231 lines
9.5 KiB
C
231 lines
9.5 KiB
C
/*
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* COMP128 implementation
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*
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*
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* This code is inspired by original code from :
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* Marc Briceno <marc@scard.org>, Ian Goldberg <iang@cs.berkeley.edu>,
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* and David Wagner <daw@cs.berkeley.edu>
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*
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* But it has been fully rewritten from various PDFs found online describing
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* the algorithm because the licence of the code referenced above was unclear.
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* A comment snippet from the original code is included below, it describes
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* where the doc came from and how the algorithm was reverse engineered.
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*
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*
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* (C) 2009 by Sylvain Munaut <tnt@246tNt.com>
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*
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* All Rights Reserved
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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*/
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/*
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* --- SNIP ---
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*
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* This code derived from a leaked document from the GSM standards.
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* Some missing pieces were filled in by reverse-engineering a working SIM.
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* We have verified that this is the correct COMP128 algorithm.
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*
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* The first page of the document identifies it as
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* _Technical Information: GSM System Security Study_.
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* 10-1617-01, 10th June 1988.
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* The bottom of the title page is marked
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* Racal Research Ltd.
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* Worton Drive, Worton Grange Industrial Estate,
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* Reading, Berks. RG2 0SB, England.
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* Telephone: Reading (0734) 868601 Telex: 847152
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* The relevant bits are in Part I, Section 20 (pages 66--67). Enjoy!
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*
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* Note: There are three typos in the spec (discovered by
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* reverse-engineering).
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* First, "z = (2 * x[n] + x[n]) mod 2^(9-j)" should clearly read
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* "z = (2 * x[m] + x[n]) mod 2^(9-j)".
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* Second, the "k" loop in the "Form bits from bytes" section is severely
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* botched: the k index should run only from 0 to 3, and clearly the range
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* on "the (8-k)th bit of byte j" is also off (should be 0..7, not 1..8,
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* to be consistent with the subsequent section).
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* Third, SRES is taken from the first 8 nibbles of x[], not the last 8 as
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* claimed in the document. (And the document doesn't specify how Kc is
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* derived, but that was also easily discovered with reverse engineering.)
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* All of these typos have been corrected in the following code.
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*
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* --- /SNIP ---
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*/
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#include <string.h>
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#include <sys/types.h>
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/* The compression tables (just copied ...) */
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static const u_int8_t table_0[512] = {
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102, 177, 186, 162, 2, 156, 112, 75, 55, 25, 8, 12, 251, 193, 246, 188,
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109, 213, 151, 53, 42, 79, 191, 115, 233, 242, 164, 223, 209, 148, 108, 161,
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252, 37, 244, 47, 64, 211, 6, 237, 185, 160, 139, 113, 76, 138, 59, 70,
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67, 26, 13, 157, 63, 179, 221, 30, 214, 36, 166, 69, 152, 124, 207, 116,
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247, 194, 41, 84, 71, 1, 49, 14, 95, 35, 169, 21, 96, 78, 215, 225,
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182, 243, 28, 92, 201, 118, 4, 74, 248, 128, 17, 11, 146, 132, 245, 48,
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149, 90, 120, 39, 87, 230, 106, 232, 175, 19, 126, 190, 202, 141, 137, 176,
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250, 27, 101, 40, 219, 227, 58, 20, 51, 178, 98, 216, 140, 22, 32, 121,
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61, 103, 203, 72, 29, 110, 85, 212, 180, 204, 150, 183, 15, 66, 172, 196,
