crypto/modes/wrap128.c

   1 /* crypto/modes/wrap128.c */
   2 /*
   3  * Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
   4  * project. Mode with padding contributed by Petr Spacek
   5  * (pspacek@redhat.com).
   6  */
   7 /* ====================================================================
   8  * Copyright (c) 2013 The OpenSSL Project.  All rights reserved.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  *
  14  * 1. Redistributions of source code must retain the above copyright
  15  *    notice, this list of conditions and the following disclaimer.
  16  *
  17  * 2. Redistributions in binary form must reproduce the above copyright
  18  *    notice, this list of conditions and the following disclaimer in
  19  *    the documentation and/or other materials provided with the
  20  *    distribution.
  21  *
  22  * 3. All advertising materials mentioning features or use of this
  23  *    software must display the following acknowledgment:
  24  *    "This product includes software developed by the OpenSSL Project
  25  *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
  26  *
  27  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
  28  *    endorse or promote products derived from this software without
  29  *    prior written permission. For written permission, please contact
  30  *    licensing@OpenSSL.org.
  31  *
  32  * 5. Products derived from this software may not be called "OpenSSL"
  33  *    nor may "OpenSSL" appear in their names without prior written
  34  *    permission of the OpenSSL Project.
  35  *
  36  * 6. Redistributions of any form whatsoever must retain the following
  37  *    acknowledgment:
  38  *    "This product includes software developed by the OpenSSL Project
  39  *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
  40  *
  41  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
  42  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  43  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  44  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
  45  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  46  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  47  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  48  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  49  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  50  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  51  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  52  * OF THE POSSIBILITY OF SUCH DAMAGE.
  53  * ====================================================================
  54  */
  55
  56 /**  Beware!
  57  *
  58  *  Following wrapping modes were designed for AES but this implementation
  59  *  allows you to use them for any 128 bit block cipher.
  60  */
  61
  62 #include "internal/cryptlib.h"
  63 #include <openssl/modes.h>
  64
  65 /** RFC 3394 section 2.2.3.1 Default Initial Value */
  66 static const unsigned char default_iv[] = {
  67     0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6,
  68 };
  69
  70 /** RFC 5649 section 3 Alternative Initial Value 32-bit constant */
  71 static const unsigned char default_aiv[] = {
  72     0xA6, 0x59, 0x59, 0xA6
  73 };
  74
  75 /** Input size limit: lower than maximum of standards but far larger than
  76  *  anything that will be used in practice.
  77  */
  78 #define CRYPTO128_WRAP_MAX (1UL << 31)
  79
  80 /** Wrapping according to RFC 3394 section 2.2.1.
  81  *
  82  *  @param[in]  key    Key value.
  83  *  @param[in]  iv     IV value. Length = 8 bytes. NULL = use default_iv.
  84  *  @param[in]  in     Plaintext as n 64-bit blocks, n >= 2.
  85  *  @param[in]  inlen  Length of in.
  86  *  @param[out] out    Ciphertext. Minimal buffer length = (inlen + 8) bytes.
  87  *                     Input and output buffers can overlap if block function
  88  *                     supports that.
  89  *  @param[in]  block  Block processing function.
  90  *  @return            0 if inlen does not consist of n 64-bit blocks, n >= 2.
  91  *                     or if inlen > CRYPTO128_WRAP_MAX.
  92  *                     Output length if wrapping succeeded.
