crypto/cmac/cmac.c

   1 /*
   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 #include "internal/cryptlib.h"
  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 /* Make temporary keys K1 and K2 */
  75
  76 static void make_kn(unsigned char *k1, const unsigned char *l, int bl)
  77 {
  78     int i;
  79     unsigned char c = l[0], carry = c >> 7, cnext;
  80
  81     /* Shift block to left, including carry */
  82     for (i = 0; i < bl - 1; i++, c = cnext)
  83         k1[i] = (c << 1) | ((cnext = l[i + 1]) >> 7);
  84
  85     /* If MSB set fixup with R */
  86     k1[i] = (c << 1) ^ ((0 - carry) & (bl == 16 ? 0x87 : 0x1b));
  87 }
  88
  89 CMAC_CTX *CMAC_CTX_new(void)
  90 {
  91     CMAC_CTX *ctx;
  92
  93     ctx = OPENSSL_malloc(sizeof(*ctx));
  94     if (ctx == NULL)
  95         return NULL;
  96     ctx->cctx = EVP_CIPHER_CTX_new();
  97     if (ctx->cctx == NULL) {
  98         OPENSSL_free(ctx);
  99         return NULL;
 100     }
 101     ctx->nlast_block = -1;
 102     return ctx;
 103 }
 104
 105 void CMAC_CTX_cleanup(CMAC_CTX *ctx)
 106 {
 107     EVP_CIPHER_CTX_free(ctx->cctx);
 108     OPENSSL_cleanse(ctx->tbl, EVP_MAX_BLOCK_LENGTH);
 109     OPENSSL_cleanse(ctx->k1, EVP_MAX_BLOCK_LENGTH);
 110     OPENSSL_cleanse(ctx->k2, EVP_MAX_BLOCK_LENGTH);
 111     OPENSSL_cleanse(ctx->last_block, EVP_MAX_BLOCK_LENGTH);
 112     ctx->nlast_block = -1;
 113 }
 114
 115 EVP_CIPHER_CTX *CMAC_CTX_get0_cipher_ctx(CMAC_CTX *ctx)
 116 {
 117     return ctx->cctx;
 118 }
 119
 120 void CMAC_CTX_free(CMAC_CTX *ctx)
 121 {
 122     if (!ctx)
 123         return;
 124     CMAC_CTX_cleanup(ctx);
 125     OPENSSL_free(ctx);
 126 }
 127
 128 int CMAC_CTX_copy(CMAC_CTX *out, const CMAC_CTX *in)
 129 {
 130     int bl;
 131     if (in->nlast_block == -1)
 132         return 0;
 133     if (!EVP_CIPHER_CTX_copy(out->cctx, in->cctx))
 134         return 0;
 135     bl = EVP_CIPHER_CTX_block_size(in->cctx);
 136     memcpy(out->k1, in->k1, bl);
 137     memcpy(out->k2, in->k2, bl);
 138     memcpy(out->tbl, in->tbl, bl);
 139     memcpy(out->last_block, in->last_block, bl);
 140     out->nlast_block = in->nlast_block;
 141     return 1;
 142 }
 143
 144 int CMAC_Init(CMAC_CTX *ctx, const void *key, size_t keylen,
 145               const EVP_CIPHER *cipher, ENGINE *impl)
 146 {
 147     static const unsigned char zero_iv[EVP_MAX_BLOCK_LENGTH] = { 0 };
 148     /* All zeros means restart */
 149     if (!key && !cipher && !impl && keylen == 0) {
 150         /* Not initialised */
 151         if (ctx->nlast_block == -1)
 152             return 0;
 153         if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, zero_iv))
 154             return 0;
 155         memset(ctx->tbl, 0, EVP_CIPHER_CTX_block_size(ctx->cctx));
 156         ctx->nlast_block = 0;
 157         return 1;
 158     }
 159     /* Initialiase context */
 160     if (cipher && !EVP_EncryptInit_ex(ctx->cctx, cipher, impl, NULL, NULL))
 161         return 0;
 162     /* Non-NULL key means initialisation complete */
 163     if (key) {
 164         int bl;
 165         if (!EVP_CIPHER_CTX_cipher(ctx->cctx))
 166             return 0;
 167         if (!EVP_CIPHER_CTX_set_key_length(ctx->cctx, keylen))
 168             return 0;
 169         if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, key, zero_iv))
 170             return 0;
 171         bl = EVP_CIPHER_CTX_block_size(ctx->cctx);
