crypto/gf128mul.c

   1 /* gf128mul.c - GF(2^128) multiplication functions
   2  *
   3  * Copyright (c) 2003, Dr Brian Gladman, Worcester, UK.
   4  * Copyright (c) 2006, Rik Snel <rsnel@cube.dyndns.org>
   5  *
   6  * Based on Dr Brian Gladman's (GPL'd) work published at
   7  * http://gladman.plushost.co.uk/oldsite/cryptography_technology/index.php
   8  * See the original copyright notice below.
   9  *
  10  * This program is free software; you can redistribute it and/or modify it
  11  * under the terms of the GNU General Public License as published by the Free
  12  * Software Foundation; either version 2 of the License, or (at your option)
  13  * any later version.
  14  */
  15
  16 /*
  17  ---------------------------------------------------------------------------
  18  Copyright (c) 2003, Dr Brian Gladman, Worcester, UK.   All rights reserved.
  19
  20  LICENSE TERMS
  21
  22  The free distribution and use of this software in both source and binary
  23  form is allowed (with or without changes) provided that:
  24
  25    1. distributions of this source code include the above copyright
  26       notice, this list of conditions and the following disclaimer;
  27
  28    2. distributions in binary form include the above copyright
  29       notice, this list of conditions and the following disclaimer
  30       in the documentation and/or other associated materials;
  31
  32    3. the copyright holder's name is not used to endorse products
  33       built using this software without specific written permission.
  34
  35  ALTERNATIVELY, provided that this notice is retained in full, this product
  36  may be distributed under the terms of the GNU General Public License (GPL),
  37  in which case the provisions of the GPL apply INSTEAD OF those given above.
  38
  39  DISCLAIMER
  40
  41  This software is provided 'as is' with no explicit or implied warranties
  42  in respect of its properties, including, but not limited to, correctness
  43  and/or fitness for purpose.
  44  ---------------------------------------------------------------------------
  45  Issue 31/01/2006
  46
  47  This file provides fast multiplication in GF(128) as required by several
  48  cryptographic authentication modes
  49 */
  50
  51 #include <crypto/gf128mul.h>
  52 #include <linux/kernel.h>
  53 #include <linux/module.h>
  54 #include <linux/slab.h>
  55
  56 #define gf128mul_dat(q) { \
  57         q(0x00), q(0x01), q(0x02), q(0x03), q(0x04), q(0x05), q(0x06), q(0x07),\
  58         q(0x08), q(0x09), q(0x0a), q(0x0b), q(0x0c), q(0x0d), q(0x0e), q(0x0f),\
  59         q(0x10), q(0x11), q(0x12), q(0x13), q(0x14), q(0x15), q(0x16), q(0x17),\
  60         q(0x18), q(0x19), q(0x1a), q(0x1b), q(0x1c), q(0x1d), q(0x1e), q(0x1f),\
  61         q(0x20), q(0x21), q(0x22), q(0x23), q(0x24), q(0x25), q(0x26), q(0x27),\
  62         q(0x28), q(0x29), q(0x2a), q(0x2b), q(0x2c), q(0x2d), q(0x2e), q(0x2f),\
  63         q(0x30), q(0x31), q(0x32), q(0x33), q(0x34), q(0x35), q(0x36), q(0x37),\
  64         q(0x38), q(0x39), q(0x3a), q(0x3b), q(0x3c), q(0x3d), q(0x3e), q(0x3f),\
  65         q(0x40), q(0x41), q(0x42), q(0x43), q(0x44), q(0x45), q(0x46), q(0x47),\
  66         q(0x48), q(0x49), q(0x4a), q(0x4b), q(0x4c), q(0x4d), q(0x4e), q(0x4f),\
  67         q(0x50), q(0x51), q(0x52), q(0x53), q(0x54), q(0x55), q(0x56), q(0x57),\
  68         q(0x58), q(0x59), q(0x5a), q(0x5b), q(0x5c), q(0x5d), q(0x5e), q(0x5f),\
