ofb128.c 3.8 KB

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  1. /* ====================================================================
  2. * Copyright (c) 2008 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 <openssl/crypto.h>
  51. #include "modes_lcl.h"
  52. #include <string.h>
  53. #ifndef MODES_DEBUG
  54. # ifndef NDEBUG
  55. # define NDEBUG
  56. # endif
  57. #endif
  58. #include <assert.h>
  59. /* The input and output encrypted as though 128bit ofb mode is being
  60. * used. The extra state information to record how much of the
  61. * 128bit block we have used is contained in *num;
  62. */
  63. void CRYPTO_ofb128_encrypt(const unsigned char *in, unsigned char *out,
  64. size_t len, const void *key,
  65. unsigned char ivec[16], int *num,
  66. block128_f block)
  67. {
  68. unsigned int n;
  69. size_t l=0;
  70. assert(in && out && key && ivec && num);
  71. n = *num;
  72. #if !defined(OPENSSL_SMALL_FOOTPRINT)
  73. if (16%sizeof(size_t) == 0) do { /* always true actually */
  74. while (n && len) {
  75. *(out++) = *(in++) ^ ivec[n];
  76. --len;
  77. n = (n+1) % 16;
  78. }
  79. #if defined(STRICT_ALIGNMENT)
  80. if (((size_t)in|(size_t)out|(size_t)ivec)%sizeof(size_t) != 0)
  81. break;
  82. #endif
  83. while (len>=16) {
  84. (*block)(ivec, ivec, key);
  85. for (; n<16; n+=sizeof(size_t))
  86. *(size_t*)(out+n) =
  87. *(size_t*)(in+n) ^ *(size_t*)(ivec+n);
  88. len -= 16;
  89. out += 16;
  90. in += 16;
  91. n = 0;
  92. }
  93. if (len) {
  94. (*block)(ivec, ivec, key);
  95. while (len--) {
  96. out[n] = in[n] ^ ivec[n];
  97. ++n;
  98. }
  99. }
  100. *num = n;
  101. return;
  102. } while(0);
  103. /* the rest would be commonly eliminated by x86* compiler */
  104. #endif
  105. while (l<len) {
  106. if (n==0) {
  107. (*block)(ivec, ivec, key);
  108. }
  109. out[l] = in[l] ^ ivec[n];
  110. ++l;
  111. n = (n+1) % 16;
  112. }
  113. *num=n;
  114. }