  93  */
  94 size_t CRYPTO_128_wrap(void *key, const unsigned char *iv,
  95                        unsigned char *out,
  96                        const unsigned char *in, size_t inlen,
  97                        block128_f block)
  98 {
  99     unsigned char *A, B[16], *R;
 100     size_t i, j, t;
 101     if ((inlen & 0x7) || (inlen < 16) || (inlen > CRYPTO128_WRAP_MAX))
 102         return 0;
 103     A = B;
 104     t = 1;
 105     memmove(out + 8, in, inlen);
 106     if (!iv)
 107         iv = default_iv;
 108
 109     memcpy(A, iv, 8);
 110
 111     for (j = 0; j < 6; j++) {
 112         R = out + 8;
 113         for (i = 0; i < inlen; i += 8, t++, R += 8) {
 114             memcpy(B + 8, R, 8);
 115             block(B, B, key);
 116             A[7] ^= (unsigned char)(t & 0xff);
 117             if (t > 0xff) {
 118                 A[6] ^= (unsigned char)((t >> 8) & 0xff);
 119                 A[5] ^= (unsigned char)((t >> 16) & 0xff);
 120                 A[4] ^= (unsigned char)((t >> 24) & 0xff);
 121             }
 122             memcpy(R, B + 8, 8);
 123         }
 124     }
 125     memcpy(out, A, 8);
 126     return inlen + 8;
 127 }
 128
 129 /** Unwrapping according to RFC 3394 section 2.2.2 steps 1-2.
 130  *  The IV check (step 3) is responsibility of the caller.
 131  *
 132  *  @param[in]  key    Key value.
 133  *  @param[out] iv     Unchecked IV value. Minimal buffer length = 8 bytes.
 134  *  @param[out] out    Plaintext without IV.
 135  *                     Minimal buffer length = (inlen - 8) bytes.
 136  *                     Input and output buffers can overlap if block function
 137  *                     supports that.
 138  *  @param[in]  in     Ciphertext as n 64-bit blocks.
 139  *  @param[in]  inlen  Length of in.
 140  *  @param[in]  block  Block processing function.
 141  *  @return            0 if inlen is out of range [24, CRYPTO128_WRAP_MAX]
 142  *                     or if inlen is not a multiple of 8.
 143  *                     Output length otherwise.
 144  */
 145 static size_t crypto_128_unwrap_raw(void *key, unsigned char *iv,
 146                                     unsigned char *out,
 147                                     const unsigned char *in, size_t inlen,
 148                                     block128_f block)
 149 {
 150     unsigned char *A, B[16], *R;
 151     size_t i, j, t;
 152     inlen -= 8;
 153     if ((inlen & 0x7) || (inlen < 16) || (inlen > CRYPTO128_WRAP_MAX))
 154         return 0;
 155     A = B;
 156     t = 6 * (inlen >> 3);
 157     memcpy(A, in, 8);
 158     memmove(out, in + 8, inlen);
 159     for (j = 0; j < 6; j++) {
 160         R = out + inlen - 8;
 161         for (i = 0; i < inlen; i += 8, t--, R -= 8) {
 162             A[7] ^= (unsigned char)(t & 0xff);
 163             if (t > 0xff) {
 164                 A[6] ^= (unsigned char)((t >> 8) & 0xff);
 165                 A[5] ^= (unsigned char)((t >> 16) & 0xff);
 166                 A[4] ^= (unsigned char)((t >> 24) & 0xff);
 167             }
 168             memcpy(B + 8, R, 8);
 169             block(B, B, key);
 170             memcpy(R, B + 8, 8);
 171         }
 172     }
 173     memcpy(iv, A, 8);
 174     return inlen;
 175 }
 176
 177 /** Unwrapping according to RFC 3394 section 2.2.2, including the IV check.
 178  *  The first block of plaintext has to match the supplied IV, otherwise an
 179  *  error is returned.
 180  *
 181  *  @param[in]  key    Key value.
 182  *  @param[out] iv     IV value to match against. Length = 8 bytes.
 183  *                     NULL = use default_iv.
 184  *  @param[out] out    Plaintext without IV.
 185  *                     Minimal buffer length = (inlen - 8) bytes.
 186  *                     Input and output buffers can overlap if block function
 187  *                     supports that.
 188  *  @param[in]  in     Ciphertext as n 64-bit blocks.
 189  *  @param[in]  inlen  Length of in.
 190  *  @param[in]  block  Block processing function.
 191  *  @return            0 if inlen is out of range [24, CRYPTO128_WRAP_MAX]
 192  *                     or if inlen is not a multiple of 8
 193  *                     or if IV doesn't match expected value.
 194  *                     Output length otherwise.
