summaryrefslogtreecommitdiffstats
path: root/src/gsm/kasumi.c
blob: f93c002b29d39abce09f57b413511e5ba90118e5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
/*! \file kasumi.c
 * Kasumi cipher and KGcore functions. */
/*
 * (C) 2013 by Max <Max.Suraev@fairwaves.ru>
 * All Rights Reserved
 *
 * SPDX-License-Identifier: GPL-2.0+
 *
 * 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.
 *
 */

#include <stdint.h>
#include <osmocom/core/bits.h>
#include <osmocom/gsm/kasumi.h>

/* See TS 135 202 for constants and full Kasumi spec. */
inline static uint16_t kasumi_FI(uint16_t I, uint16_t skey)
{
	static const uint16_t S7[] = {
		54, 50, 62, 56, 22, 34, 94, 96, 38, 6, 63, 93, 2, 18, 123, 33,
		55, 113, 39, 114, 21, 67, 65, 12, 47, 73, 46, 27, 25, 111, 124, 81,
		53, 9, 121, 79, 52, 60, 58, 48, 101, 127, 40, 120, 104, 70, 71, 43,
		20, 122, 72, 61, 23, 109, 13, 100, 77, 1, 16, 7, 82, 10, 105, 98,
		117, 116, 76, 11, 89, 106, 0,125,118, 99, 86, 69, 30, 57, 126, 87,
		112, 51, 17, 5, 95, 14, 90, 84, 91, 8, 35,103, 32, 97, 28, 66,
		102, 31, 26, 45, 75, 4, 85, 92, 37, 74, 80, 49, 68, 29, 115, 44,
		64, 107, 108, 24, 110, 83, 36, 78, 42, 19, 15, 41, 88, 119, 59, 3
	};
	static const uint16_t S9[] = {
		167, 239, 161, 379, 391, 334,  9, 338, 38, 226, 48, 358, 452, 385, 90, 397,
		183, 253, 147, 331, 415, 340, 51, 362, 306, 500, 262, 82, 216, 159, 356, 177,
		175, 241, 489, 37, 206, 17, 0, 333, 44, 254, 378, 58, 143, 220, 81, 400,
		95, 3, 315, 245, 54, 235, 218, 405, 472, 264, 172, 494, 371, 290, 399, 76,
		165, 197, 395, 121, 257, 480, 423, 212, 240, 28, 462, 176, 406, 507, 288, 223,
		501, 407, 249, 265, 89, 186, 221, 428,164, 74, 440, 196, 458, 421, 350, 163,
		232, 158, 134, 354, 13, 250, 491, 142,191, 69, 193, 425, 152, 227, 366, 135,
		344, 300, 276, 242, 437, 320, 113, 278, 11, 243, 87, 317, 36, 93, 496, 27,
		487, 446, 482, 41, 68, 156, 457, 131, 326, 403, 339, 20, 39, 115, 442, 124,
		475, 384, 508, 53, 112, 170, 479, 151, 126, 169, 73, 268, 279, 321, 168, 364,
		363, 292, 46, 499, 393, 327, 324, 24, 456, 267, 157, 460, 488, 426, 309, 229,
		439, 506, 208, 271, 349, 401, 434, 236, 16, 209, 359, 52, 56, 120, 199, 277,
		465, 416, 252, 287, 246,  6, 83, 305, 420, 345, 153,502, 65, 61, 244, 282,
		173, 222, 418, 67, 386, 368, 261, 101, 476, 291, 195,430, 49, 79, 166, 330,
		280, 383, 373, 128, 382, 408, 155, 495, 367, 388, 274, 107, 459, 417, 62, 454,
		132, 225, 203, 316, 234, 14, 301, 91, 503, 286, 424, 211, 347, 307, 140, 374,
		35, 103, 125, 427, 19, 214, 453, 146, 498, 314, 444, 230, 256, 329, 198, 285,
		50, 116, 78, 410, 10, 205, 510, 171, 231, 45, 139, 467, 29, 86, 505, 32,
		72, 26, 342, 150, 313, 490, 431, 238, 411, 325, 149, 473, 40, 119, 174, 355,
		185, 233, 389, 71, 448, 273, 372, 55, 110, 178, 322, 12, 469, 392, 369, 190,
		1, 109, 375, 137, 181, 88, 75, 308, 260, 484, 98, 272, 370, 275, 412, 111,
		336, 318, 4, 504, 492, 259, 304, 77, 337, 435, 21, 357, 303, 332, 483, 18,
		47, 85, 25, 497, 474, 289, 100, 269, 296, 478, 270, 106, 31, 104, 433, 84,
		414, 486, 394, 96, 99, 154, 511, 148, 413, 361, 409, 255, 162, 215, 302, 201,
		266, 351, 343, 144, 441, 365, 108, 298, 251, 34, 182, 509, 138, 210, 335, 133,
		311, 352, 328, 141, 396, 346, 123, 319, 450, 281, 429, 228, 443, 481, 92, 404,
		485, 422, 248, 297, 23, 213, 130, 466, 22, 217, 283, 70, 294, 360, 419, 127,
		312, 377, 7, 468, 194, 2, 117, 295, 463, 258, 224, 447, 247, 187, 80, 398,
		284, 353, 105, 390, 299, 471, 470, 184, 57, 200, 348, 63, 204, 188, 33, 451,
		97, 30, 310, 219, 94, 160, 129, 493, 64, 179, 263, 102, 189, 207, 114, 402,
		438, 477, 387, 122, 192, 42, 381, 5, 145, 118, 180, 449, 293, 323, 136, 380,
		43, 66, 60, 455, 341, 445, 202, 432, 8, 237, 15, 376, 436, 464, 59, 461
	};
	uint16_t L, R;

