crypto/aegis256.c

   1 /*
   2  * The AEGIS-256 Authenticated-Encryption Algorithm
   3  *
   4  * Copyright (c) 2017-2018 Ondrej Mosnacek <omosnacek@gmail.com>
   5  * Copyright (C) 2017-2018 Red Hat, Inc. All rights reserved.
   6  *
   7  * This program is free software; you can redistribute it and/or modify it
   8  * under the terms of the GNU General Public License as published by the Free
   9  * Software Foundation; either version 2 of the License, or (at your option)
  10  * any later version.
  11  */
  12
  13 #include <crypto/algapi.h>
  14 #include <crypto/internal/aead.h>
  15 #include <crypto/internal/skcipher.h>
  16 #include <crypto/scatterwalk.h>
  17 #include <linux/err.h>
  18 #include <linux/init.h>
  19 #include <linux/kernel.h>
  20 #include <linux/module.h>
  21 #include <linux/scatterlist.h>
  22
  23 #include "aegis.h"
  24
  25 #define AEGIS256_NONCE_SIZE 32
  26 #define AEGIS256_STATE_BLOCKS 6
  27 #define AEGIS256_KEY_SIZE 32
  28 #define AEGIS256_MIN_AUTH_SIZE 8
  29 #define AEGIS256_MAX_AUTH_SIZE 16
  30
  31 struct aegis_state {
  32         union aegis_block blocks[AEGIS256_STATE_BLOCKS];
  33 };
  34
  35 struct aegis_ctx {
  36         union aegis_block key[AEGIS256_KEY_SIZE / AEGIS_BLOCK_SIZE];
  37 };
  38
  39 struct aegis256_ops {
  40         int (*skcipher_walk_init)(struct skcipher_walk *walk,
  41                                   struct aead_request *req, bool atomic);
  42
  43         void (*crypt_chunk)(struct aegis_state *state, u8 *dst,
  44                             const u8 *src, unsigned int size);
  45 };
  46
  47 static void crypto_aegis256_update(struct aegis_state *state)
  48 {
  49         union aegis_block tmp;
  50         unsigned int i;
  51
  52         tmp = state->blocks[AEGIS256_STATE_BLOCKS - 1];
  53         for (i = AEGIS256_STATE_BLOCKS - 1; i > 0; i--)
  54                 crypto_aegis_aesenc(&state->blocks[i], &state->blocks[i - 1],
  55                                     &state->blocks[i]);
  56         crypto_aegis_aesenc(&state->blocks[0], &tmp, &state->blocks[0]);
  57 }
  58
  59 static void crypto_aegis256_update_a(struct aegis_state *state,
  60                                      const union aegis_block *msg)
  61 {
  62         crypto_aegis256_update(state);
  63         crypto_aegis_block_xor(&state->blocks[0], msg);
  64 }
  65
  66 static void crypto_aegis256_update_u(struct aegis_state *state, const void *msg)
  67 {
  68         crypto_aegis256_update(state);
  69         crypto_xor(state->blocks[0].bytes, msg, AEGIS_BLOCK_SIZE);
  70 }
  71
  72 static void crypto_aegis256_init(struct aegis_state *state,
  73                                  const union aegis_block *key,
  74                                  const u8 *iv)
  75 {
  76         union aegis_block key_iv[2];
  77         unsigned int i;
  78
  79         key_iv[0] = key[0];
  80         key_iv[1] = key[1];
  81         crypto_xor(key_iv[0].bytes, iv + 0 * AEGIS_BLOCK_SIZE,
  82                         AEGIS_BLOCK_SIZE);
  83         crypto_xor(key_iv[1].bytes, iv + 1 * AEGIS_BLOCK_SIZE,
  84                         AEGIS_BLOCK_SIZE);
  85
  86         state->blocks[0] = key_iv[0];
  87         state->blocks[1] = key_iv[1];
  88         state->blocks[2] = crypto_aegis_const[1];
  89         state->blocks[3] = crypto_aegis_const[0];
  90         state->blocks[4] = key[0];
  91         state->blocks[5] = key[1];
  92
  93         crypto_aegis_block_xor(&state->blocks[4], &crypto_aegis_const[0]);
  94         crypto_aegis_block_xor(&state->blocks[5], &crypto_aegis_const[1]);
  95
  96         for (i = 0; i < 4; i++) {
  97                 crypto_aegis256_update_a(state, &key[0]);
  98                 crypto_aegis256_update_a(state, &key[1]);
  99                 crypto_aegis256_update_a(state, &key_iv[0]);
