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+/*
+ * COMP128 implementation
+ *
+ *
+ * This code is inspired by original code from :
+ * Marc Briceno <marc@scard.org>, Ian Goldberg <iang@cs.berkeley.edu>,
+ * and David Wagner <daw@cs.berkeley.edu>
+ *
+ * But it has been fully rewritten from various PDFs found online describing
+ * the algorithm because the licence of the code referenced above was unclear.
+ * A comment snippet from the original code is included below, it describes
+ * where the doc came from and how the algorithm was reverse engineered.
+ *
+ *
+ * (C) 2009 by Sylvain Munaut <tnt@246tNt.com>
+ *
+ * All Rights Reserved
+ *
+ * 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 2 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.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+/*
+ * --- SNIP ---
+ *
+ * This code derived from a leaked document from the GSM standards.
+ * Some missing pieces were filled in by reverse-engineering a working SIM.
+ * We have verified that this is the correct COMP128 algorithm.
+ *
+ * The first page of the document identifies it as
+ * _Technical Information: GSM System Security Study_.
+ * 10-1617-01, 10th June 1988.
+ * The bottom of the title page is marked
+ * Racal Research Ltd.
+ * Worton Drive, Worton Grange Industrial Estate,
+ * Reading, Berks. RG2 0SB, England.
+ * Telephone: Reading (0734) 868601 Telex: 847152
+ * The relevant bits are in Part I, Section 20 (pages 66--67). Enjoy!
+ *
+ * Note: There are three typos in the spec (discovered by
+ * reverse-engineering).
+ * First, "z = (2 * x[n] + x[n]) mod 2^(9-j)" should clearly read
+ * "z = (2 * x[m] + x[n]) mod 2^(9-j)".
+ * Second, the "k" loop in the "Form bits from bytes" section is severely
+ * botched: the k index should run only from 0 to 3, and clearly the range
+ * on "the (8-k)th bit of byte j" is also off (should be 0..7, not 1..8,
+ * to be consistent with the subsequent section).
+ * Third, SRES is taken from the first 8 nibbles of x[], not the last 8 as
+ * claimed in the document. (And the document doesn't specify how Kc is
+ * derived, but that was also easily discovered with reverse engineering.)
+ * All of these typos have been corrected in the following code.
+ *
+ * --- /SNIP ---
+ */
+
+#include <string.h>
+#include <stdint.h>
+
+/* The compression tables (just copied ...) */
+static const uint8_t table_0[512] = {
+ 102, 177, 186, 162, 2, 156, 112, 75, 55, 25, 8, 12, 251, 193, 246, 188,
+ 109, 213, 151, 53, 42, 79, 191, 115, 233, 242, 164, 223, 209, 148, 108, 161,
+ 252, 37, 244, 47, 64, 211, 6, 237, 185, 160, 139, 113, 76, 138, 59, 70,
+ 67, 26, 13, 157, 63, 179, 221, 30, 214, 36, 166, 69, 152, 124, 207, 116,
+ 247, 194, 41, 84, 71, 1, 49, 14, 95, 35, 169, 21, 96, 78, 215, 225,
+ 182, 243, 28, 92, 201, 118, 4, 74, 248, 128, 17, 11, 146, 132, 245, 48,