 195  */
 196 size_t CRYPTO_128_unwrap(void *key, const unsigned char *iv,
 197                          unsigned char *out, const unsigned char *in,
 198                          size_t inlen, block128_f block)
 199 {
 200     size_t ret;
 201     unsigned char got_iv[8];
 202
 203     ret = crypto_128_unwrap_raw(key, got_iv, out, in, inlen, block);
 204     if (ret == 0)
 205         return 0;
 206
 207     if (!iv)
 208         iv = default_iv;
 209     if (CRYPTO_memcmp(got_iv, iv, 8)) {
 210         OPENSSL_cleanse(out, ret);
 211         return 0;
 212     }
 213     return ret;
 214 }
 215
 216 /** Wrapping according to RFC 5649 section 4.1.
 217  *
 218  *  @param[in]  key    Key value.
 219  *  @param[in]  icv    (Non-standard) IV, 4 bytes. NULL = use default_aiv.
 220  *  @param[out] out    Ciphertext. Minimal buffer length = (inlen + 15) bytes.
 221  *                     Input and output buffers can overlap if block function
 222  *                     supports that.
 223  *  @param[in]  in     Plaintext as n 64-bit blocks, n >= 2.
 224  *  @param[in]  inlen  Length of in.
 225  *  @param[in]  block  Block processing function.
 226  *  @return            0 if inlen is out of range [1, CRYPTO128_WRAP_MAX].
 227  *                     Output length if wrapping succeeded.
 228  */
 229 size_t CRYPTO_128_wrap_pad(void *key, const unsigned char *icv,
 230                            unsigned char *out,
 231                            const unsigned char *in, size_t inlen,
 232                            block128_f block)
 233 {
 234     /* n: number of 64-bit blocks in the padded key data
 235      *
 236      * If length of plain text is not a multiple of 8, pad the plain text octet
 237      * string on the right with octets of zeros, where final length is the
 238      * smallest multiple of 8 that is greater than length of plain text.
 239      * If length of plain text is a multiple of 8, then there is no padding. */
 240     const size_t blocks_padded = (inlen + 7) / 8; /* CEILING(m/8) */
 241     const size_t padded_len = blocks_padded * 8;
 242     const size_t padding_len = padded_len - inlen;
 243     /* RFC 5649 section 3: Alternative Initial Value */
 244     unsigned char aiv[8];
 245     int ret;
 246
 247     /* Section 1: use 32-bit fixed field for plaintext octet length */
 248     if (inlen == 0 || inlen >= CRYPTO128_WRAP_MAX)
 249         return 0;
 250
 251     /* Section 3: Alternative Initial Value */
 252     if (!icv)
 253         memcpy(aiv, default_aiv, 4);
 254     else
 255         memcpy(aiv, icv, 4);    /* Standard doesn't mention this. */
 256
 257     aiv[4] = (inlen >> 24) & 0xFF;
 258     aiv[5] = (inlen >> 16) & 0xFF;
 259     aiv[6] = (inlen >> 8) & 0xFF;
 260     aiv[7] = inlen & 0xFF;
 261
 262     if (padded_len == 8) {
 263         /*
 264          * Section 4.1 - special case in step 2: If the padded plaintext
 265          * contains exactly eight octets, then prepend the AIV and encrypt
 266          * the resulting 128-bit block using AES in ECB mode.
 267          */
 268         memmove(out + 8, in, inlen);
 269         memcpy(out, aiv, 8);
 270         memset(out + 8 + inlen, 0, padding_len);
 271         block(out, out, key);
 272         ret = 16;               /* AIV + padded input */
 273     } else {
 274         memmove(out, in, inlen);
 275         memset(out + inlen, 0, padding_len); /* Section 4.1 step 1 */
 276         ret = CRYPTO_128_wrap(key, aiv, out, out, padded_len, block);
 277     }
 278
 279     return ret;
 280 }
 281
 282 /** Unwrapping according to RFC 5649 section 4.2.
 283  *
 284  *  @param[in]  key    Key value.