 100                 crypto_aegis256_update_a(state, &key_iv[1]);
 101         }
 102 }
 103
 104 static void crypto_aegis256_ad(struct aegis_state *state,
 105                                const u8 *src, unsigned int size)
 106 {
 107         if (AEGIS_ALIGNED(src)) {
 108                 const union aegis_block *src_blk =
 109                                 (const union aegis_block *)src;
 110
 111                 while (size >= AEGIS_BLOCK_SIZE) {
 112                         crypto_aegis256_update_a(state, src_blk);
 113
 114                         size -= AEGIS_BLOCK_SIZE;
 115                         src_blk++;
 116                 }
 117         } else {
 118                 while (size >= AEGIS_BLOCK_SIZE) {
 119                         crypto_aegis256_update_u(state, src);
 120
 121                         size -= AEGIS_BLOCK_SIZE;
 122                         src += AEGIS_BLOCK_SIZE;
 123                 }
 124         }
 125 }
 126
 127 static void crypto_aegis256_encrypt_chunk(struct aegis_state *state, u8 *dst,
 128                                           const u8 *src, unsigned int size)
 129 {
 130         union aegis_block tmp;
 131
 132         if (AEGIS_ALIGNED(src) && AEGIS_ALIGNED(dst)) {
 133                 while (size >= AEGIS_BLOCK_SIZE) {
 134                         union aegis_block *dst_blk =
 135                                         (union aegis_block *)dst;
 136                         const union aegis_block *src_blk =
 137                                         (const union aegis_block *)src;
 138
 139                         tmp = state->blocks[2];
 140                         crypto_aegis_block_and(&tmp, &state->blocks[3]);
 141                         crypto_aegis_block_xor(&tmp, &state->blocks[5]);
 142                         crypto_aegis_block_xor(&tmp, &state->blocks[4]);
 143                         crypto_aegis_block_xor(&tmp, &state->blocks[1]);
 144                         crypto_aegis_block_xor(&tmp, src_blk);
 145
 146                         crypto_aegis256_update_a(state, src_blk);
 147
 148                         *dst_blk = tmp;
 149
 150                         size -= AEGIS_BLOCK_SIZE;
 151                         src += AEGIS_BLOCK_SIZE;
 152                         dst += AEGIS_BLOCK_SIZE;
 153                 }
 154         } else {
 155                 while (size >= AEGIS_BLOCK_SIZE) {
 156                         tmp = state->blocks[2];
 157                         crypto_aegis_block_and(&tmp, &state->blocks[3]);
 158                         crypto_aegis_block_xor(&tmp, &state->blocks[5]);
 159                         crypto_aegis_block_xor(&tmp, &state->blocks[4]);
 160                         crypto_aegis_block_xor(&tmp, &state->blocks[1]);
 161                         crypto_xor(tmp.bytes, src, AEGIS_BLOCK_SIZE);
 162
 163                         crypto_aegis256_update_u(state, src);
 164
 165                         memcpy(dst, tmp.bytes, AEGIS_BLOCK_SIZE);
 166
 167                         size -= AEGIS_BLOCK_SIZE;
 168                         src += AEGIS_BLOCK_SIZE;
 169                         dst += AEGIS_BLOCK_SIZE;
 170                 }
 171         }
 172
 173         if (size > 0) {
 174                 union aegis_block msg = {};
 175                 memcpy(msg.bytes, src, size);
 176
 177                 tmp = state->blocks[2];
 178                 crypto_aegis_block_and(&tmp, &state->blocks[3]);
 179                 crypto_aegis_block_xor(&tmp, &state->blocks[5]);
 180                 crypto_aegis_block_xor(&tmp, &state->blocks[4]);
 181                 crypto_aegis_block_xor(&tmp, &state->blocks[1]);
 182
 183                 crypto_aegis256_update_a(state, &msg);
 184
 185                 crypto_aegis_block_xor(&msg, &tmp);
 186
 187                 memcpy(dst, msg.bytes, size);