  69         q(0x60), q(0x61), q(0x62), q(0x63), q(0x64), q(0x65), q(0x66), q(0x67),\
  70         q(0x68), q(0x69), q(0x6a), q(0x6b), q(0x6c), q(0x6d), q(0x6e), q(0x6f),\
  71         q(0x70), q(0x71), q(0x72), q(0x73), q(0x74), q(0x75), q(0x76), q(0x77),\
  72         q(0x78), q(0x79), q(0x7a), q(0x7b), q(0x7c), q(0x7d), q(0x7e), q(0x7f),\
  73         q(0x80), q(0x81), q(0x82), q(0x83), q(0x84), q(0x85), q(0x86), q(0x87),\
  74         q(0x88), q(0x89), q(0x8a), q(0x8b), q(0x8c), q(0x8d), q(0x8e), q(0x8f),\
  75         q(0x90), q(0x91), q(0x92), q(0x93), q(0x94), q(0x95), q(0x96), q(0x97),\
  76         q(0x98), q(0x99), q(0x9a), q(0x9b), q(0x9c), q(0x9d), q(0x9e), q(0x9f),\
  77         q(0xa0), q(0xa1), q(0xa2), q(0xa3), q(0xa4), q(0xa5), q(0xa6), q(0xa7),\
  78         q(0xa8), q(0xa9), q(0xaa), q(0xab), q(0xac), q(0xad), q(0xae), q(0xaf),\
  79         q(0xb0), q(0xb1), q(0xb2), q(0xb3), q(0xb4), q(0xb5), q(0xb6), q(0xb7),\
  80         q(0xb8), q(0xb9), q(0xba), q(0xbb), q(0xbc), q(0xbd), q(0xbe), q(0xbf),\
  81         q(0xc0), q(0xc1), q(0xc2), q(0xc3), q(0xc4), q(0xc5), q(0xc6), q(0xc7),\
  82         q(0xc8), q(0xc9), q(0xca), q(0xcb), q(0xcc), q(0xcd), q(0xce), q(0xcf),\
  83         q(0xd0), q(0xd1), q(0xd2), q(0xd3), q(0xd4), q(0xd5), q(0xd6), q(0xd7),\
  84         q(0xd8), q(0xd9), q(0xda), q(0xdb), q(0xdc), q(0xdd), q(0xde), q(0xdf),\
  85         q(0xe0), q(0xe1), q(0xe2), q(0xe3), q(0xe4), q(0xe5), q(0xe6), q(0xe7),\
  86         q(0xe8), q(0xe9), q(0xea), q(0xeb), q(0xec), q(0xed), q(0xee), q(0xef),\
  87         q(0xf0), q(0xf1), q(0xf2), q(0xf3), q(0xf4), q(0xf5), q(0xf6), q(0xf7),\
  88         q(0xf8), q(0xf9), q(0xfa), q(0xfb), q(0xfc), q(0xfd), q(0xfe), q(0xff) \
  89 }
  90
  91 /*      Given the value i in 0..255 as the byte overflow when a field element
  92     in GHASH is multiplied by x^8, this function will return the values that
  93     are generated in the lo 16-bit word of the field value by applying the
  94     modular polynomial. The values lo_byte and hi_byte are returned via the
  95     macro xp_fun(lo_byte, hi_byte) so that the values can be assembled into
  96     memory as required by a suitable definition of this macro operating on
  97     the table above
  98 */
  99
 100 #define xx(p, q)        0x##p##q
 101
 102 #define xda_bbe(i) ( \
 103         (i & 0x80 ? xx(43, 80) : 0) ^ (i & 0x40 ? xx(21, c0) : 0) ^ \
 104         (i & 0x20 ? xx(10, e0) : 0) ^ (i & 0x10 ? xx(08, 70) : 0) ^ \
 105         (i & 0x08 ? xx(04, 38) : 0) ^ (i & 0x04 ? xx(02, 1c) : 0) ^ \
 106         (i & 0x02 ? xx(01, 0e) : 0) ^ (i & 0x01 ? xx(00, 87) : 0) \
 107 )
 108
 109 #define xda_lle(i) ( \
 110         (i & 0x80 ? xx(e1, 00) : 0) ^ (i & 0x40 ? xx(70, 80) : 0) ^ \
 111         (i & 0x20 ? xx(38, 40) : 0) ^ (i & 0x10 ? xx(1c, 20) : 0) ^ \
 112         (i & 0x08 ? xx(0e, 10) : 0) ^ (i & 0x04 ? xx(07, 08) : 0) ^ \
 113         (i & 0x02 ? xx(03, 84) : 0) ^ (i & 0x01 ? xx(01, c2) : 0) \
 114 )
 115
 116 static const u16 gf128mul_table_lle[256] = gf128mul_dat(xda_lle);
 117 static const u16 gf128mul_table_bbe[256] = gf128mul_dat(xda_bbe);
 118
 119 /* These functions multiply a field element by x, by x^4 and by x^8
 120  * in the polynomial field representation. It uses 32-bit word operations
 121  * to gain speed but compensates for machine endianess and hence works
 122  * correctly on both styles of machine.
