_cipherutils.h

@@ -0,0 +1,64 @@
+//-----------------------------------------------------------------------------
+// Borrowed initially from https://github.com/holiman/loclass
+// More recently from https://github.com/RfidResearchGroup/proxmark3
+// Copyright (C) 2014 Martin Holst Swende
+// Copyright (C) Proxmark3 contributors. See AUTHORS.md for details.
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// See LICENSE.txt for the text of the license.
+//-----------------------------------------------------------------------------
+// WARNING
+//
+// THIS CODE IS CREATED FOR EXPERIMENTATION AND EDUCATIONAL USE ONLY.
+//
+// USAGE OF THIS CODE IN OTHER WAYS MAY INFRINGE UPON THE INTELLECTUAL
+// PROPERTY OF OTHER PARTIES, SUCH AS INSIDE SECURE AND HID GLOBAL,
+// AND MAY EXPOSE YOU TO AN INFRINGEMENT ACTION FROM THOSE PARTIES.
+//
+// THIS CODE SHOULD NEVER BE USED TO INFRINGE PATENTS OR INTELLECTUAL PROPERTY RIGHTS.
+//-----------------------------------------------------------------------------
+// It is a reconstruction of the cipher engine used in iClass, and RFID techology.
+//
+// The implementation is based on the work performed by
+// Flavio D. Garcia, Gerhard de Koning Gans, Roel Verdult and
+// Milosch Meriac in the paper "Dismantling IClass".
+//-----------------------------------------------------------------------------
+#ifndef CIPHERUTILS_H
+#define CIPHERUTILS_H
+#include <stdint.h>
+#include <stdbool.h>
+#include <stdlib.h>
+
+typedef struct {
+    uint8_t* buffer;
+    uint8_t numbits;
+    uint8_t position;
+} LoclassBitstreamIn_t;
+
+typedef struct {
+    uint8_t* buffer;
+    uint8_t numbits;
+    uint8_t position;
+} LoclassBitstreamOut_t;
+
+bool loclass_headBit(LoclassBitstreamIn_t* stream);
+bool loclass_tailBit(LoclassBitstreamIn_t* stream);
+void loclass_pushBit(LoclassBitstreamOut_t* stream, bool bit);
+int loclass_bitsLeft(LoclassBitstreamIn_t* stream);
+
+void loclass_push6bits(LoclassBitstreamOut_t* stream, uint8_t bits);
+void loclass_x_num_to_bytes(uint64_t n, size_t len, uint8_t* dest);
+uint64_t loclass_x_bytes_to_num(uint8_t* src, size_t len);
+uint8_t loclass_reversebytes(uint8_t b);
+void loclass_reverse_arraybytes(uint8_t* arr, size_t len);
+void loclass_reverse_arraycopy(uint8_t* arr, uint8_t* dest, size_t len);
+#endif // CIPHERUTILS_H

lib/loclass/optimized_elite.c

@@ -0,0 +1,232 @@
+//-----------------------------------------------------------------------------
+// Borrowed initially from https://github.com/holiman/loclass
+// Copyright (C) 2014 Martin Holst Swende
+// Copyright (C) Proxmark3 contributors. See AUTHORS.md for details.
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// See LICENSE.txt for the text of the license.
+//-----------------------------------------------------------------------------
+// WARNING
+//
+// THIS CODE IS CREATED FOR EXPERIMENTATION AND EDUCATIONAL USE ONLY.
+//
+// USAGE OF THIS CODE IN OTHER WAYS MAY INFRINGE UPON THE INTELLECTUAL
+// PROPERTY OF OTHER PARTIES, SUCH AS INSIDE SECURE AND HID GLOBAL,
+// AND MAY EXPOSE YOU TO AN INFRINGEMENT ACTION FROM THOSE PARTIES.
+//
+// THIS CODE SHOULD NEVER BE USED TO INFRINGE PATENTS OR INTELLECTUAL PROPERTY RIGHTS.
+//-----------------------------------------------------------------------------
+// It is a reconstruction of the cipher engine used in iClass, and RFID techology.
+//
+// The implementation is based on the work performed by
+// Flavio D. Garcia, Gerhard de Koning Gans, Roel Verdult and
+// Milosch Meriac in the paper "Dismantling IClass".