 188         }
 189 }
 190
 191 static void crypto_aegis256_decrypt_chunk(struct aegis_state *state, u8 *dst,
 192                                           const u8 *src, unsigned int size)
 193 {
 194         union aegis_block tmp;
 195
 196         if (AEGIS_ALIGNED(src) && AEGIS_ALIGNED(dst)) {
 197                 while (size >= AEGIS_BLOCK_SIZE) {
 198                         union aegis_block *dst_blk =
 199                                         (union aegis_block *)dst;
 200                         const union aegis_block *src_blk =
 201                                         (const union aegis_block *)src;
 202
 203                         tmp = state->blocks[2];
 204                         crypto_aegis_block_and(&tmp, &state->blocks[3]);
 205                         crypto_aegis_block_xor(&tmp, &state->blocks[5]);
 206                         crypto_aegis_block_xor(&tmp, &state->blocks[4]);
 207                         crypto_aegis_block_xor(&tmp, &state->blocks[1]);
 208                         crypto_aegis_block_xor(&tmp, src_blk);
 209
 210                         crypto_aegis256_update_a(state, &tmp);
 211
 212                         *dst_blk = tmp;
 213
 214                         size -= AEGIS_BLOCK_SIZE;
 215                         src += AEGIS_BLOCK_SIZE;
 216                         dst += AEGIS_BLOCK_SIZE;
 217                 }
 218         } else {
 219                 while (size >= AEGIS_BLOCK_SIZE) {
 220                         tmp = state->blocks[2];
 221                         crypto_aegis_block_and(&tmp, &state->blocks[3]);
 222                         crypto_aegis_block_xor(&tmp, &state->blocks[5]);
 223                         crypto_aegis_block_xor(&tmp, &state->blocks[4]);
 224                         crypto_aegis_block_xor(&tmp, &state->blocks[1]);
 225                         crypto_xor(tmp.bytes, src, AEGIS_BLOCK_SIZE);
 226
 227                         crypto_aegis256_update_a(state, &tmp);
 228
 229                         memcpy(dst, tmp.bytes, AEGIS_BLOCK_SIZE);
 230
 231                         size -= AEGIS_BLOCK_SIZE;
 232                         src += AEGIS_BLOCK_SIZE;
 233                         dst += AEGIS_BLOCK_SIZE;
 234                 }
 235         }
 236
 237         if (size > 0) {
 238                 union aegis_block msg = {};
 239                 memcpy(msg.bytes, src, size);
 240
 241                 tmp = state->blocks[2];
 242                 crypto_aegis_block_and(&tmp, &state->blocks[3]);
 243                 crypto_aegis_block_xor(&tmp, &state->blocks[5]);
 244                 crypto_aegis_block_xor(&tmp, &state->blocks[4]);
 245                 crypto_aegis_block_xor(&tmp, &state->blocks[1]);
 246                 crypto_aegis_block_xor(&msg, &tmp);
 247
 248                 memset(msg.bytes + size, 0, AEGIS_BLOCK_SIZE - size);
 249
 250                 crypto_aegis256_update_a(state, &msg);
 251
 252                 memcpy(dst, msg.bytes, size);
 253         }
 254 }
 255
 256 static void crypto_aegis256_process_ad(struct aegis_state *state,
 257                                        struct scatterlist *sg_src,
 258                                        unsigned int assoclen)
 259 {
 260         struct scatter_walk walk;
 261         union aegis_block buf;
 262         unsigned int pos = 0;
 263
 264         scatterwalk_start(&walk, sg_src);
 265         while (assoclen != 0) {
 266                 unsigned int size = scatterwalk_clamp(&walk, assoclen);
 267                 unsigned int left = size;
 268                 void *mapped = scatterwalk_map(&walk);
 269                 const u8 *src = (const u8 *)mapped;
 270
 271                 if (pos + size >= AEGIS_BLOCK_SIZE) {
 272                         if (pos > 0) {
 273                                 unsigned int fill = AEGIS_BLOCK_SIZE - pos;