 123  */
 124
 125 static void gf128mul_x_lle(be128 *r, const be128 *x)
 126 {
 127         u64 a = be64_to_cpu(x->a);
 128         u64 b = be64_to_cpu(x->b);
 129         u64 _tt = gf128mul_table_lle[(b << 7) & 0xff];
 130
 131         r->b = cpu_to_be64((b >> 1) | (a << 63));
 132         r->a = cpu_to_be64((a >> 1) ^ (_tt << 48));
 133 }
 134
 135 static void gf128mul_x_bbe(be128 *r, const be128 *x)
 136 {
 137         u64 a = be64_to_cpu(x->a);
 138         u64 b = be64_to_cpu(x->b);
 139         u64 _tt = gf128mul_table_bbe[a >> 63];
 140
 141         r->a = cpu_to_be64((a << 1) | (b >> 63));
 142         r->b = cpu_to_be64((b << 1) ^ _tt);
 143 }
 144
 145 void gf128mul_x_ble(be128 *r, const be128 *x)
 146 {
 147         u64 a = le64_to_cpu(x->a);
 148         u64 b = le64_to_cpu(x->b);
 149         u64 _tt = gf128mul_table_bbe[b >> 63];
 150
 151         r->a = cpu_to_le64((a << 1) ^ _tt);
 152         r->b = cpu_to_le64((b << 1) | (a >> 63));
 153 }
 154 EXPORT_SYMBOL(gf128mul_x_ble);
 155
 156 static void gf128mul_x8_lle(be128 *x)
 157 {
 158         u64 a = be64_to_cpu(x->a);
 159         u64 b = be64_to_cpu(x->b);
 160         u64 _tt = gf128mul_table_lle[b & 0xff];
 161
 162         x->b = cpu_to_be64((b >> 8) | (a << 56));
 163         x->a = cpu_to_be64((a >> 8) ^ (_tt << 48));
 164 }
 165
 166 static void gf128mul_x8_bbe(be128 *x)
 167 {
 168         u64 a = be64_to_cpu(x->a);
 169         u64 b = be64_to_cpu(x->b);
 170         u64 _tt = gf128mul_table_bbe[a >> 56];
 171
 172         x->a = cpu_to_be64((a << 8) | (b >> 56));
 173         x->b = cpu_to_be64((b << 8) ^ _tt);
 174 }
 175
 176 void gf128mul_lle(be128 *r, const be128 *b)
 177 {
 178         be128 p[8];
 179         int i;
 180
 181         p[0] = *r;
 182         for (i = 0; i < 7; ++i)
 183                 gf128mul_x_lle(&p[i + 1], &p[i]);
 184
 185         memset(r, 0, sizeof(*r));
 186         for (i = 0;;) {
 187                 u8 ch = ((u8 *)b)[15 - i];
 188
 189                 if (ch & 0x80)
 190                         be128_xor(r, r, &p[0]);
 191                 if (ch & 0x40)
 192                         be128_xor(r, r, &p[1]);
 193                 if (ch & 0x20)
 194                         be128_xor(r, r, &p[2]);
 195                 if (ch & 0x10)
 196                         be128_xor(r, r, &p[3]);
 197                 if (ch & 0x08)
 198                         be128_xor(r, r, &p[4]);
 199                 if (ch & 0x04)
 200                         be128_xor(r, r, &p[5]);
 201                 if (ch & 0x02)
 202                         be128_xor(r, r, &p[6]);
 203                 if (ch & 0x01)
 204                         be128_xor(r, r, &p[7]);
 205
 206                 if (++i >= 16)
 207                         break;
 208
 209                 gf128mul_x8_lle(r);
 210         }
 211 }
 212 EXPORT_SYMBOL(gf128mul_lle);
 213
 214 void gf128mul_bbe(be128 *r, const be128 *b)
 215 {
 216         be128 p[8];
 217         int i;
 218
 219         p[0] = *r;
 220         for (i = 0; i < 7; ++i)
 221                 gf128mul_x_bbe(&p[i + 1], &p[i]);
 222
 223         memset(r, 0, sizeof(*r));
 224         for (i = 0;;) {
 225                 u8 ch = ((u8 *)b)[i];
 226
 227                 if (ch & 0x80)
 228                         be128_xor(r, r, &p[7]);
 229                 if (ch & 0x40)
 230                         be128_xor(r, r, &p[6]);