+//-----------------------------------------------------------------------------
+#include "optimized_elite.h"
+
+#include <stdint.h>
+#include <stdbool.h>
+#include <string.h>
+#include <mbedtls/des.h>
+#include "optimized_ikeys.h"
+
+/**
+ * @brief Permutes a key from standard NIST format to Iclass specific format
+ *  from http://www.proxmark.org/forum/viewtopic.php?pid=11220#p11220
+ *
+ *  If you loclass_permute [6c 8d 44 f9 2a 2d 01 bf]  you get  [8a 0d b9 88 bb a7 90 ea]  as shown below.
+ *
+ *  1 0 1 1 1 1 1 1  bf
+ *  0 0 0 0 0 0 0 1  01
+ *  0 0 1 0 1 1 0 1  2d
+ *  0 0 1 0 1 0 1 0  2a
+ *  1 1 1 1 1 0 0 1  f9
+ *  0 1 0 0 0 1 0 0  44
+ *  1 0 0 0 1 1 0 1  8d
+ *  0 1 1 0 1 1 0 0  6c
+ *
+ *  8 0 b 8 b a 9 e
+ *  a d 9 8 b 7 0 a
+ *
+ * @param key
+ * @param dest
+ */
+void loclass_permutekey(const uint8_t key[8], uint8_t dest[8]) {
+    int i;
+    for(i = 0; i < 8; i++) {
+        dest[i] = (((key[7] & (0x80 >> i)) >> (7 - i)) << 7) |
+                  (((key[6] & (0x80 >> i)) >> (7 - i)) << 6) |
+                  (((key[5] & (0x80 >> i)) >> (7 - i)) << 5) |
+                  (((key[4] & (0x80 >> i)) >> (7 - i)) << 4) |
+                  (((key[3] & (0x80 >> i)) >> (7 - i)) << 3) |
+                  (((key[2] & (0x80 >> i)) >> (7 - i)) << 2) |
+                  (((key[1] & (0x80 >> i)) >> (7 - i)) << 1) |
+                  (((key[0] & (0x80 >> i)) >> (7 - i)) << 0);
+    }
+}
+/**
+ * Permutes  a key from iclass specific format to NIST format
+ * @brief loclass_permutekey_rev
+ * @param key
+ * @param dest
+ */
+void loclass_permutekey_rev(const uint8_t key[8], uint8_t dest[8]) {
+    int i;
+    for(i = 0; i < 8; i++) {
+        dest[7 - i] = (((key[0] & (0x80 >> i)) >> (7 - i)) << 7) |
+                      (((key[1] & (0x80 >> i)) >> (7 - i)) << 6) |
+                      (((key[2] & (0x80 >> i)) >> (7 - i)) << 5) |
+                      (((key[3] & (0x80 >> i)) >> (7 - i)) << 4) |
+                      (((key[4] & (0x80 >> i)) >> (7 - i)) << 3) |
+                      (((key[5] & (0x80 >> i)) >> (7 - i)) << 2) |
+                      (((key[6] & (0x80 >> i)) >> (7 - i)) << 1) |
+                      (((key[7] & (0x80 >> i)) >> (7 - i)) << 0);
+    }
+}
+
+/**
+ * Helper function for loclass_hash1
+ * @brief loclass_rr
+ * @param val
+ * @return
+ */
+static uint8_t loclass_rr(uint8_t val) {
+    return val >> 1 | ((val & 1) << 7);
+}
+
+/**
+ * Helper function for loclass_hash1
+ * @brief rl
+ * @param val
+ * @return
+ */
+static uint8_t loclass_rl(uint8_t val) {
+    return val << 1 | ((val & 0x80) >> 7);
+}
+
+/**
+ * Helper function for loclass_hash1
+ * @brief loclass_swap
+ * @param val
+ * @return
+ */
+static uint8_t loclass_swap(uint8_t val) {
+    return ((val >> 4) & 0xFF) | ((val & 0xFF) << 4);
+}
+
+/**
+ * Hash1 takes CSN as input, and determines what bytes in the keytable will be used
+ * when constructing the K_sel.