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56, 197, 158, 0, 100, 45, 153, 7, 144, 222, 163, 167, 60, 135, 210, 231,
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174, 165, 38, 249, 224, 34, 220, 229, 217, 208, 241, 68, 206, 189, 125, 255,
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239, 54, 168, 89, 123, 122, 73, 145, 117, 234, 143, 99, 129, 200, 192, 82,
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104, 170, 136, 235, 93, 81, 205, 173, 236, 94, 105, 52, 46, 228, 198, 5,
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57, 254, 97, 155, 142, 133, 199, 171, 187, 50, 65, 181, 127, 107, 147, 226,
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184, 218, 131, 33, 77, 86, 31, 44, 88, 62, 238, 18, 24, 43, 154, 23,
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80, 159, 134, 111, 9, 114, 3, 91, 16, 130, 83, 10, 195, 240, 253, 119,
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177, 102, 162, 186, 156, 2, 75, 112, 25, 55, 12, 8, 193, 251, 188, 246,
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213, 109, 53, 151, 79, 42, 115, 191, 242, 233, 223, 164, 148, 209, 161, 108,
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37, 252, 47, 244, 211, 64, 237, 6, 160, 185, 113, 139, 138, 76, 70, 59,
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26, 67, 157, 13, 179, 63, 30, 221, 36, 214, 69, 166, 124, 152, 116, 207,
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194, 247, 84, 41, 1, 71, 14, 49, 35, 95, 21, 169, 78, 96, 225, 215,
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243, 182, 92, 28, 118, 201, 74, 4, 128, 248, 11, 17, 132, 146, 48, 245,
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90, 149, 39, 120, 230, 87, 232, 106, 19, 175, 190, 126, 141, 202, 176, 137,
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27, 250, 40, 101, 227, 219, 20, 58, 178, 51, 216, 98, 22, 140, 121, 32,
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103, 61, 72, 203, 110, 29, 212, 85, 204, 180, 183, 150, 66, 15, 196, 172,
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197, 56, 0, 158, 45, 100, 7, 153, 222, 144, 167, 163, 135, 60, 231, 210,
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165, 174, 249, 38, 34, 224, 229, 220, 208, 217, 68, 241, 189, 206, 255, 125,
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54, 239, 89, 168, 122, 123, 145, 73, 234, 117, 99, 143, 200, 129, 82, 192,
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170, 104, 235, 136, 81, 93, 173, 205, 94, 236, 52, 105, 228, 46, 5, 198,
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254, 57, 155, 97, 133, 142, 171, 199, 50, 187, 181, 65, 107, 127, 226, 147,
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218, 184, 33, 131, 86, 77, 44, 31, 62, 88, 18, 238, 43, 24, 23, 154,
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159, 80, 111, 134, 114, 9, 91, 3, 130, 16, 10, 83, 240, 195, 119, 253,
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}, table_1[256] = {
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19, 11, 80, 114, 43, 1, 69, 94, 39, 18, 127, 117, 97, 3, 85, 43,
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27, 124, 70, 83, 47, 71, 63, 10, 47, 89, 79, 4, 14, 59, 11, 5,
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35, 107, 103, 68, 21, 86, 36, 91, 85, 126, 32, 50, 109, 94, 120, 6,
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53, 79, 28, 45, 99, 95, 41, 34, 88, 68, 93, 55, 110, 125, 105, 20,
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90, 80, 76, 96, 23, 60, 89, 64, 121, 56, 14, 74, 101, 8, 19, 78,
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76, 66, 104, 46, 111, 50, 32, 3, 39, 0, 58, 25, 92, 22, 18, 51,
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57, 65, 119, 116, 22, 109, 7, 86, 59, 93, 62, 110, 78, 99, 77, 67,
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12, 113, 87, 98, 102, 5, 88, 33, 38, 56, 23, 8, 75, 45, 13, 75,
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95, 63, 28, 49, 123, 120, 20, 112, 44, 30, 15, 98, 106, 2, 103, 29,
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82, 107, 42, 124, 24, 30, 41, 16, 108, 100, 117, 40, 73, 40, 7, 114,
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82, 115, 36, 112, 12, 102, 100, 84, 92, 48, 72, 97, 9, 54, 55, 74,
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113, 123, 17, 26, 53, 58, 4, 9, 69, 122, 21, 118, 42, 60, 27, 73,
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118, 125, 34, 15, 65, 115, 84, 64, 62, 81, 70, 1, 24, 111, 121, 83,
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104, 81, 49, 127, 48, 105, 31, 10, 6, 91, 87, 37, 16, 54, 116, 126,
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31, 38, 13, 0, 72, 106, 77, 61, 26, 67, 46, 29, 96, 37, 61, 52,
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101, 17, 44, 108, 71, 52, 66, 57, 33, 51, 25, 90, 2, 119, 122, 35,
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}, table_2[128] = {
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52, 50, 44, 6, 21, 49, 41, 59, 39, 51, 25, 32, 51, 47, 52, 43,
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37, 4, 40, 34, 61, 12, 28, 4, 58, 23, 8, 15, 12, 22, 9, 18,
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55, 10, 33, 35, 50, 1, 43, 3, 57, 13, 62, 14, 7, 42, 44, 59,
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62, 57, 27, 6, 8, 31, 26, 54, 41, 22, 45, 20, 39, 3, 16, 56,
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48, 2, 21, 28, 36, 42, 60, 33, 34, 18, 0, 11, 24, 10, 17, 61,
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29, 14, 45, 26, 55, 46, 11, 17, 54, 46, 9, 24, 30, 60, 32, 0,
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20, 38, 2, 30, 58, 35, 1, 16, 56, 40, 23, 48, 13, 19, 19, 27,
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31, 53, 47, 38, 63, 15, 49, 5, 37, 53, 25, 36, 63, 29, 5, 7,
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}, table_3[64] = {
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1, 5, 29, 6, 25, 1, 18, 23, 17, 19, 0, 9, 24, 25, 6, 31,
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28, 20, 24, 30, 4, 27, 3, 13, 15, 16, 14, 18, 4, 3, 8, 9,
