lib/libcrypto/cmac/cmac.c

   1 /* $OpenBSD: cmac.c,v 1.10 2015/09/10 15:56:25 jsing Exp $ */
   2 /* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
   3  * project.
   4  */
   5 /* ====================================================================
   6  * Copyright (c) 2010 The OpenSSL Project.  All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  *
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  *
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in
  17  *    the documentation and/or other materials provided with the
  18  *    distribution.
  19  *
  20  * 3. All advertising materials mentioning features or use of this
  21  *    software must display the following acknowledgment:
  22  *    "This product includes software developed by the OpenSSL Project
  23  *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
  24  *
  25  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
  26  *    endorse or promote products derived from this software without
  27  *    prior written permission. For written permission, please contact
  28  *    licensing@OpenSSL.org.
  29  *
  30  * 5. Products derived from this software may not be called "OpenSSL"
  31  *    nor may "OpenSSL" appear in their names without prior written
  32  *    permission of the OpenSSL Project.
  33  *
  34  * 6. Redistributions of any form whatsoever must retain the following
  35  *    acknowledgment:
  36  *    "This product includes software developed by the OpenSSL Project
  37  *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
  38  *
  39  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
  40  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  41  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  42  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
  43  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  44  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  45  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  46  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  47  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  48  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  49  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  50  * OF THE POSSIBILITY OF SUCH DAMAGE.
  51  * ====================================================================
  52  */
  53
  54 #include <stdio.h>
  55 #include <stdlib.h>
  56 #include <string.h>
  57
  58 #include <openssl/cmac.h>
  59
  60 struct CMAC_CTX_st {
  61         /* Cipher context to use */
  62         EVP_CIPHER_CTX cctx;
  63         /* Keys k1 and k2 */
  64         unsigned char k1[EVP_MAX_BLOCK_LENGTH];
  65         unsigned char k2[EVP_MAX_BLOCK_LENGTH];
  66         /* Temporary block */
  67         unsigned char tbl[EVP_MAX_BLOCK_LENGTH];
  68         /* Last (possibly partial) block */
  69         unsigned char last_block[EVP_MAX_BLOCK_LENGTH];
  70         /* Number of bytes in last block: -1 means context not initialised */
  71         int nlast_block;
  72 };
  73
  74
  75 /* Make temporary keys K1 and K2 */
  76
  77 static void
  78 make_kn(unsigned char *k1, unsigned char *l, int bl)
  79 {
  80         int i;
  81
  82         /* Shift block to left, including carry */
  83         for (i = 0; i < bl; i++) {
  84                 k1[i] = l[i] << 1;
  85                 if (i < bl - 1 && l[i + 1] & 0x80)
  86                         k1[i] |= 1;
  87         }
  88         /* If MSB set fixup with R */
  89         if (l[0] & 0x80)
  90                 k1[bl - 1] ^= bl == 16 ? 0x87 : 0x1b;
  91 }
  92
  93 CMAC_CTX *
  94 CMAC_CTX_new(void)
  95 {
  96         CMAC_CTX *ctx;
  97
  98         ctx = malloc(sizeof(CMAC_CTX));
  99         if (!ctx)
 100                 return NULL;
 101         EVP_CIPHER_CTX_init(&ctx->cctx);
 102         ctx->nlast_block = -1;
 103         return ctx;
 104 }
 105
 106 void
 107 CMAC_CTX_cleanup(CMAC_CTX *ctx)
 108 {
 109         EVP_CIPHER_CTX_cleanup(&ctx->cctx);
 110         explicit_bzero(ctx->tbl, EVP_MAX_BLOCK_LENGTH);
 111         explicit_bzero(ctx->k1, EVP_MAX_BLOCK_LENGTH);
 112         explicit_bzero(ctx->k2, EVP_MAX_BLOCK_LENGTH);
 113         explicit_bzero(ctx->last_block, EVP_MAX_BLOCK_LENGTH);
 114         ctx->nlast_block = -1;
 115 }
 116
 117 EVP_CIPHER_CTX *
 118 CMAC_CTX_get0_cipher_ctx(CMAC_CTX *ctx)
 119 {
 120         return &ctx->cctx;
 121 }
 122
 123 void
 124 CMAC_CTX_free(CMAC_CTX *ctx)
 125 {
 126         if (ctx == NULL)
 127                 return;
 128
 129         CMAC_CTX_cleanup(ctx);
 130         free(ctx);
 131 }
 132
 133 int
 134 CMAC_CTX_copy(CMAC_CTX *out, const CMAC_CTX *in)
 135 {
 136         int bl;
 137
 138         if (in->nlast_block == -1)
 139                 return 0;
 140         if (!EVP_CIPHER_CTX_copy(&out->cctx, &in->cctx))
 141                 return 0;
 142         bl = EVP_CIPHER_CTX_block_size(&in->cctx);
 143         memcpy(out->k1, in->k1, bl);
 144         memcpy(out->k2, in->k2, bl);
 145         memcpy(out->tbl, in->tbl, bl);
 146         memcpy(out->last_block, in->last_block, bl);
 147         out->nlast_block = in->nlast_block;
 148         return 1;
 149 }
 150
 151 int
 152 CMAC_Init(CMAC_CTX *ctx, const void *key, size_t keylen,