+ * @param csn the CSN used
+ * @param k output
+ */
+void loclass_hash1(const uint8_t csn[], uint8_t k[]) {
+    k[0] = csn[0] ^ csn[1] ^ csn[2] ^ csn[3] ^ csn[4] ^ csn[5] ^ csn[6] ^ csn[7];
+    k[1] = csn[0] + csn[1] + csn[2] + csn[3] + csn[4] + csn[5] + csn[6] + csn[7];
+    k[2] = loclass_rr(loclass_swap(csn[2] + k[1]));
+    k[3] = loclass_rl(loclass_swap(csn[3] + k[0]));
+    k[4] = ~loclass_rr(csn[4] + k[2]) + 1;
+    k[5] = ~loclass_rl(csn[5] + k[3]) + 1;
+    k[6] = loclass_rr(csn[6] + (k[4] ^ 0x3c));
+    k[7] = loclass_rl(csn[7] + (k[5] ^ 0xc3));
+
+    k[7] &= 0x7F;
+    k[6] &= 0x7F;
+    k[5] &= 0x7F;
+    k[4] &= 0x7F;
+    k[3] &= 0x7F;
+    k[2] &= 0x7F;
+    k[1] &= 0x7F;
+    k[0] &= 0x7F;
+}
+/**
+Definition 14. Define the rotate key function loclass_rk : (F 82 ) 8 × N → (F 82 ) 8 as
+loclass_rk(x [0] . . . x [7] , 0) = x [0] . . . x [7]
+loclass_rk(x [0] . . . x [7] , n + 1) = loclass_rk(loclass_rl(x [0] ) . . . loclass_rl(x [7] ), n)
+**/
+static void loclass_rk(const uint8_t* key, uint8_t n, uint8_t* outp_key) {
+    memcpy(outp_key, key, 8);
+    uint8_t j;
+    while(n-- > 0) {
+        for(j = 0; j < 8; j++) outp_key[j] = loclass_rl(outp_key[j]);
+    }
+    return;
+}
+
+static mbedtls_des_context loclass_ctx_enc;
+static mbedtls_des_context loclass_ctx_dec;
+
+static void loclass_desdecrypt_iclass(uint8_t* iclass_key, uint8_t* input, uint8_t* output) {
+    uint8_t key_std_format[8] = {0};
+    loclass_permutekey_rev(iclass_key, key_std_format);
+    mbedtls_des_setkey_dec(&loclass_ctx_dec, key_std_format);
+    mbedtls_des_crypt_ecb(&loclass_ctx_dec, input, output);
+}
+
+static void loclass_desencrypt_iclass(const uint8_t* iclass_key, uint8_t* input, uint8_t* output) {
+    uint8_t key_std_format[8] = {0};
+    loclass_permutekey_rev(iclass_key, key_std_format);
+    mbedtls_des_setkey_enc(&loclass_ctx_enc, key_std_format);
+    mbedtls_des_crypt_ecb(&loclass_ctx_enc, input, output);
+}
+
+/**
+ * @brief Insert uint8_t[8] custom master key to calculate hash2 and return key_select.