 285  *  @param[in]  icv    (Non-standard) IV, 4 bytes. NULL = use default_aiv.
 286  *  @param[out] out    Plaintext. Minimal buffer length = inlen bytes.
 287  *                     Input and output buffers can overlap if block function
 288  *                     supports that.
 289  *  @param[in]  in     Ciphertext as n 64-bit blocks.
 290  *  @param[in]  inlen  Length of in.
 291  *  @param[in]  block  Block processing function.
 292  *  @return            0 if inlen is out of range [16, CRYPTO128_WRAP_MAX],
 293  *                     or if inlen is not a multiple of 8
 294  *                     or if IV and message length indicator doesn't match.
 295  *                     Output length if unwrapping succeeded and IV matches.
 296  */
 297 size_t CRYPTO_128_unwrap_pad(void *key, const unsigned char *icv,
 298                              unsigned char *out,
 299                              const unsigned char *in, size_t inlen,
 300                              block128_f block)
 301 {
 302     /* n: number of 64-bit blocks in the padded key data */
 303     size_t n = inlen / 8 - 1;
 304     size_t padded_len;
 305     size_t padding_len;
 306     size_t ptext_len;
 307     /* RFC 5649 section 3: Alternative Initial Value */
 308     unsigned char aiv[8];
 309     static unsigned char zeros[8] = { 0x0 };
 310     size_t ret;
 311
 312     /* Section 4.2: Ciphertext length has to be (n+1) 64-bit blocks. */
 313     if ((inlen & 0x7) != 0 || inlen < 16 || inlen >= CRYPTO128_WRAP_MAX)
 314         return 0;
 315
 316     memmove(out, in, inlen);
 317     if (inlen == 16) {
 318         /*
 319          * Section 4.2 - special case in step 1: When n=1, the ciphertext
 320          * contains exactly two 64-bit blocks and they are decrypted as a
 321          * single AES block using AES in ECB mode: AIV | P[1] = DEC(K, C[0] |
 322          * C[1])
 323          */
 324         block(out, out, key);
 325         memcpy(aiv, out, 8);
 326         /* Remove AIV */
 327         memmove(out, out + 8, 8);
 328         padded_len = 8;
 329     } else {
 330         padded_len = inlen - 8;
 331         ret = crypto_128_unwrap_raw(key, aiv, out, out, inlen, block);
 332         if (padded_len != ret) {
 333             OPENSSL_cleanse(out, inlen);
 334             return 0;
 335         }
 336     }
 337
 338     /*
 339      * Section 3: AIV checks: Check that MSB(32,A) = A65959A6. Optionally a
 340      * user-supplied value can be used (even if standard doesn't mention
 341      * this).
 342      */
 343     if ((!icv && CRYPTO_memcmp(aiv, default_aiv, 4))
 344         || (icv && CRYPTO_memcmp(aiv, icv, 4))) {
 345         OPENSSL_cleanse(out, inlen);
 346         return 0;
 347     }
 348
 349     /*
 350      * Check that 8*(n-1) < LSB(32,AIV) <= 8*n. If so, let ptext_len =
 351      * LSB(32,AIV).
 352      */
 353
 354     ptext_len =   ((unsigned int)aiv[4] << 24)
 355                 | ((unsigned int)aiv[5] << 16)
 356                 | ((unsigned int)aiv[6] <<  8)
 357                 |  (unsigned int)aiv[7];
 358     if (8 * (n - 1) >= ptext_len || ptext_len > 8 * n) {
 359         OPENSSL_cleanse(out, inlen);
 360         return 0;
 361     }
 362
 363     /*
 364      * Check that the rightmost padding_len octets of the output data are
 365      * zero.
 366      */
 367     padding_len = padded_len - ptext_len;
 368     if (CRYPTO_memcmp(out + ptext_len, zeros, padding_len) != 0) {
 369         OPENSSL_cleanse(out, inlen);
 370         return 0;
 371     }
 372
 373     /* Section 4.2 step 3: Remove padding */
 374     return ptext_len;
 375 }