crypto/modes/ocb128.c

   1 /* ====================================================================
   2  * Copyright (c) 2014 The OpenSSL Project.  All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  *
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  *
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in
  13  *    the documentation and/or other materials provided with the
  14  *    distribution.
  15  *
  16  * 3. All advertising materials mentioning features or use of this
  17  *    software must display the following acknowledgment:
  18  *    "This product includes software developed by the OpenSSL Project
  19  *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
  20  *
  21  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
  22  *    endorse or promote products derived from this software without
  23  *    prior written permission. For written permission, please contact
  24  *    openssl-core@openssl.org.
  25  *
  26  * 5. Products derived from this software may not be called "OpenSSL"
  27  *    nor may "OpenSSL" appear in their names without prior written
  28  *    permission of the OpenSSL Project.
  29  *
  30  * 6. Redistributions of any form whatsoever must retain the following
  31  *    acknowledgment:
  32  *    "This product includes software developed by the OpenSSL Project
  33  *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
  34  *
  35  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
  36  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  37  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  38  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
  39  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  40  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  41  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  42  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  43  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  44  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  45  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  46  * OF THE POSSIBILITY OF SUCH DAMAGE.
  47  * ====================================================================
  48  */
  49
  50 #include <string.h>
  51 #include <openssl/crypto.h>
  52 #include "modes_lcl.h"
  53
  54 #ifndef OPENSSL_NO_OCB
  55
  56 /*
  57  * Calculate the number of binary trailing zero's in any given number
  58  */
  59 static u32 ocb_ntz(u64 n)
  60 {
  61     u32 cnt = 0;
  62
  63     /*
  64      * We do a right-to-left simple sequential search. This is surprisingly
  65      * efficient as the distribution of trailing zeros is not uniform,
  66      * e.g. the number of possible inputs with no trailing zeros is equal to
  67      * the number with 1 or more; the number with exactly 1 is equal to the
  68      * number with 2 or more, etc. Checking the last two bits covers 75% of
  69      * all numbers. Checking the last three covers 87.5%
  70      */
  71     while (!(n & 1)) {
  72         n >>= 1;
  73         cnt++;
  74     }
  75     return cnt;
  76 }
  77
  78 /*
  79  * Shift a block of 16 bytes left by shift bits
  80  */
  81 static void ocb_block_lshift(const unsigned char *in, size_t shift,
  82                              unsigned char *out)
  83 {
  84     unsigned char shift_mask;
  85     int i;
  86     unsigned char mask[15];
  87
  88     shift_mask = 0xff;
  89     shift_mask <<= (8 - shift);
  90     for (i = 15; i >= 0; i--) {
  91         if (i > 0) {
  92             mask[i - 1] = in[i] & shift_mask;
  93             mask[i - 1] >>= 8 - shift;
  94         }
  95         out[i] = in[i] << shift;
  96
  97         if (i != 15) {
  98             out[i] ^= mask[i];
  99         }
 100     }
 101 }
 102
 103 /*
 104  * Perform a "double" operation as per OCB spec
 105  */
 106 static void ocb_double(OCB_BLOCK *in, OCB_BLOCK *out)
 107 {
 108     unsigned char mask;
 109
 110     /*
 111      * Calculate the mask based on the most significant bit. There are more
 112      * efficient ways to do this - but this way is constant time
 113      */
 114     mask = in->c[0] & 0x80;
 115     mask >>= 7;
 116     mask *= 135;
 117
 118     ocb_block_lshift(in->c, 1, out->c);
 119
 120     out->c[15] ^= mask;
 121 }
 122
 123 /*
 124  * Perform an xor on in1 and in2 - each of len bytes. Store result in out
 125  */
 126 static void ocb_block_xor(const unsigned char *in1,
 127                           const unsigned char *in2, size_t len,
 128                           unsigned char *out)
 129 {
 130     size_t i;
 131     for (i = 0; i < len; i++) {
 132         out[i] = in1[i] ^ in2[i];
 133     }
 134 }
 135
 136 /*
 137  * Lookup L_index in our lookup table. If we haven't already got it we need to
 138  * calculate it
 139  */
 140 static OCB_BLOCK *ocb_lookup_l(OCB128_CONTEXT *ctx, size_t idx)
 141 {
 142     size_t l_index = ctx->l_index;
 143
 144     if (idx <= l_index) {
 145         return ctx->l + idx;
 146     }
 147
 148     /* We don't have it - so calculate it */
 149     if (idx >= ctx->max_l_index) {
 150         /*
 151          * Each additional entry allows to process almost double as
 152          * much data, so that in linear world the table will need to
 153          * be expanded with smaller and smaller increments. Originally
 154          * it was doubling in size, which was a waste. Growing it
 155          * linearly is not formally optimal, but is simpler to implement.