+ * @param key unpermuted custom key
+ * @param loclass_hash1 loclass_hash1
+ * @param key_sel output key_sel=h[loclass_hash1[i]]
+ */
+void loclass_hash2(const uint8_t* key64, uint8_t* outp_keytable) {
+    /**
+     *Expected:
+     * High Security Key Table
+
+    00  F1 35 59 A1 0D 5A 26 7F 18 60 0B 96 8A C0 25 C1
+    10  BF A1 3B B0 FF 85 28 75 F2 1F C6 8F 0E 74 8F 21
+    20  14 7A 55 16 C8 A9 7D B3 13 0C 5D C9 31 8D A9 B2
+    30  A3 56 83 0F 55 7E DE 45 71 21 D2 6D C1 57 1C 9C
+    40  78 2F 64 51 42 7B 64 30 FA 26 51 76 D3 E0 FB B6
+    50  31 9F BF 2F 7E 4F 94 B4 BD 4F 75 91 E3 1B EB 42
+    60  3F 88 6F B8 6C 2C 93 0D 69 2C D5 20 3C C1 61 95
+    70  43 08 A0 2F FE B3 26 D7 98 0B 34 7B 47 70 A0 AB
+
+    **** The 64-bit HS Custom Key Value = 5B7C62C491C11B39 ******/
+    uint8_t key64_negated[8] = {0};
+    uint8_t z[8][8] = {{0}, {0}};
+    uint8_t temp_output[8] = {0};
+
+    //calculate complement of key
+    int i;
+    for(i = 0; i < 8; i++) key64_negated[i] = ~key64[i];
+
+    // Once again, key is on iclass-format
+    loclass_desencrypt_iclass(key64, key64_negated, z[0]);
+
+    uint8_t y[8][8] = {{0}, {0}};
+
+    // y[0]=DES_dec(z[0],~key)
+    // Once again, key is on iclass-format
+    loclass_desdecrypt_iclass(z[0], key64_negated, y[0]);
+
+    for(i = 1; i < 8; i++) {
+        loclass_rk(key64, i, temp_output);
+        loclass_desdecrypt_iclass(temp_output, z[i - 1], z[i]);
+        loclass_desencrypt_iclass(temp_output, y[i - 1], y[i]);
+    }
+
+    if(outp_keytable != NULL) {
+        for(i = 0; i < 8; i++) {
+            memcpy(outp_keytable + i * 16, y[i], 8);
+            memcpy(outp_keytable + 8 + i * 16, z[i], 8);
+        }
+    }
+}

lib/loclass/optimized_elite.h

@@ -0,0 +1,58 @@
+//-----------------------------------------------------------------------------
+// Borrowed initially from https://github.com/holiman/loclass
+// More recently from https://github.com/RfidResearchGroup/proxmark3
+// Copyright (C) 2014 Martin Holst Swende
+// Copyright (C) Proxmark3 contributors. See AUTHORS.md for details.
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// See LICENSE.txt for the text of the license.
+//-----------------------------------------------------------------------------
+// WARNING
+//
+// THIS CODE IS CREATED FOR EXPERIMENTATION AND EDUCATIONAL USE ONLY.
+//
+// USAGE OF THIS CODE IN OTHER WAYS MAY INFRINGE UPON THE INTELLECTUAL
+// PROPERTY OF OTHER PARTIES, SUCH AS INSIDE SECURE AND HID GLOBAL,
+// AND MAY EXPOSE YOU TO AN INFRINGEMENT ACTION FROM THOSE PARTIES.
+//
+// THIS CODE SHOULD NEVER BE USED TO INFRINGE PATENTS OR INTELLECTUAL PROPERTY RIGHTS.
+//-----------------------------------------------------------------------------
+// It is a reconstruction of the cipher engine used in iClass, and RFID techology.
+//
+// The implementation is based on the work performed by
+// Flavio D. Garcia, Gerhard de Koning Gans, Roel Verdult and
+// Milosch Meriac in the paper "Dismantling IClass".
+//-----------------------------------------------------------------------------
+#ifndef ELITE_CRACK_H
+#define ELITE_CRACK_H
+
+#include <stdint.h>
+#include <stdlib.h>
+
+void loclass_permutekey(const uint8_t key[8], uint8_t dest[8]);
+/**
+ * Permutes  a key from iclass specific format to NIST format
+ * @brief loclass_permutekey_rev
+ * @param key
+ * @param dest
+ */
+void loclass_permutekey_rev(const uint8_t key[8], uint8_t dest[8]);
+/**
+ * Hash1 takes CSN as input, and determines what bytes in the keytable will be used
+ * when constructing the K_sel.
+ * @param csn the CSN used
+ * @param k output
+ */
+void loclass_hash1(const uint8_t* csn, uint8_t* k);
+void loclass_hash2(const uint8_t* key64, uint8_t* outp_keytable);
+
+#endif

lib/loclass/optimized_ikeys.c

@@ -0,0 +1,320 @@
+//-----------------------------------------------------------------------------
+// Borrowed initially from https://github.com/holiman/loclass
+// Copyright (C) 2014 Martin Holst Swende
+// Copyright (C) Proxmark3 contributors. See AUTHORS.md for details.
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// See LICENSE.txt for the text of the license.