	/* Split 16 bit input into two unequal halves: 9 and 7 bits, same for subkey */
	L = I >> 7; /* take 9 bits */
	R = I & 0x7F; /* take 7 bits */

	L = S9[L]  ^ R;
	R = S7[R] ^ (L & 0x7F);

	L ^= (skey & 0x1FF);
	R ^= (skey >> 9);

	L = S9[L]  ^ R;
	R = S7[R] ^ (L & 0x7F);

	return (R << 9) + L;
}

inline static uint32_t kasumi_FO(uint32_t I, const uint16_t *KOi1, const uint16_t *KOi2, const uint16_t *KOi3, const uint16_t *KIi1, const uint16_t *KIi2, const uint16_t *KIi3, unsigned i)
{
	uint16_t L = I >> 16, R = I; /* Split 32 bit input into Left and Right parts */

	L ^= KOi1[i];
	L = kasumi_FI(L, KIi1[i]);
	L ^= R;

	R ^= KOi2[i];
	R = kasumi_FI(R, KIi2[i]);
	R ^= L;

	L ^= KOi3[i];
	L = kasumi_FI(L, KIi3[i]);
	L ^= R;

	return (((uint32_t)R) << 16) + L;
}

inline static uint32_t kasumi_FL(uint32_t I, const uint16_t *KLi1, const uint16_t *KLi2, unsigned i)
{
	uint16_t L = I >> 16, R = I, tmp; /* Split 32 bit input into Left and Right parts */

	tmp = L & KLi1[i];
	R ^= osmo_rol16(tmp, 1);

	tmp = R | KLi2[i];
	L ^= osmo_rol16(tmp, 1);

	return (((uint32_t)L) << 16) + R;
}

uint64_t _kasumi(uint64_t P, const uint16_t *KLi1, const uint16_t *KLi2, const uint16_t *KOi1, const uint16_t *KOi2, const uint16_t *KOi3, const uint16_t *KIi1, const uint16_t *KIi2, const uint16_t *KIi3)
{
	uint32_t i, L = P >> 32, R = P; /* Split 64 bit input into Left and Right parts */

	for (i = 0; i < 8; i++) {
		R ^= kasumi_FO(kasumi_FL(L, KLi1, KLi2, i), KOi1, KOi2, KOi3, KIi1, KIi2, KIi3, i); /* odd round */
		i++;
		L ^= kasumi_FL(kasumi_FO(R, KOi1, KOi2, KOi3, KIi1, KIi2, KIi3, i), KLi1, KLi2, i); /* even round */
	}
	return (((uint64_t)L) << 32) + R; /* Concatenate Left and Right 32 bits into 64 bit ciphertext */
}