 274                                 memcpy(buf.bytes + pos, src, fill);
 275                                 crypto_aegis256_update_a(state, &buf);
 276                                 pos = 0;
 277                                 left -= fill;
 278                                 src += fill;
 279                         }
 280
 281                         crypto_aegis256_ad(state, src, left);
 282                         src += left & ~(AEGIS_BLOCK_SIZE - 1);
 283                         left &= AEGIS_BLOCK_SIZE - 1;
 284                 }
 285
 286                 memcpy(buf.bytes + pos, src, left);
 287
 288                 pos += left;
 289                 assoclen -= size;
 290                 scatterwalk_unmap(mapped);
 291                 scatterwalk_advance(&walk, size);
 292                 scatterwalk_done(&walk, 0, assoclen);
 293         }
 294
 295         if (pos > 0) {
 296                 memset(buf.bytes + pos, 0, AEGIS_BLOCK_SIZE - pos);
 297                 crypto_aegis256_update_a(state, &buf);
 298         }
 299 }
 300
 301 static void crypto_aegis256_process_crypt(struct aegis_state *state,
 302                                           struct aead_request *req,
 303                                           const struct aegis256_ops *ops)
 304 {
 305         struct skcipher_walk walk;
 306
 307         ops->skcipher_walk_init(&walk, req, false);
 308
 309         while (walk.nbytes) {
 310                 unsigned int nbytes = walk.nbytes;
 311
 312                 if (nbytes < walk.total)
 313                         nbytes = round_down(nbytes, walk.stride);
 314
 315                 ops->crypt_chunk(state, walk.dst.virt.addr, walk.src.virt.addr,
 316                                  nbytes);
 317
 318                 skcipher_walk_done(&walk, walk.nbytes - nbytes);
 319         }
 320 }
 321
 322 static void crypto_aegis256_final(struct aegis_state *state,
 323                                   union aegis_block *tag_xor,
 324                                   u64 assoclen, u64 cryptlen)
 325 {
 326         u64 assocbits = assoclen * 8;
 327         u64 cryptbits = cryptlen * 8;
 328
 329         union aegis_block tmp;
 330         unsigned int i;
 331
 332         tmp.words64[0] = cpu_to_le64(assocbits);
 333         tmp.words64[1] = cpu_to_le64(cryptbits);
 334
 335         crypto_aegis_block_xor(&tmp, &state->blocks[3]);
 336
 337         for (i = 0; i < 7; i++)
 338                 crypto_aegis256_update_a(state, &tmp);
 339
 340         for (i = 0; i < AEGIS256_STATE_BLOCKS; i++)
 341                 crypto_aegis_block_xor(tag_xor, &state->blocks[i]);
 342 }
 343
 344 static int crypto_aegis256_setkey(struct crypto_aead *aead, const u8 *key,
 345                                   unsigned int keylen)
 346 {
 347         struct aegis_ctx *ctx = crypto_aead_ctx(aead);
 348
 349         if (keylen != AEGIS256_KEY_SIZE) {
 350                 crypto_aead_set_flags(aead, CRYPTO_TFM_RES_BAD_KEY_LEN);
 351                 return -EINVAL;
 352         }
 353
 354         memcpy(ctx->key[0].bytes, key, AEGIS_BLOCK_SIZE);
 355         memcpy(ctx->key[1].bytes, key + AEGIS_BLOCK_SIZE,
 356                         AEGIS_BLOCK_SIZE);
 357         return 0;
 358 }
 359
 360 static int crypto_aegis256_setauthsize(struct crypto_aead *tfm,
 361                                        unsigned int authsize)
 362 {
 363         if (authsize > AEGIS256_MAX_AUTH_SIZE)
 364                 return -EINVAL;
 365         if (authsize < AEGIS256_MIN_AUTH_SIZE)
 366                 return -EINVAL;
 367         return 0;
 368 }
 369
 370 static void crypto_aegis256_crypt(struct aead_request *req,
 371                                   union aegis_block *tag_xor,
 372                                   unsigned int cryptlen,