+//-----------------------------------------------------------------------------
+// WARNING
+//
+// THIS CODE IS CREATED FOR EXPERIMENTATION AND EDUCATIONAL USE ONLY.
+//
+// USAGE OF THIS CODE IN OTHER WAYS MAY INFRINGE UPON THE INTELLECTUAL
+// PROPERTY OF OTHER PARTIES, SUCH AS INSIDE SECURE AND HID GLOBAL,
+// AND MAY EXPOSE YOU TO AN INFRINGEMENT ACTION FROM THOSE PARTIES.
+//
+// THIS CODE SHOULD NEVER BE USED TO INFRINGE PATENTS OR INTELLECTUAL PROPERTY RIGHTS.
+//-----------------------------------------------------------------------------
+// It is a reconstruction of the cipher engine used in iClass, and RFID techology.
+//
+// The implementation is based on the work performed by
+// Flavio D. Garcia, Gerhard de Koning Gans, Roel Verdult and
+// Milosch Meriac in the paper "Dismantling IClass".
+//-----------------------------------------------------------------------------
+
+/**
+From "Dismantling iclass":
+    This section describes in detail the built-in key diversification algorithm of iClass.
+    Besides the obvious purpose of deriving a card key from a master key, this
+    algorithm intends to circumvent weaknesses in the cipher by preventing the
+    usage of certain ‘weak’ keys. In order to compute a diversified key, the iClass
+    reader first encrypts the card identity id with the master key K, using single
+    DES. The resulting ciphertext is then input to a function called loclass_hash0 which
+    outputs the diversified key k.
+
+    k = loclass_hash0(DES enc (id, K))
+
+    Here the DES encryption of id with master key K outputs a cryptogram c
+    of 64 bits. These 64 bits are divided as c = x, y, z [0] , . . . , z [7] ∈ F 82 × F 82 × (F 62 ) 8
+    which is used as input to the loclass_hash0 function. This function introduces some
+    obfuscation by performing a number of permutations, complement and modulo
+    operations, see Figure 2.5. Besides that, it checks for and removes patterns like
+    similar key bytes, which could produce a strong bias in the cipher. Finally, the
+    output of loclass_hash0 is the diversified card key k = k [0] , . . . , k [7] ∈ (F 82 ) 8 .
+
+**/
+#include "optimized_ikeys.h"
+
+#include <stdint.h>
+#include <stdbool.h>
+#include <inttypes.h>
+#include <mbedtls/des.h>
+#include "optimized_cipherutils.h"
+
+static const uint8_t loclass_pi[35] = {0x0F, 0x17, 0x1B, 0x1D, 0x1E, 0x27, 0x2B, 0x2D, 0x2E,
+                                       0x33, 0x35, 0x39, 0x36, 0x3A, 0x3C, 0x47, 0x4B, 0x4D,
+                                       0x4E, 0x53, 0x55, 0x56, 0x59, 0x5A, 0x5C, 0x63, 0x65,
+                                       0x66, 0x69, 0x6A, 0x6C, 0x71, 0x72, 0x74, 0x78};
+
+/**
+ * @brief The key diversification algorithm uses 6-bit bytes.
+ * This implementation uses 64 bit uint to pack seven of them into one
+ * variable. When they are there, they are placed as follows:
+ * XXXX XXXX N0 .... N7, occupying the last 48 bits.
+ *
+ * This function picks out one from such a collection
+ * @param all
+ * @param n bitnumber
+ * @return
+ */
+static uint8_t loclass_getSixBitByte(uint64_t c, int n) {
+    return (c >> (42 - 6 * n)) & 0x3F;
+}
+
+/**
+ * @brief Puts back a six-bit 'byte' into a uint64_t.
+ * @param c buffer
+ * @param z the value to place there
+ * @param n bitnumber.
+ */
+static void loclass_pushbackSixBitByte(uint64_t* c, uint8_t z, int n) {
+    //0x XXXX YYYY ZZZZ ZZZZ ZZZZ
+    //             ^z0         ^z7
+    //z0:  1111 1100 0000 0000
+
+    uint64_t masked = z & 0x3F;
+    uint64_t eraser = 0x3F;
+    masked <<= 42 - 6 * n;
+    eraser <<= 42 - 6 * n;
+
+    //masked <<= 6*n;
+    //eraser <<= 6*n;
+
+    eraser = ~eraser;
+    (*c) &= eraser;
+    (*c) |= masked;
+}
+/**
+ * @brief Swaps the z-values.