 156          * We grow table by minimally required 4*n that would accommodate
 157          * the index.
 158          */
 159         ctx->max_l_index += (idx - ctx->max_l_index + 4) & ~3;
 160         ctx->l =
 161             OPENSSL_realloc(ctx->l, ctx->max_l_index * sizeof(OCB_BLOCK));
 162         if (ctx->l == NULL)
 163             return NULL;
 164     }
 165     while (l_index < idx) {
 166         ocb_double(ctx->l + l_index, ctx->l + l_index + 1);
 167         l_index++;
 168     }
 169     ctx->l_index = l_index;
 170
 171     return ctx->l + idx;
 172 }
 173
 174 /*
 175  * Create a new OCB128_CONTEXT
 176  */
 177 OCB128_CONTEXT *CRYPTO_ocb128_new(void *keyenc, void *keydec,
 178                                   block128_f encrypt, block128_f decrypt,
 179                                   ocb128_f stream)
 180 {
 181     OCB128_CONTEXT *octx;
 182     int ret;
 183
 184     if ((octx = OPENSSL_malloc(sizeof(*octx))) != NULL) {
 185         ret = CRYPTO_ocb128_init(octx, keyenc, keydec, encrypt, decrypt,
 186                                  stream);
 187         if (ret)
 188             return octx;
 189         OPENSSL_free(octx);
 190     }
 191
 192     return NULL;
 193 }
 194
 195 /*
 196  * Initialise an existing OCB128_CONTEXT
 197  */
 198 int CRYPTO_ocb128_init(OCB128_CONTEXT *ctx, void *keyenc, void *keydec,
 199                        block128_f encrypt, block128_f decrypt,
 200                        ocb128_f stream)
 201 {
 202     memset(ctx, 0, sizeof(*ctx));
 203     ctx->l_index = 0;
 204     ctx->max_l_index = 5;
 205     ctx->l = OPENSSL_malloc(ctx->max_l_index * 16);
 206     if (ctx->l == NULL)
 207         return 0;
 208
 209     /*
 210      * We set both the encryption and decryption key schedules - decryption
 211      * needs both. Don't really need decryption schedule if only doing
 212      * encryption - but it simplifies things to take it anyway
 213      */
 214     ctx->encrypt = encrypt;
 215     ctx->decrypt = decrypt;
 216     ctx->stream = stream;
 217     ctx->keyenc = keyenc;
 218     ctx->keydec = keydec;
 219
 220     /* L_* = ENCIPHER(K, zeros(128)) */
 221     ctx->encrypt(ctx->l_star.c, ctx->l_star.c, ctx->keyenc);
 222
 223     /* L_$ = double(L_*) */
 224     ocb_double(&ctx->l_star, &ctx->l_dollar);
 225
 226     /* L_0 = double(L_$) */
 227     ocb_double(&ctx->l_dollar, ctx->l);
 228
 229     /* L_{i} = double(L_{i-1}) */
 230     ocb_double(ctx->l, ctx->l+1);
 231     ocb_double(ctx->l+1, ctx->l+2);
 232     ocb_double(ctx->l+2, ctx->l+3);
 233     ocb_double(ctx->l+3, ctx->l+4);
 234     ctx->l_index = 4;   /* enough to process up to 496 bytes */
 235
 236     return 1;
 237 }
 238
 239 /*
 240  * Copy an OCB128_CONTEXT object
 241  */
 242 int CRYPTO_ocb128_copy_ctx(OCB128_CONTEXT *dest, OCB128_CONTEXT *src,
 243                            void *keyenc, void *keydec)
 244 {
 245     memcpy(dest, src, sizeof(OCB128_CONTEXT));
 246     if (keyenc)
 247         dest->keyenc = keyenc;
 248     if (keydec)
 249         dest->keydec = keydec;
 250     if (src->l) {
 251         dest->l = OPENSSL_malloc(src->max_l_index * 16);
 252         if (dest->l == NULL)
 253             return 0;
 254         memcpy(dest->l, src->l, (src->l_index + 1) * 16);
 255     }
 256     return 1;
 257 }
 258
 259 /*
 260  * Set the IV to be used for this operation. Must be 1 - 15 bytes.