 231                 if (ch & 0x20)
 232                         be128_xor(r, r, &p[5]);
 233                 if (ch & 0x10)
 234                         be128_xor(r, r, &p[4]);
 235                 if (ch & 0x08)
 236                         be128_xor(r, r, &p[3]);
 237                 if (ch & 0x04)
 238                         be128_xor(r, r, &p[2]);
 239                 if (ch & 0x02)
 240                         be128_xor(r, r, &p[1]);
 241                 if (ch & 0x01)
 242                         be128_xor(r, r, &p[0]);
 243
 244                 if (++i >= 16)
 245                         break;
 246
 247                 gf128mul_x8_bbe(r);
 248         }
 249 }
 250 EXPORT_SYMBOL(gf128mul_bbe);
 251
 252 /*      This version uses 64k bytes of table space.
 253     A 16 byte buffer has to be multiplied by a 16 byte key
 254     value in GF(128).  If we consider a GF(128) value in
 255     the buffer's lowest byte, we can construct a table of
 256     the 256 16 byte values that result from the 256 values
 257     of this byte.  This requires 4096 bytes. But we also
 258     need tables for each of the 16 higher bytes in the
 259     buffer as well, which makes 64 kbytes in total.
 260 */
 261 /* additional explanation
 262  * t[0][BYTE] contains g*BYTE
 263  * t[1][BYTE] contains g*x^8*BYTE
 264  *  ..
 265  * t[15][BYTE] contains g*x^120*BYTE */
 266 struct gf128mul_64k *gf128mul_init_64k_bbe(const be128 *g)
 267 {
 268         struct gf128mul_64k *t;
 269         int i, j, k;
 270
 271         t = kzalloc(sizeof(*t), GFP_KERNEL);
 272         if (!t)
 273                 goto out;
 274
 275         for (i = 0; i < 16; i++) {
 276                 t->t[i] = kzalloc(sizeof(*t->t[i]), GFP_KERNEL);
 277                 if (!t->t[i]) {
 278                         gf128mul_free_64k(t);
 279                         t = NULL;
 280                         goto out;
 281                 }
 282         }
 283
 284         t->t[0]->t[1] = *g;
 285         for (j = 1; j <= 64; j <<= 1)
 286                 gf128mul_x_bbe(&t->t[0]->t[j + j], &t->t[0]->t[j]);
 287
 288         for (i = 0;;) {
 289                 for (j = 2; j < 256; j += j)
 290                         for (k = 1; k < j; ++k)
 291                                 be128_xor(&t->t[i]->t[j + k],
 292                                           &t->t[i]->t[j], &t->t[i]->t[k]);
 293
 294                 if (++i >= 16)
 295                         break;
 296
 297                 for (j = 128; j > 0; j >>= 1) {
 298                         t->t[i]->t[j] = t->t[i - 1]->t[j];
 299                         gf128mul_x8_bbe(&t->t[i]->t[j]);
 300                 }
 301         }
 302
 303 out:
 304         return t;
 305 }
 306 EXPORT_SYMBOL(gf128mul_init_64k_bbe);
 307
 308 void gf128mul_free_64k(struct gf128mul_64k *t)
 309 {
 310         int i;
 311
 312         for (i = 0; i < 16; i++)
 313                 kzfree(t->t[i]);
 314         kzfree(t);
 315 }
 316 EXPORT_SYMBOL(gf128mul_free_64k);
 317
 318 void gf128mul_64k_bbe(be128 *a, struct gf128mul_64k *t)
 319 {
 320         u8 *ap = (u8 *)a;
 321         be128 r[1];
 322         int i;
 323
 324         *r = t->t[0]->t[ap[15]];
 325         for (i = 1; i < 16; ++i)
 326                 be128_xor(r, r, &t->t[i]->t[ap[15 - i]]);
 327         *a = *r;
 328 }
 329 EXPORT_SYMBOL(gf128mul_64k_bbe);
 330
 331 /*      This version uses 4k bytes of table space.