+ * If the input value has format XYZ0Z1...Z7, the output will have the format
+ * XYZ7Z6...Z0 instead
+ * @param c
+ * @return
+ */
+static uint64_t loclass_swapZvalues(uint64_t c) {
+    uint64_t newz = 0;
+    loclass_pushbackSixBitByte(&newz, loclass_getSixBitByte(c, 0), 7);
+    loclass_pushbackSixBitByte(&newz, loclass_getSixBitByte(c, 1), 6);
+    loclass_pushbackSixBitByte(&newz, loclass_getSixBitByte(c, 2), 5);
+    loclass_pushbackSixBitByte(&newz, loclass_getSixBitByte(c, 3), 4);
+    loclass_pushbackSixBitByte(&newz, loclass_getSixBitByte(c, 4), 3);
+    loclass_pushbackSixBitByte(&newz, loclass_getSixBitByte(c, 5), 2);
+    loclass_pushbackSixBitByte(&newz, loclass_getSixBitByte(c, 6), 1);
+    loclass_pushbackSixBitByte(&newz, loclass_getSixBitByte(c, 7), 0);
+    newz |= (c & 0xFFFF000000000000);
+    return newz;
+}
+
+/**
+* @return 4 six-bit bytes chunked into a uint64_t,as 00..00a0a1a2a3
+*/
+static uint64_t loclass_ck(int i, int j, uint64_t z) {
+    if(i == 1 && j == -1) {
+        // loclass_ck(1, −1, z [0] . . . z [3] ) = z [0] . . . z [3]
+        return z;
+    } else if(j == -1) {
+        // loclass_ck(i, −1, z [0] . . . z [3] ) = loclass_ck(i − 1, i − 2, z [0] . . . z [3] )
+        return loclass_ck(i - 1, i - 2, z);
+    }
+
+    if(loclass_getSixBitByte(z, i) == loclass_getSixBitByte(z, j)) {
+        //loclass_ck(i, j − 1, z [0] . . . z [i] ← j . . . z [3] )
+        uint64_t newz = 0;
+        int c;
+        for(c = 0; c < 4; c++) {
+            uint8_t val = loclass_getSixBitByte(z, c);
+            if(c == i)
+                loclass_pushbackSixBitByte(&newz, j, c);
+            else
+                loclass_pushbackSixBitByte(&newz, val, c);
+        }
+        return loclass_ck(i, j - 1, newz);
+    } else {
+        return loclass_ck(i, j - 1, z);
+    }
+}
+/**
+
+    Definition 8.
+    Let the function check : (F 62 ) 8 → (F 62 ) 8 be defined as
+    check(z [0] . . . z [7] ) = loclass_ck(3, 2, z [0] . . . z [3] ) · loclass_ck(3, 2, z [4] . . . z [7] )
+
+    where loclass_ck : N × N × (F 62 ) 4 → (F 62 ) 4 is defined as
+
+        loclass_ck(1, −1, z [0] . . . z [3] ) = z [0] . . . z [3]
+        loclass_ck(i, −1, z [0] . . . z [3] ) = loclass_ck(i − 1, i − 2, z [0] . . . z [3] )
+        loclass_ck(i, j, z [0] . . . z [3] ) =
+        loclass_ck(i, j − 1, z [0] . . . z [i] ← j . . . z [3] ),  if z [i] = z [j] ;
+        loclass_ck(i, j − 1, z [0] . . . z [3] ), otherwise
+
+    otherwise.
+**/
+
+static uint64_t loclass_check(uint64_t z) {
+    //These 64 bits are divided as c = x, y, z [0] , . . . , z [7]
+
+    // loclass_ck(3, 2, z [0] . . . z [3] )
+    uint64_t ck1 = loclass_ck(3, 2, z);
+
+    // loclass_ck(3, 2, z [4] . . . z [7] )
+    uint64_t ck2 = loclass_ck(3, 2, z << 24);
+
+    //The loclass_ck function will place the values
+    // in the middle of z.