 261  */
 262 int CRYPTO_ocb128_setiv(OCB128_CONTEXT *ctx, const unsigned char *iv,
 263                         size_t len, size_t taglen)
 264 {
 265     unsigned char ktop[16], tmp[16], mask;
 266     unsigned char stretch[24], nonce[16];
 267     size_t bottom, shift;
 268
 269     /*
 270      * Spec says IV is 120 bits or fewer - it allows non byte aligned lengths.
 271      * We don't support  this at this stage
 272      */
 273     if ((len > 15) || (len < 1) || (taglen > 16) || (taglen < 1)) {
 274         return -1;
 275     }
 276
 277     /* Nonce = num2str(TAGLEN mod 128,7) || zeros(120-bitlen(N)) || 1 || N */
 278     nonce[0] = ((taglen * 8) % 128) << 1;
 279     memset(nonce + 1, 0, 15);
 280     memcpy(nonce + 16 - len, iv, len);
 281     nonce[15 - len] |= 1;
 282
 283     /* Ktop = ENCIPHER(K, Nonce[1..122] || zeros(6)) */
 284     memcpy(tmp, nonce, 16);
 285     tmp[15] &= 0xc0;
 286     ctx->encrypt(tmp, ktop, ctx->keyenc);
 287
 288     /* Stretch = Ktop || (Ktop[1..64] xor Ktop[9..72]) */
 289     memcpy(stretch, ktop, 16);
 290     ocb_block_xor(ktop, ktop + 1, 8, stretch + 16);
 291
 292     /* bottom = str2num(Nonce[123..128]) */
 293     bottom = nonce[15] & 0x3f;
 294
 295     /* Offset_0 = Stretch[1+bottom..128+bottom] */
 296     shift = bottom % 8;
 297     ocb_block_lshift(stretch + (bottom / 8), shift, ctx->offset.c);
 298     mask = 0xff;
 299     mask <<= 8 - shift;
 300     ctx->offset.c[15] |=
 301         (*(stretch + (bottom / 8) + 16) & mask) >> (8 - shift);
 302
 303     return 1;
 304 }
 305
 306 /*
 307  * Provide any AAD. This can be called multiple times. Only the final time can
 308  * have a partial block
 309  */
 310 int CRYPTO_ocb128_aad(OCB128_CONTEXT *ctx, const unsigned char *aad,
 311                       size_t len)
 312 {
 313     u64 i, all_num_blocks;
 314     size_t num_blocks, last_len;
 315     OCB_BLOCK tmp1;
 316     OCB_BLOCK tmp2;
 317
 318     /* Calculate the number of blocks of AAD provided now, and so far */
 319     num_blocks = len / 16;
 320     all_num_blocks = num_blocks + ctx->blocks_hashed;
 321
 322     /* Loop through all full blocks of AAD */
 323     for (i = ctx->blocks_hashed + 1; i <= all_num_blocks; i++) {
 324         OCB_BLOCK *lookup;
 325         OCB_BLOCK *aad_block;
 326
 327         /* Offset_i = Offset_{i-1} xor L_{ntz(i)} */
 328         lookup = ocb_lookup_l(ctx, ocb_ntz(i));
 329         if (lookup == NULL)
 330             return 0;
 331         ocb_block16_xor(&ctx->offset_aad, lookup, &ctx->offset_aad);
 332
 333         /* Sum_i = Sum_{i-1} xor ENCIPHER(K, A_i xor Offset_i) */
 334         aad_block = (OCB_BLOCK *)(aad + ((i - ctx->blocks_hashed - 1) * 16));
 335         ocb_block16_xor(&ctx->offset_aad, aad_block, &tmp1);
 336         ctx->encrypt(tmp1.c, tmp2.c, ctx->keyenc);