 172         if (!EVP_Cipher(ctx->cctx, ctx->tbl, zero_iv, bl))
 173             return 0;
 174         make_kn(ctx->k1, ctx->tbl, bl);
 175         make_kn(ctx->k2, ctx->k1, bl);
 176         OPENSSL_cleanse(ctx->tbl, bl);
 177         /* Reset context again ready for first data block */
 178         if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, zero_iv))
 179             return 0;
 180         /* Zero tbl so resume works */
 181         memset(ctx->tbl, 0, bl);
 182         ctx->nlast_block = 0;
 183     }
 184     return 1;
 185 }
 186
 187 int CMAC_Update(CMAC_CTX *ctx, const void *in, size_t dlen)
 188 {
 189     const unsigned char *data = in;
 190     size_t bl;
 191     if (ctx->nlast_block == -1)
 192         return 0;
 193     if (dlen == 0)
 194         return 1;
 195     bl = EVP_CIPHER_CTX_block_size(ctx->cctx);
 196     /* Copy into partial block if we need to */
 197     if (ctx->nlast_block > 0) {
 198         size_t nleft;
 199         nleft = bl - ctx->nlast_block;
 200         if (dlen < nleft)
 201             nleft = dlen;
 202         memcpy(ctx->last_block + ctx->nlast_block, data, nleft);
 203         dlen -= nleft;
 204         ctx->nlast_block += nleft;
 205         /* If no more to process return */
 206         if (dlen == 0)
 207             return 1;
 208         data += nleft;
 209         /* Else not final block so encrypt it */
 210         if (!EVP_Cipher(ctx->cctx, ctx->tbl, ctx->last_block, bl))
 211             return 0;
 212     }
 213     /* Encrypt all but one of the complete blocks left */
 214     while (dlen > bl) {
 215         if (!EVP_Cipher(ctx->cctx, ctx->tbl, data, bl))
 216             return 0;
 217         dlen -= bl;
 218         data += bl;
 219     }
 220     /* Copy any data left to last block buffer */
 221     memcpy(ctx->last_block, data, dlen);
 222     ctx->nlast_block = dlen;
 223     return 1;
 224
 225 }
 226
 227 int CMAC_Final(CMAC_CTX *ctx, unsigned char *out, size_t *poutlen)
 228 {
 229     int i, bl, lb;
 230     if (ctx->nlast_block == -1)
 231         return 0;
 232     bl = EVP_CIPHER_CTX_block_size(ctx->cctx);
 233     *poutlen = (size_t)bl;
 234     if (!out)
 235         return 1;
 236     lb = ctx->nlast_block;
 237     /* Is last block complete? */
 238     if (lb == bl) {
 239         for (i = 0; i < bl; i++)
 240             out[i] = ctx->last_block[i] ^ ctx->k1[i];
 241     } else {
 242         ctx->last_block[lb] = 0x80;
 243         if (bl - lb > 1)
 244             memset(ctx->last_block + lb + 1, 0, bl - lb - 1);
 245         for (i = 0; i < bl; i++)
 246             out[i] = ctx->last_block[i] ^ ctx->k2[i];
 247     }
 248     if (!EVP_Cipher(ctx->cctx, out, out, bl)) {
 249         OPENSSL_cleanse(out, bl);
 250         return 0;
 251     }
 252     return 1;
 253 }
 254
 255 int CMAC_resume(CMAC_CTX *ctx)
 256 {
 257     if (ctx->nlast_block == -1)
 258         return 0;
 259     /*
 260      * The buffer "tbl" containes the last fully encrypted block which is the
 261      * last IV (or all zeroes if no last encrypted block). The last block has
 262      * not been modified since CMAC_final(). So reinitliasing using the last
 263      * decrypted block will allow CMAC to continue after calling
 264      * CMAC_Final().
 265      */
 266     return EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, ctx->tbl);
 267 }