+    ck1 &= 0x00000000FFFFFF000000;
+    ck2 &= 0x00000000FFFFFF000000;
+
+    return ck1 | ck2 >> 24;
+}
+
+static void loclass_permute(
+    LoclassBitstreamIn_t* p_in,
+    uint64_t z,
+    int l,
+    int r,
+    LoclassBitstreamOut_t* out) {
+    if(loclass_bitsLeft(p_in) == 0) return;
+
+    bool pn = loclass_tailBit(p_in);
+    if(pn) { // pn = 1
+        uint8_t zl = loclass_getSixBitByte(z, l);
+
+        loclass_push6bits(out, zl + 1);
+        loclass_permute(p_in, z, l + 1, r, out);
+    } else { // otherwise
+        uint8_t zr = loclass_getSixBitByte(z, r);
+
+        loclass_push6bits(out, zr);
+        loclass_permute(p_in, z, l, r + 1, out);
+    }
+}
+
+/**
+ * @brief
+ *Definition 11. Let the function loclass_hash0 : F 82 × F 82 × (F 62 ) 8 → (F 82 ) 8 be defined as
+ *  loclass_hash0(x, y, z [0] . . . z [7] ) = k [0] . . . k [7] where
+ * z'[i] = (z[i] mod (63-i)) + i      i =  0...3
+ * z'[i+4] = (z[i+4] mod (64-i)) + i  i =  0...3
+ * ẑ = check(z');
+ * @param c
+ * @param k this is where the diversified key is put (should be 8 bytes)
+ * @return
+ */
+void loclass_hash0(uint64_t c, uint8_t k[8]) {
+    c = loclass_swapZvalues(c);
+
+    //These 64 bits are divided as c = x, y, z [0] , . . . , z [7]
+    // x = 8 bits
+    // y = 8 bits
+    // z0-z7 6 bits each : 48 bits
+    uint8_t x = (c & 0xFF00000000000000) >> 56;
+    uint8_t y = (c & 0x00FF000000000000) >> 48;
+    uint64_t zP = 0;
+
+    for(int n = 0; n < 4; n++) {
+        uint8_t zn = loclass_getSixBitByte(c, n);
+        uint8_t zn4 = loclass_getSixBitByte(c, n + 4);
+        uint8_t _zn = (zn % (63 - n)) + n;
+        uint8_t _zn4 = (zn4 % (64 - n)) + n;
+        loclass_pushbackSixBitByte(&zP, _zn, n);
+        loclass_pushbackSixBitByte(&zP, _zn4, n + 4);
+    }
+
+    uint64_t zCaret = loclass_check(zP);
+    uint8_t p = loclass_pi[x % 35];
+
+    if(x & 1) //Check if x7 is 1
+        p = ~p;
+
+    LoclassBitstreamIn_t p_in = {&p, 8, 0};
+    uint8_t outbuffer[] = {0, 0, 0, 0, 0, 0, 0, 0};
+    LoclassBitstreamOut_t out = {outbuffer, 0, 0};
+    loclass_permute(&p_in, zCaret, 0, 4, &out); //returns 48 bits? or 6 8-bytes
+
+    //Out is now a buffer containing six-bit bytes, should be 48 bits
+    // if all went well
+    //Shift z-values down onto the lower segment
+
+    uint64_t zTilde = loclass_x_bytes_to_num(outbuffer, sizeof(outbuffer));
+
+    zTilde >>= 16;
+
+    for(int i = 0; i < 8; i++) {
+        // the key on index i is first a bit from y
+        // then six bits from z,
+        // then a bit from p
+
+        // Init with zeroes
+        k[i] = 0;
+        // First, place yi leftmost in k
+        //k[i] |= (y  << i) & 0x80 ;
+
+        // First, place y(7-i) leftmost in k
+        k[i] |= (y << (7 - i)) & 0x80;
+
+        uint8_t zTilde_i = loclass_getSixBitByte(zTilde, i);
+        // zTildeI is now on the form 00XXXXXX
+        // with one leftshift, it'll be
+        // 0XXXXXX0
+        // So after leftshift, we can OR it into k
+        // However, when doing complement, we need to
+        // again MASK 0XXXXXX0 (0x7E)
+        zTilde_i <<= 1;
+
+        //Finally, add bit from p or p-mod