 337         ocb_block16_xor(&ctx->sum, &tmp2, &ctx->sum);
 338     }
 339
 340     /*
 341      * Check if we have any partial blocks left over. This is only valid in the
 342      * last call to this function
 343      */
 344     last_len = len % 16;
 345
 346     if (last_len > 0) {
 347         /* Offset_* = Offset_m xor L_* */
 348         ocb_block16_xor(&ctx->offset_aad, &ctx->l_star, &ctx->offset_aad);
 349
 350         /* CipherInput = (A_* || 1 || zeros(127-bitlen(A_*))) xor Offset_* */
 351         memset(&tmp1, 0, 16);
 352         memcpy(&tmp1, aad + (num_blocks * 16), last_len);
 353         ((unsigned char *)&tmp1)[last_len] = 0x80;
 354         ocb_block16_xor(&ctx->offset_aad, &tmp1, &tmp2);
 355
 356         /* Sum = Sum_m xor ENCIPHER(K, CipherInput) */
 357         ctx->encrypt(tmp2.c, tmp1.c, ctx->keyenc);
 358         ocb_block16_xor(&ctx->sum, &tmp1, &ctx->sum);
 359     }
 360
 361     ctx->blocks_hashed = all_num_blocks;
 362
 363     return 1;
 364 }
 365
 366 /*
 367  * Provide any data to be encrypted. This can be called multiple times. Only
 368  * the final time can have a partial block
 369  */
 370 int CRYPTO_ocb128_encrypt(OCB128_CONTEXT *ctx,
 371                           const unsigned char *in, unsigned char *out,
 372                           size_t len)
 373 {
 374     u64 i, all_num_blocks;
 375     size_t num_blocks, last_len;
 376     OCB_BLOCK tmp1;
 377     OCB_BLOCK tmp2;
 378     OCB_BLOCK pad;
 379
 380     /*
 381      * Calculate the number of blocks of data to be encrypted provided now, and
 382      * so far
 383      */
 384     num_blocks = len / 16;
 385     all_num_blocks = num_blocks + ctx->blocks_processed;
 386
 387     if (num_blocks && all_num_blocks == (size_t)all_num_blocks
 388         && ctx->stream != NULL) {
 389         size_t max_idx = 0, top = (size_t)all_num_blocks;
 390
 391         /*
 392          * See how many L_{i} entries we need to process data at hand
 393          * and pre-compute missing entries in the table [if any]...
 394          */
 395         while (top >>= 1)
 396             max_idx++;
 397         if (ocb_lookup_l(ctx, max_idx) == NULL)
 398             return 0;
 399
 400         ctx->stream(in, out, num_blocks, ctx->keyenc,
 401                     (size_t)ctx->blocks_processed + 1, ctx->offset.c,
 402                     (const unsigned char (*)[16])ctx->l, ctx->checksum.c);
 403     } else {
 404         /* Loop through all full blocks to be encrypted */
 405         for (i = ctx->blocks_processed + 1; i <= all_num_blocks; i++) {
 406             OCB_BLOCK *lookup;
 407             OCB_BLOCK *inblock;
 408             OCB_BLOCK *outblock;
 409
 410             /* Offset_i = Offset_{i-1} xor L_{ntz(i)} */
 411             lookup = ocb_lookup_l(ctx, ocb_ntz(i));
 412             if (lookup == NULL)
 413                 return 0;