void _kasumi_key_expand(const uint8_t *key, uint16_t *KLi1, uint16_t *KLi2, uint16_t *KOi1, uint16_t *KOi2, uint16_t *KOi3, uint16_t *KIi1, uint16_t *KIi2, uint16_t *KIi3)
{
	uint16_t i, C[] = { 0x0123, 0x4567, 0x89AB, 0xCDEF, 0xFEDC, 0xBA98, 0x7654, 0x3210 };

	/* Work with 16 bit subkeys and create prime subkeys */
	for (i = 0; i < 8; i++)
		C[i] ^= osmo_load16be(key + i * 2);
	/* C[] now stores K-prime[] */

	/* Create round-specific subkeys */
	for (i = 0; i < 8; i++) {
		KLi1[i] = osmo_rol16(osmo_load16be(key + i * 2), 1);
		KLi2[i] = C[(i + 2) & 0x7];

		KOi1[i] = osmo_rol16(osmo_load16be(key + ((2 * (i + 1)) & 0xE)), 5);
		KOi2[i] = osmo_rol16(osmo_load16be(key + ((2 * (i + 5)) & 0xE)), 8);
		KOi3[i] = osmo_rol16(osmo_load16be(key + ((2 * (i + 6)) & 0xE)), 13);

		KIi1[i] = C[(i + 4) & 0x7];
		KIi2[i] = C[(i + 3) & 0x7];
		KIi3[i] = C[(i + 7) & 0x7];
	}
}

/* if cl is not multiple of 8 (a byte), co needs to be sized on the upper bound so the entire byte can be written. */
void _kasumi_kgcore(uint8_t CA, uint8_t cb, uint32_t cc, uint8_t cd, const uint8_t *ck, uint8_t *co, uint16_t cl)
{
	uint16_t KLi1[8], KLi2[8], KOi1[8], KOi2[8], KOi3[8], KIi1[8], KIi2[8], KIi3[8], i;
	uint64_t A = ((uint64_t)cc) << 32, BLK = 0, _ca = ((uint64_t)CA << 16) ;
	A |= _ca;
	_ca = (uint64_t)((cb << 3) | (cd << 2)) << 24;
	A |= _ca;
	/* Register loading complete: see TR 55.919 8.2 and TS 55.216 3.2 */

	uint8_t ck_km[16];
	for (i = 0; i < 16; i++)
		ck_km[i] = ck[i] ^ 0x55;
	/* Modified key established */

	/* preliminary round with modified key */
	_kasumi_key_expand(ck_km, KLi1, KLi2, KOi1, KOi2, KOi3, KIi1, KIi2, KIi3);
	A = _kasumi(A, KLi1, KLi2, KOi1, KOi2, KOi3, KIi1, KIi2, KIi3);

	/* Run Kasumi in OFB to obtain enough data for gamma. */
	_kasumi_key_expand(ck, KLi1, KLi2, KOi1, KOi2, KOi3, KIi1, KIi2, KIi3);

	/* i is a block counter */
	for (i = 0; i < cl / 64; i++) {
		BLK = _kasumi(A ^ i ^ BLK, KLi1, KLi2, KOi1, KOi2, KOi3, KIi1, KIi2, KIi3);
		osmo_store64be(BLK, co + (i * 8));
	}

	/* Last 64-byte unaligned round. Take also into account last bits non-byte aligned. */
	uint8_t bytes_remain = cl/8%8 + (cl%8 ? 1 : 0);
	if (bytes_remain) {
		BLK = _kasumi(A ^ (cl / 64) ^ BLK, KLi1, KLi2, KOi1, KOi2, KOi3, KIi1, KIi2, KIi3);
		BLK = BLK >> (8-bytes_remain)*8;
		osmo_store64be_ext(BLK, co + (cl / 64 * 8), bytes_remain);
	}
}