 153     const EVP_CIPHER *cipher, ENGINE *impl)
 154 {
 155         static unsigned char zero_iv[EVP_MAX_BLOCK_LENGTH];
 156
 157         /* All zeros means restart */
 158         if (!key && !cipher && !impl && keylen == 0) {
 159                 /* Not initialised */
 160                 if (ctx->nlast_block == -1)
 161                         return 0;
 162                 if (!EVP_EncryptInit_ex(&ctx->cctx, NULL, NULL, NULL, zero_iv))
 163                         return 0;
 164                 memset(ctx->tbl, 0, EVP_CIPHER_CTX_block_size(&ctx->cctx));
 165                 ctx->nlast_block = 0;
 166                 return 1;
 167         }
 168         /* Initialiase context */
 169         if (cipher && !EVP_EncryptInit_ex(&ctx->cctx, cipher, impl, NULL, NULL))
 170                 return 0;
 171         /* Non-NULL key means initialisation complete */
 172         if (key) {
 173                 int bl;
 174
 175                 if (!EVP_CIPHER_CTX_cipher(&ctx->cctx))
 176                         return 0;
 177                 if (!EVP_CIPHER_CTX_set_key_length(&ctx->cctx, keylen))
 178                         return 0;
 179                 if (!EVP_EncryptInit_ex(&ctx->cctx, NULL, NULL, key, zero_iv))
 180                         return 0;
 181                 bl = EVP_CIPHER_CTX_block_size(&ctx->cctx);
 182                 if (!EVP_Cipher(&ctx->cctx, ctx->tbl, zero_iv, bl))
 183                         return 0;
 184                 make_kn(ctx->k1, ctx->tbl, bl);
 185                 make_kn(ctx->k2, ctx->k1, bl);
 186                 explicit_bzero(ctx->tbl, bl);
 187                 /* Reset context again ready for first data block */
 188                 if (!EVP_EncryptInit_ex(&ctx->cctx, NULL, NULL, NULL, zero_iv))
 189                         return 0;
 190                 /* Zero tbl so resume works */
 191                 memset(ctx->tbl, 0, bl);
 192                 ctx->nlast_block = 0;
 193         }
 194         return 1;
 195 }
 196
 197 int
 198 CMAC_Update(CMAC_CTX *ctx, const void *in, size_t dlen)
 199 {
 200         const unsigned char *data = in;
 201         size_t bl;
 202
 203         if (ctx->nlast_block == -1)
 204                 return 0;
 205         if (dlen == 0)
 206                 return 1;
 207         bl = EVP_CIPHER_CTX_block_size(&ctx->cctx);
 208         /* Copy into partial block if we need to */
 209         if (ctx->nlast_block > 0) {
 210                 size_t nleft;
 211
 212                 nleft = bl - ctx->nlast_block;
 213                 if (dlen < nleft)
 214                         nleft = dlen;
 215                 memcpy(ctx->last_block + ctx->nlast_block, data, nleft);
 216                 dlen -= nleft;
 217                 ctx->nlast_block += nleft;
 218                 /* If no more to process return */
 219                 if (dlen == 0)
 220                         return 1;
 221                 data += nleft;
 222                 /* Else not final block so encrypt it */
 223                 if (!EVP_Cipher(&ctx->cctx, ctx->tbl, ctx->last_block, bl))
 224                         return 0;
 225         }
 226         /* Encrypt all but one of the complete blocks left */
 227         while (dlen > bl) {
 228                 if (!EVP_Cipher(&ctx->cctx, ctx->tbl, data, bl))
 229                         return 0;
 230                 dlen -= bl;
 231                 data += bl;
 232         }
 233         /* Copy any data left to last block buffer */
 234         memcpy(ctx->last_block, data, dlen);
 235         ctx->nlast_block = dlen;
 236         return 1;
 237 }
 238
 239 int
 240 CMAC_Final(CMAC_CTX *ctx, unsigned char *out, size_t *poutlen)
 241 {
 242         int i, bl, lb;
 243
 244         if (ctx->nlast_block == -1)
 245                 return 0;
 246         bl = EVP_CIPHER_CTX_block_size(&ctx->cctx);
 247         *poutlen = (size_t)bl;
 248         if (!out)
 249                 return 1;
 250         lb = ctx->nlast_block;
 251         /* Is last block complete? */
 252         if (lb == bl) {
 253                 for (i = 0; i < bl; i++)
 254                         out[i] = ctx->last_block[i] ^ ctx->k1[i];
 255         } else {
 256                 ctx->last_block[lb] = 0x80;
 257                 if (bl - lb > 1)
 258                         memset(ctx->last_block + lb + 1, 0, bl - lb - 1);
 259                 for (i = 0; i < bl; i++)
 260                         out[i] = ctx->last_block[i] ^ ctx->k2[i];
 261         }
 262         if (!EVP_Cipher(&ctx->cctx, out, out, bl)) {
 263                 explicit_bzero(out, bl);
 264                 return 0;
 265         }
 266         return 1;
 267 }
 268
 269 int
 270 CMAC_resume(CMAC_CTX *ctx)
 271 {
 272         if (ctx->nlast_block == -1)
 273                 return 0;
 274         /* The buffer "tbl" containes the last fully encrypted block
 275          * which is the last IV (or all zeroes if no last encrypted block).
 276          * The last block has not been modified since CMAC_final().
 277          * So reinitialising using the last decrypted block will allow
 278          * CMAC to continue after calling CMAC_Final().
 279          */
 280         return EVP_EncryptInit_ex(&ctx->cctx, NULL, NULL, NULL, ctx->tbl);
 281 }