 414             ocb_block16_xor(&ctx->offset, lookup, &ctx->offset);
 415
 416             /* C_i = Offset_i xor ENCIPHER(K, P_i xor Offset_i) */
 417             inblock =
 418                 (OCB_BLOCK *)(in + ((i - ctx->blocks_processed - 1) * 16));
 419             ocb_block16_xor_misaligned(&ctx->offset, inblock, &tmp1);
 420             /* Checksum_i = Checksum_{i-1} xor P_i */
 421             ocb_block16_xor_misaligned(&ctx->checksum, inblock, &ctx->checksum);
 422             ctx->encrypt(tmp1.c, tmp2.c, ctx->keyenc);
 423             outblock =
 424                 (OCB_BLOCK *)(out + ((i - ctx->blocks_processed - 1) * 16));
 425             ocb_block16_xor_misaligned(&ctx->offset, &tmp2, outblock);
 426         }
 427     }
 428
 429     /*
 430      * Check if we have any partial blocks left over. This is only valid in the
 431      * last call to this function
 432      */
 433     last_len = len % 16;
 434
 435     if (last_len > 0) {
 436         /* Offset_* = Offset_m xor L_* */
 437         ocb_block16_xor(&ctx->offset, &ctx->l_star, &ctx->offset);
 438
 439         /* Pad = ENCIPHER(K, Offset_*) */
 440         ctx->encrypt(ctx->offset.c, pad.c, ctx->keyenc);
 441
 442         /* C_* = P_* xor Pad[1..bitlen(P_*)] */
 443         ocb_block_xor(in + (len / 16) * 16, (unsigned char *)&pad, last_len,
 444                       out + (num_blocks * 16));
 445
 446         /* Checksum_* = Checksum_m xor (P_* || 1 || zeros(127-bitlen(P_*))) */
 447         memset(&tmp1, 0, 16);
 448         memcpy(&tmp1, in + (len / 16) * 16, last_len);
 449         ((unsigned char *)(&tmp1))[last_len] = 0x80;
 450         ocb_block16_xor(&ctx->checksum, &tmp1, &ctx->checksum);
 451     }
 452
 453     ctx->blocks_processed = all_num_blocks;
 454
 455     return 1;
 456 }
 457
 458 /*
 459  * Provide any data to be decrypted. This can be called multiple times. Only
 460  * the final time can have a partial block
 461  */
 462 int CRYPTO_ocb128_decrypt(OCB128_CONTEXT *ctx,
 463                           const unsigned char *in, unsigned char *out,
 464                           size_t len)
 465 {
 466     u64 i, all_num_blocks;
 467     size_t num_blocks, last_len;
 468     OCB_BLOCK tmp1;
 469     OCB_BLOCK tmp2;
 470     OCB_BLOCK pad;
 471
 472     /*
 473      * Calculate the number of blocks of data to be decrypted provided now, and
 474      * so far
 475      */
 476     num_blocks = len / 16;
 477     all_num_blocks = num_blocks + ctx->blocks_processed;
 478
 479     if (num_blocks && all_num_blocks == (size_t)all_num_blocks
 480         && ctx->stream != NULL) {
 481         size_t max_idx = 0, top = (size_t)all_num_blocks;
 482
 483         /*
 484          * See how many L_{i} entries we need to process data at hand
 485          * and pre-compute missing entries in the table [if any]...