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20, 0, 12, 26, 21, 8, 28, 2, 29, 2, 15, 7, 11, 22, 14, 10,
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17, 21, 12, 30, 26, 27, 16, 31, 11, 7, 13, 23, 10, 5, 22, 19,
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}, table_4[32] = {
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15, 12, 10, 4, 1, 14, 11, 7, 5, 0, 14, 7, 1, 2, 13, 8,
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10, 3, 4, 9, 6, 0, 3, 2, 5, 6, 8, 9, 11, 13, 15, 12,
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};
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static const u_int8_t *_comp128_table[5] = { table_0, table_1, table_2, table_3, table_4 };
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static inline void
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_comp128_compression_round(u_int8_t *x, int n, const u_int8_t *tbl)
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{
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int i, j, m, a, b, y, z;
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m = 4 - n;
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for (i=0; i<(1<<n); i++)
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for (j=0; j<(1<<m); j++) {
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a = j + i * (2<<m);
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b = a + (1<<m);
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y = (x[a] + (x[b]<<1)) & ((32<<m)-1);
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z = ((x[a]<<1) + x[b]) & ((32<<m)-1);
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x[a] = tbl[y];
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x[b] = tbl[z];
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}
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}
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static inline void
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_comp128_compression(u_int8_t *x)
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{
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int n;
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for (n=0; n<5; n++)
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_comp128_compression_round(x, n, _comp128_table[n]);
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}
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static inline void
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_comp128_bitsfrombytes(u_int8_t *x, u_int8_t *bits)
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{
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int i;
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memset(bits, 0x00, 128);
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for (i=0; i<128; i++)
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if (x[i>>2] & (1<<(3-(i&3))))
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bits[i] = 1;
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}
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static inline void
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_comp128_permutation(u_int8_t *x, u_int8_t *bits)
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{
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int i;
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memset(&x[16], 0x00, 16);
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for (i=0; i<128; i++)
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x[(i>>3)+16] |= bits[(i*17) & 127] << (7-(i&7));
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}
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void
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comp128(u_int8_t *ki, u_int8_t *rand, u_int8_t *sres, u_int8_t *kc)
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{
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int i;
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u_int8_t x[32], bits[128];
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/* x[16-31] = RAND */
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memcpy(&x[16], rand, 16);
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/* Round 1-7 */
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for (i=0; i<7; i++) {
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/* x[0-15] = Ki */
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memcpy(x, ki, 16);
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/* Compression */
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_comp128_compression(x);
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/* FormBitFromBytes */
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_comp128_bitsfrombytes(x, bits);
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/* Permutation */
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_comp128_permutation(x, bits);
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}
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/* Round 8 (final) */
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/* x[0-15] = Ki */
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memcpy(x, ki, 16);
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/* Compression */
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_comp128_compression(x);
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/* Output stage */
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for (i=0; i<8; i+=2)
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sres[i>>1] = x[i]<<4 | x[i+1];
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for (i=0; i<12; i+=2)
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kc[i>>1] = (x[i + 18] << 6) |
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(x[i + 19] << 2) |
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(x[i + 20] >> 2);
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kc[6] = (x[30]<<6) | (x[31]<<2);
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kc[7] = 0;
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}
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