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ofb_enc.c 5.2 KB

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  1. /* crypto/des/ofb_enc.c */
  2. /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  3. * All rights reserved.
  4. *
  5. * This package is an SSL implementation written
  6. * by Eric Young (eay@cryptsoft.com).
  7. * The implementation was written so as to conform with Netscapes SSL.
  8. *
  9. * This library is free for commercial and non-commercial use as long as
  10. * the following conditions are aheared to. The following conditions
  11. * apply to all code found in this distribution, be it the RC4, RSA,
  12. * lhash, DES, etc., code; not just the SSL code. The SSL documentation
  13. * included with this distribution is covered by the same copyright terms
  14. * except that the holder is Tim Hudson (tjh@cryptsoft.com).
  15. *
  16. * Copyright remains Eric Young's, and as such any Copyright notices in
  17. * the code are not to be removed.
  18. * If this package is used in a product, Eric Young should be given attribution
  19. * as the author of the parts of the library used.
  20. * This can be in the form of a textual message at program startup or
  21. * in documentation (online or textual) provided with the package.
  22. *
  23. * Redistribution and use in source and binary forms, with or without
  24. * modification, are permitted provided that the following conditions
  25. * are met:
  26. * 1. Redistributions of source code must retain the copyright
  27. * notice, this list of conditions and the following disclaimer.
  28. * 2. Redistributions in binary form must reproduce the above copyright
  29. * notice, this list of conditions and the following disclaimer in the
  30. * documentation and/or other materials provided with the distribution.
  31. * 3. All advertising materials mentioning features or use of this software
  32. * must display the following acknowledgement:
  33. * "This product includes cryptographic software written by
  34. * Eric Young (eay@cryptsoft.com)"
  35. * The word 'cryptographic' can be left out if the rouines from the library
  36. * being used are not cryptographic related :-).
  37. * 4. If you include any Windows specific code (or a derivative thereof) from
  38. * the apps directory (application code) you must include an acknowledgement:
  39. * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
  40. *
  41. * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
  42. * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  43. * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  44. * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  45. * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  46. * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  47. * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  48. * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  49. * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  50. * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  51. * SUCH DAMAGE.
  52. *
  53. * The licence and distribution terms for any publically available version or
  54. * derivative of this code cannot be changed. i.e. this code cannot simply be
  55. * copied and put under another distribution licence
  56. * [including the GNU Public Licence.]
  57. */
  58. #include "des_locl.h"
  59. /*
  60. * The input and output are loaded in multiples of 8 bits. What this means is
  61. * that if you hame numbits=12 and length=2 the first 12 bits will be
  62. * retrieved from the first byte and half the second. The second 12 bits
  63. * will come from the 3rd and half the 4th byte.
  64. */
  65. void DES_ofb_encrypt(const unsigned char *in, unsigned char *out, int numbits,
  66. long length, DES_key_schedule *schedule,
  67. DES_cblock *ivec)
  68. {
  69. register DES_LONG d0, d1, vv0, vv1, v0, v1, n = (numbits + 7) / 8;
  70. register DES_LONG mask0, mask1;
  71. register long l = length;
  72. register int num = numbits;
  73. DES_LONG ti[2];
  74. unsigned char *iv;
  75. if (num > 64)
  76. return;
  77. if (num > 32) {
  78. mask0 = 0xffffffffL;
  79. if (num >= 64)
  80. mask1 = mask0;
  81. else
  82. mask1 = (1L << (num - 32)) - 1;
  83. } else {
  84. if (num == 32)
  85. mask0 = 0xffffffffL;
  86. else
  87. mask0 = (1L << num) - 1;
  88. mask1 = 0x00000000L;
  89. }
  90. iv = &(*ivec)[0];
  91. c2l(iv, v0);
  92. c2l(iv, v1);
  93. ti[0] = v0;
  94. ti[1] = v1;
  95. while (l-- > 0) {
  96. ti[0] = v0;
  97. ti[1] = v1;
  98. DES_encrypt1((DES_LONG *)ti, schedule, DES_ENCRYPT);
  99. vv0 = ti[0];
  100. vv1 = ti[1];
  101. c2ln(in, d0, d1, n);
  102. in += n;
  103. d0 = (d0 ^ vv0) & mask0;
  104. d1 = (d1 ^ vv1) & mask1;
  105. l2cn(d0, d1, out, n);
  106. out += n;
  107. if (num == 32) {
  108. v0 = v1;
  109. v1 = vv0;
  110. } else if (num == 64) {
  111. v0 = vv0;
  112. v1 = vv1;
  113. } else if (num > 32) { /* && num != 64 */
  114. v0 = ((v1 >> (num - 32)) | (vv0 << (64 - num))) & 0xffffffffL;
  115. v1 = ((vv0 >> (num - 32)) | (vv1 << (64 - num))) & 0xffffffffL;
  116. } else { /* num < 32 */
  117. v0 = ((v0 >> num) | (v1 << (32 - num))) & 0xffffffffL;
  118. v1 = ((v1 >> num) | (vv0 << (32 - num))) & 0xffffffffL;
  119. }
  120. }
  121. iv = &(*ivec)[0];
  122. l2c(v0, iv);
  123. l2c(v1, iv);
  124. v0 = v1 = d0 = d1 = ti[0] = ti[1] = vv0 = vv1 = 0;
  125. }