+        //Shift bit i into rightmost location (mask only after complement)
+        uint8_t p_i = p >> i & 0x1;
+
+        if(k[i]) { // yi = 1
+            k[i] |= ~zTilde_i & 0x7E;
+            k[i] |= p_i & 1;
+            k[i] += 1;
+
+        } else { // otherwise
+            k[i] |= zTilde_i & 0x7E;
+            k[i] |= (~p_i) & 1;
+        }
+    }
+}
+/**
+ * @brief Performs Elite-class key diversification
+ * @param csn
+ * @param key
+ * @param div_key
+ */
+void loclass_diversifyKey(const uint8_t* csn, const uint8_t* key, uint8_t* div_key) {
+    mbedtls_des_context loclass_ctx_enc;
+
+    // Prepare the DES key
+    mbedtls_des_setkey_enc(&loclass_ctx_enc, key);
+
+    uint8_t crypted_csn[8] = {0};
+
+    // Calculate DES(CSN, KEY)
+    mbedtls_des_crypt_ecb(&loclass_ctx_enc, csn, crypted_csn);
+
+    //Calculate HASH0(DES))
+    uint64_t c_csn = loclass_x_bytes_to_num(crypted_csn, sizeof(crypted_csn));
+
+    loclass_hash0(c_csn, div_key);
+}

lib/loclass/optimized_ikeys.h

@@ -0,0 +1,66 @@
+//-----------------------------------------------------------------------------
+// Borrowed initially from https://github.com/holiman/loclass
+// More recently from https://github.com/RfidResearchGroup/proxmark3
+// Copyright (C) 2014 Martin Holst Swende
+// Copyright (C) Proxmark3 contributors. See AUTHORS.md for details.
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// See LICENSE.txt for the text of the license.
+//-----------------------------------------------------------------------------
+// WARNING
+//
+// THIS CODE IS CREATED FOR EXPERIMENTATION AND EDUCATIONAL USE ONLY.
+//
+// USAGE OF THIS CODE IN OTHER WAYS MAY INFRINGE UPON THE INTELLECTUAL
+// PROPERTY OF OTHER PARTIES, SUCH AS INSIDE SECURE AND HID GLOBAL,
+// AND MAY EXPOSE YOU TO AN INFRINGEMENT ACTION FROM THOSE PARTIES.
+//
+// THIS CODE SHOULD NEVER BE USED TO INFRINGE PATENTS OR INTELLECTUAL PROPERTY RIGHTS.
+//-----------------------------------------------------------------------------
+// It is a reconstruction of the cipher engine used in iClass, and RFID techology.
+//
+// The implementation is based on the work performed by
+// Flavio D. Garcia, Gerhard de Koning Gans, Roel Verdult and
+// Milosch Meriac in the paper "Dismantling IClass".
+//-----------------------------------------------------------------------------
+#ifndef IKEYS_H
+#define IKEYS_H
+
+#include <inttypes.h>
+
+/**
+ * @brief
+ *Definition 11. Let the function loclass_hash0 : F 82 × F 82 × (F 62 ) 8 → (F 82 ) 8 be defined as
+ *  loclass_hash0(x, y, z [0] . . . z [7] ) = k [0] . . . k [7] where
+ * z'[i] = (z[i] mod (63-i)) + i        i =  0...3
+ * z'[i+4] = (z[i+4] mod (64-i)) + i    i =  0...3
+ * ẑ = check(z');
+ * @param c
+ * @param k this is where the diversified key is put (should be 8 bytes)
+ * @return
+ */
+void loclass_hash0(uint64_t c, uint8_t k[8]);
+/**
+ * @brief Performs Elite-class key diversification
+ * @param csn
+ * @param key
+ * @param div_key
+ */
+
+void loclass_diversifyKey(const uint8_t* csn, const uint8_t* key, uint8_t* div_key);
+/**
+ * @brief Permutes a key from standard NIST format to Iclass specific format
+ * @param key
+ * @param dest
+ */
+
+#endif // IKEYS_H