 486          */
 487         while (top >>= 1)
 488             max_idx++;
 489         if (ocb_lookup_l(ctx, max_idx) == NULL)
 490             return 0;
 491
 492         ctx->stream(in, out, num_blocks, ctx->keydec,
 493                     (size_t)ctx->blocks_processed + 1, ctx->offset.c,
 494                     (const unsigned char (*)[16])ctx->l, ctx->checksum.c);
 495     } else {
 496         /* Loop through all full blocks to be decrypted */
 497         for (i = ctx->blocks_processed + 1; i <= all_num_blocks; i++) {
 498             OCB_BLOCK *inblock;
 499             OCB_BLOCK *outblock;
 500
 501             /* Offset_i = Offset_{i-1} xor L_{ntz(i)} */
 502             OCB_BLOCK *lookup = ocb_lookup_l(ctx, ocb_ntz(i));
 503             if (lookup == NULL)
 504                 return 0;
 505             ocb_block16_xor(&ctx->offset, lookup, &ctx->offset);
 506
 507             /* P_i = Offset_i xor DECIPHER(K, C_i xor Offset_i) */
 508             inblock =
 509                 (OCB_BLOCK *)(in + ((i - ctx->blocks_processed - 1) * 16));
 510             ocb_block16_xor_misaligned(&ctx->offset, inblock, &tmp1);
 511             ctx->decrypt(tmp1.c, tmp2.c, ctx->keydec);
 512             outblock =
 513                 (OCB_BLOCK *)(out + ((i - ctx->blocks_processed - 1) * 16));
 514             ocb_block16_xor_misaligned(&ctx->offset, &tmp2, outblock);
 515
 516             /* Checksum_i = Checksum_{i-1} xor P_i */
 517             ocb_block16_xor_misaligned(&ctx->checksum, outblock, &ctx->checksum);
 518         }
 519     }
 520
 521     /*
 522      * Check if we have any partial blocks left over. This is only valid in the
 523      * last call to this function
 524      */
 525     last_len = len % 16;
 526
 527     if (last_len > 0) {
 528         /* Offset_* = Offset_m xor L_* */
 529         ocb_block16_xor(&ctx->offset, &ctx->l_star, &ctx->offset);
 530
 531         /* Pad = ENCIPHER(K, Offset_*) */
 532         ctx->encrypt(ctx->offset.c, pad.c, ctx->keyenc);
 533
 534         /* P_* = C_* xor Pad[1..bitlen(C_*)] */
 535         ocb_block_xor(in + (len / 16) * 16, (unsigned char *)&pad, last_len,
 536                       out + (num_blocks * 16));
 537
 538         /* Checksum_* = Checksum_m xor (P_* || 1 || zeros(127-bitlen(P_*))) */
 539         memset(&tmp1, 0, 16);
 540         memcpy(&tmp1, out + (len / 16) * 16, last_len);
 541         ((unsigned char *)(&tmp1))[last_len] = 0x80;
 542         ocb_block16_xor(&ctx->checksum, &tmp1, &ctx->checksum);
 543     }
 544
 545     ctx->blocks_processed = all_num_blocks;
 546
 547     return 1;
 548 }
 549
 550 /*
 551  * Calculate the tag and verify it against the supplied tag
 552  */
 553 int CRYPTO_ocb128_finish(OCB128_CONTEXT *ctx, const unsigned char *tag,
 554                          size_t len)
 555 {
 556     OCB_BLOCK tmp1, tmp2;
 557
 558     /*
 559      * Tag = ENCIPHER(K, Checksum_* xor Offset_* xor L_$) xor HASH(K,A)
 560      */
 561     ocb_block16_xor(&ctx->checksum, &ctx->offset, &tmp1);
 562     ocb_block16_xor(&tmp1, &ctx->l_dollar, &tmp2);
 563     ctx->encrypt(tmp2.c, tmp1.c, ctx->keyenc);
 564     ocb_block16_xor(&tmp1, &ctx->sum, &ctx->tag);
 565
 566     if (len > 16 || len < 1) {
 567         return -1;
 568     }
 569
 570     /* Compare the tag if we've been given one */
 571     if (tag)
 572         return CRYPTO_memcmp(&ctx->tag, tag, len);
 573     else
 574         return -1;
 575 }
 576
 577 /*
 578  * Retrieve the calculated tag
 579  */
 580 int CRYPTO_ocb128_tag(OCB128_CONTEXT *ctx, unsigned char *tag, size_t len)
 581 {
 582     if (len > 16 || len < 1) {
 583         return -1;
 584     }
 585
 586     /* Calculate the tag */
 587     CRYPTO_ocb128_finish(ctx, NULL, 0);
 588
 589     /* Copy the tag into the supplied buffer */
 590     memcpy(tag, &ctx->tag, len);
 591
 592     return 1;
 593 }
 594
 595 /*
 596  * Release all resources
 597  */
 598 void CRYPTO_ocb128_cleanup(OCB128_CONTEXT *ctx)
 599 {
 600     if (ctx) {
 601         OPENSSL_clear_free(ctx->l, ctx->max_l_index * 16);
 602         OPENSSL_cleanse(ctx, sizeof(*ctx));
 603     }
 604 }
 605
 606 #endif                          /* OPENSSL_NO_OCB */