 332     A 16 byte buffer has to be multiplied by a 16 byte key
 333     value in GF(128).  If we consider a GF(128) value in a
 334     single byte, we can construct a table of the 256 16 byte
 335     values that result from the 256 values of this byte.
 336     This requires 4096 bytes. If we take the highest byte in
 337     the buffer and use this table to get the result, we then
 338     have to multiply by x^120 to get the final value. For the
 339     next highest byte the result has to be multiplied by x^112
 340     and so on. But we can do this by accumulating the result
 341     in an accumulator starting with the result for the top
 342     byte.  We repeatedly multiply the accumulator value by
 343     x^8 and then add in (i.e. xor) the 16 bytes of the next
 344     lower byte in the buffer, stopping when we reach the
 345     lowest byte. This requires a 4096 byte table.
 346 */
 347 struct gf128mul_4k *gf128mul_init_4k_lle(const be128 *g)
 348 {
 349         struct gf128mul_4k *t;
 350         int j, k;
 351
 352         t = kzalloc(sizeof(*t), GFP_KERNEL);
 353         if (!t)
 354                 goto out;
 355
 356         t->t[128] = *g;
 357         for (j = 64; j > 0; j >>= 1)
 358                 gf128mul_x_lle(&t->t[j], &t->t[j+j]);
 359
 360         for (j = 2; j < 256; j += j)
 361                 for (k = 1; k < j; ++k)
 362                         be128_xor(&t->t[j + k], &t->t[j], &t->t[k]);
 363
 364 out:
 365         return t;
 366 }
 367 EXPORT_SYMBOL(gf128mul_init_4k_lle);
 368
 369 struct gf128mul_4k *gf128mul_init_4k_bbe(const be128 *g)
 370 {
 371         struct gf128mul_4k *t;
 372         int j, k;
 373
 374         t = kzalloc(sizeof(*t), GFP_KERNEL);
 375         if (!t)
 376                 goto out;
 377
 378         t->t[1] = *g;
 379         for (j = 1; j <= 64; j <<= 1)
 380                 gf128mul_x_bbe(&t->t[j + j], &t->t[j]);
 381
 382         for (j = 2; j < 256; j += j)
 383                 for (k = 1; k < j; ++k)
 384                         be128_xor(&t->t[j + k], &t->t[j], &t->t[k]);
 385
 386 out:
 387         return t;
 388 }
 389 EXPORT_SYMBOL(gf128mul_init_4k_bbe);
 390
 391 void gf128mul_4k_lle(be128 *a, struct gf128mul_4k *t)
 392 {
 393         u8 *ap = (u8 *)a;
 394         be128 r[1];
 395         int i = 15;
 396
 397         *r = t->t[ap[15]];
 398         while (i--) {
 399                 gf128mul_x8_lle(r);
 400                 be128_xor(r, r, &t->t[ap[i]]);
 401         }
 402         *a = *r;
 403 }
 404 EXPORT_SYMBOL(gf128mul_4k_lle);
 405
 406 void gf128mul_4k_bbe(be128 *a, struct gf128mul_4k *t)
 407 {
 408         u8 *ap = (u8 *)a;
 409         be128 r[1];
 410         int i = 0;
 411
 412         *r = t->t[ap[0]];
 413         while (++i < 16) {
 414                 gf128mul_x8_bbe(r);
 415                 be128_xor(r, r, &t->t[ap[i]]);
 416         }
 417         *a = *r;
 418 }
 419 EXPORT_SYMBOL(gf128mul_4k_bbe);
 420
 421 MODULE_LICENSE("GPL");
 422 MODULE_DESCRIPTION("Functions for multiplying elements of GF(2^128)");