+ 149, 90, 120, 39, 87, 230, 106, 232, 175, 19, 126, 190, 202, 141, 137, 176,
+ 250, 27, 101, 40, 219, 227, 58, 20, 51, 178, 98, 216, 140, 22, 32, 121,
+ 61, 103, 203, 72, 29, 110, 85, 212, 180, 204, 150, 183, 15, 66, 172, 196,
+ 56, 197, 158, 0, 100, 45, 153, 7, 144, 222, 163, 167, 60, 135, 210, 231,
+ 174, 165, 38, 249, 224, 34, 220, 229, 217, 208, 241, 68, 206, 189, 125, 255,
+ 239, 54, 168, 89, 123, 122, 73, 145, 117, 234, 143, 99, 129, 200, 192, 82,
+ 104, 170, 136, 235, 93, 81, 205, 173, 236, 94, 105, 52, 46, 228, 198, 5,
+ 57, 254, 97, 155, 142, 133, 199, 171, 187, 50, 65, 181, 127, 107, 147, 226,
+ 184, 218, 131, 33, 77, 86, 31, 44, 88, 62, 238, 18, 24, 43, 154, 23,
+ 80, 159, 134, 111, 9, 114, 3, 91, 16, 130, 83, 10, 195, 240, 253, 119,
+ 177, 102, 162, 186, 156, 2, 75, 112, 25, 55, 12, 8, 193, 251, 188, 246,
+ 213, 109, 53, 151, 79, 42, 115, 191, 242, 233, 223, 164, 148, 209, 161, 108,
+ 37, 252, 47, 244, 211, 64, 237, 6, 160, 185, 113, 139, 138, 76, 70, 59,
+ 26, 67, 157, 13, 179, 63, 30, 221, 36, 214, 69, 166, 124, 152, 116, 207,
+ 194, 247, 84, 41, 1, 71, 14, 49, 35, 95, 21, 169, 78, 96, 225, 215,
+ 243, 182, 92, 28, 118, 201, 74, 4, 128, 248, 11, 17, 132, 146, 48, 245,
+ 90, 149, 39, 120, 230, 87, 232, 106, 19, 175, 190, 126, 141, 202, 176, 137,
+ 27, 250, 40, 101, 227, 219, 20, 58, 178, 51, 216, 98, 22, 140, 121, 32,
+ 103, 61, 72, 203, 110, 29, 212, 85, 204, 180, 183, 150, 66, 15, 196, 172,
+ 197, 56, 0, 158, 45, 100, 7, 153, 222, 144, 167, 163, 135, 60, 231, 210,
+ 165, 174, 249, 38, 34, 224, 229, 220, 208, 217, 68, 241, 189, 206, 255, 125,
+ 54, 239, 89, 168, 122, 123, 145, 73, 234, 117, 99, 143, 200, 129, 82, 192,
+ 170, 104, 235, 136, 81, 93, 173, 205, 94, 236, 52, 105, 228, 46, 5, 198,
+ 254, 57, 155, 97, 133, 142, 171, 199, 50, 187, 181, 65, 107, 127, 226, 147,
+ 218, 184, 33, 131, 86, 77, 44, 31, 62, 88, 18, 238, 43, 24, 23, 154,
+ 159, 80, 111, 134, 114, 9, 91, 3, 130, 16, 10, 83, 240, 195, 119, 253,
+}, table_1[256] = {
+ 19, 11, 80, 114, 43, 1, 69, 94, 39, 18, 127, 117, 97, 3, 85, 43,
+ 27, 124, 70, 83, 47, 71, 63, 10, 47, 89, 79, 4, 14, 59, 11, 5,
+ 35, 107, 103, 68, 21, 86, 36, 91, 85, 126, 32, 50, 109, 94, 120, 6,
+ 53, 79, 28, 45, 99, 95, 41, 34, 88, 68, 93, 55, 110, 125, 105, 20,
+ 90, 80, 76, 96, 23, 60, 89, 64, 121, 56, 14, 74, 101, 8, 19, 78,
+ 76, 66, 104, 46, 111, 50, 32, 3, 39, 0, 58, 25, 92, 22, 18, 51,
+ 57, 65, 119, 116, 22, 109, 7, 86, 59, 93, 62, 110, 78, 99, 77, 67,
+ 12, 113, 87, 98, 102, 5, 88, 33, 38, 56, 23, 8, 75, 45, 13, 75,
+ 95, 63, 28, 49, 123, 120, 20, 112, 44, 30, 15, 98, 106, 2, 103, 29,
+ 82, 107, 42, 124, 24, 30, 41, 16, 108, 100, 117, 40, 73, 40, 7, 114,
+ 82, 115, 36, 112, 12, 102, 100, 84, 92, 48, 72, 97, 9, 54, 55, 74,
+ 113, 123, 17, 26, 53, 58, 4, 9, 69, 122, 21, 118, 42, 60, 27, 73,
+ 118, 125, 34, 15, 65, 115, 84, 64, 62, 81, 70, 1, 24, 111, 121, 83,