 373                                   const struct aegis256_ops *ops)
 374 {
 375         struct crypto_aead *tfm = crypto_aead_reqtfm(req);
 376         struct aegis_ctx *ctx = crypto_aead_ctx(tfm);
 377         struct aegis_state state;
 378
 379         crypto_aegis256_init(&state, ctx->key, req->iv);
 380         crypto_aegis256_process_ad(&state, req->src, req->assoclen);
 381         crypto_aegis256_process_crypt(&state, req, ops);
 382         crypto_aegis256_final(&state, tag_xor, req->assoclen, cryptlen);
 383 }
 384
 385 static int crypto_aegis256_encrypt(struct aead_request *req)
 386 {
 387         static const struct aegis256_ops ops = {
 388                 .skcipher_walk_init = skcipher_walk_aead_encrypt,
 389                 .crypt_chunk = crypto_aegis256_encrypt_chunk,
 390         };
 391
 392         struct crypto_aead *tfm = crypto_aead_reqtfm(req);
 393         union aegis_block tag = {};
 394         unsigned int authsize = crypto_aead_authsize(tfm);
 395         unsigned int cryptlen = req->cryptlen;
 396
 397         crypto_aegis256_crypt(req, &tag, cryptlen, &ops);
 398
 399         scatterwalk_map_and_copy(tag.bytes, req->dst, req->assoclen + cryptlen,
 400                                  authsize, 1);
 401         return 0;
 402 }
 403
 404 static int crypto_aegis256_decrypt(struct aead_request *req)
 405 {
 406         static const struct aegis256_ops ops = {
 407                 .skcipher_walk_init = skcipher_walk_aead_decrypt,
 408                 .crypt_chunk = crypto_aegis256_decrypt_chunk,
 409         };
 410         static const u8 zeros[AEGIS256_MAX_AUTH_SIZE] = {};
 411
 412         struct crypto_aead *tfm = crypto_aead_reqtfm(req);
 413         union aegis_block tag;
 414         unsigned int authsize = crypto_aead_authsize(tfm);
 415         unsigned int cryptlen = req->cryptlen - authsize;
 416
 417         scatterwalk_map_and_copy(tag.bytes, req->src, req->assoclen + cryptlen,
 418                                  authsize, 0);
 419
 420         crypto_aegis256_crypt(req, &tag, cryptlen, &ops);
 421
 422         return crypto_memneq(tag.bytes, zeros, authsize) ? -EBADMSG : 0;
 423 }
 424
 425 static int crypto_aegis256_init_tfm(struct crypto_aead *tfm)
 426 {
 427         return 0;
 428 }
 429
 430 static void crypto_aegis256_exit_tfm(struct crypto_aead *tfm)
 431 {
 432 }
 433
 434 static struct aead_alg crypto_aegis256_alg = {
 435         .setkey = crypto_aegis256_setkey,
 436         .setauthsize = crypto_aegis256_setauthsize,
 437         .encrypt = crypto_aegis256_encrypt,
 438         .decrypt = crypto_aegis256_decrypt,
 439         .init = crypto_aegis256_init_tfm,
 440         .exit = crypto_aegis256_exit_tfm,
 441
 442         .ivsize = AEGIS256_NONCE_SIZE,
 443         .maxauthsize = AEGIS256_MAX_AUTH_SIZE,
 444         .chunksize = AEGIS_BLOCK_SIZE,
 445
 446         .base = {
 447                 .cra_blocksize = 1,
 448                 .cra_ctxsize = sizeof(struct aegis_ctx),
 449                 .cra_alignmask = 0,
 450
 451                 .cra_priority = 100,
 452
 453                 .cra_name = "aegis256",
 454                 .cra_driver_name = "aegis256-generic",
 455
 456                 .cra_module = THIS_MODULE,
 457         }
 458 };
 459
 460 static int __init crypto_aegis256_module_init(void)
 461 {
 462         return crypto_register_aead(&crypto_aegis256_alg);
 463 }
 464
 465 static void __exit crypto_aegis256_module_exit(void)
 466 {
 467         crypto_unregister_aead(&crypto_aegis256_alg);
 468 }
 469
 470 module_init(crypto_aegis256_module_init);
 471 module_exit(crypto_aegis256_module_exit);
 472
 473 MODULE_LICENSE("GPL");
 474 MODULE_AUTHOR("Ondrej Mosnacek <omosnacek@gmail.com>");
 475 MODULE_DESCRIPTION("AEGIS-256 AEAD algorithm");
 476 MODULE_ALIAS_CRYPTO("aegis256");
 477 MODULE_ALIAS_CRYPTO("aegis256-generic");