+ 104, 81, 49, 127, 48, 105, 31, 10, 6, 91, 87, 37, 16, 54, 116, 126,
+ 31, 38, 13, 0, 72, 106, 77, 61, 26, 67, 46, 29, 96, 37, 61, 52,
+ 101, 17, 44, 108, 71, 52, 66, 57, 33, 51, 25, 90, 2, 119, 122, 35,
+}, table_2[128] = {
+ 52, 50, 44, 6, 21, 49, 41, 59, 39, 51, 25, 32, 51, 47, 52, 43,
+ 37, 4, 40, 34, 61, 12, 28, 4, 58, 23, 8, 15, 12, 22, 9, 18,
+ 55, 10, 33, 35, 50, 1, 43, 3, 57, 13, 62, 14, 7, 42, 44, 59,
+ 62, 57, 27, 6, 8, 31, 26, 54, 41, 22, 45, 20, 39, 3, 16, 56,
+ 48, 2, 21, 28, 36, 42, 60, 33, 34, 18, 0, 11, 24, 10, 17, 61,
+ 29, 14, 45, 26, 55, 46, 11, 17, 54, 46, 9, 24, 30, 60, 32, 0,
+ 20, 38, 2, 30, 58, 35, 1, 16, 56, 40, 23, 48, 13, 19, 19, 27,
+ 31, 53, 47, 38, 63, 15, 49, 5, 37, 53, 25, 36, 63, 29, 5, 7,
+}, table_3[64] = {
+ 1, 5, 29, 6, 25, 1, 18, 23, 17, 19, 0, 9, 24, 25, 6, 31,
+ 28, 20, 24, 30, 4, 27, 3, 13, 15, 16, 14, 18, 4, 3, 8, 9,
+ 20, 0, 12, 26, 21, 8, 28, 2, 29, 2, 15, 7, 11, 22, 14, 10,
+ 17, 21, 12, 30, 26, 27, 16, 31, 11, 7, 13, 23, 10, 5, 22, 19,
+}, table_4[32] = {
+ 15, 12, 10, 4, 1, 14, 11, 7, 5, 0, 14, 7, 1, 2, 13, 8,
+ 10, 3, 4, 9, 6, 0, 3, 2, 5, 6, 8, 9, 11, 13, 15, 12,
+};
+
+static const uint8_t *_comp128_table[5] = { table_0, table_1, table_2, table_3, table_4 };
+
+
+static inline void
+_comp128_compression_round(uint8_t *x, int n, const uint8_t *tbl)
+{
+ int i, j, m, a, b, y, z;
+ m = 4 - n;
+ for (i=0; i<(1<<n); i++)
+ for (j=0; j<(1<<m); j++) {
+ a = j + i * (2<<m);
+ b = a + (1<<m);
+ y = (x[a] + (x[b]<<1)) & ((32<<m)-1);
+ z = ((x[a]<<1) + x[b]) & ((32<<m)-1);
+ x[a] = tbl[y];
+ x[b] = tbl[z];
+ }
+}
+
+static inline void
+_comp128_compression(uint8_t *x)
+{
+ int n;
+ for (n=0; n<5; n++)
+ _comp128_compression_round(x, n, _comp128_table[n]);
+}
+
+static inline void
+_comp128_bitsfrombytes(uint8_t *x, uint8_t *bits)
+{
+ int i;
+ memset(bits, 0x00, 128);
+ for (i=0; i<128; i++)
+ if (x[i>>2] & (1<<(3-(i&3))))
+ bits[i] = 1;
+}
+
+static inline void
+_comp128_permutation(uint8_t *x, uint8_t *bits)
+{
+ int i;
+ memset(&x[16], 0x00, 16);
+ for (i=0; i<128; i++)
+ x[(i>>3)+16] |= bits[(i*17) & 127] << (7-(i&7));
+}
+
+void
+comp128(uint8_t *ki, uint8_t *rand, uint8_t *sres, uint8_t *kc)
+{
+ int i;
+ uint8_t x[32], bits[128];
+
+ /* x[16-31] = RAND */
+ memcpy(&x[16], rand, 16);
+
+ /* Round 1-7 */
+ for (i=0; i<7; i++) {
+ /* x[0-15] = Ki */
+ memcpy(x, ki, 16);
+
+ /* Compression */
+ _comp128_compression(x);
+
+ /* FormBitFromBytes */
+ _comp128_bitsfrombytes(x, bits);
+
+ /* Permutation */
+ _comp128_permutation(x, bits);
+ }
+
+ /* Round 8 (final) */
+ /* x[0-15] = Ki */
+ memcpy(x, ki, 16);
+
+ /* Compression */
+ _comp128_compression(x);
+
+ /* Output stage */
+ for (i=0; i<8; i+=2)
+ sres[i>>1] = x[i]<<4 | x[i+1];
+
+ for (i=0; i<12; i+=2)
+ kc[i>>1] = (x[i + 18] << 6) |
+ (x[i + 19] << 2) |
+ (x[i + 20] >> 2);
+
+ kc[6] = (x[30]<<6) | (x[31]<<2);
+ kc[7] = 0;
+}
+