cfb_enc.c 6.0 KB

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  1. /* crypto/des/cfb_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 "e_os.h"
  59. #include "des_locl.h"
  60. #include <assert.h>
  61. /* The input and output are loaded in multiples of 8 bits.
  62. * What this means is that if you hame numbits=12 and length=2
  63. * the first 12 bits will be retrieved from the first byte and half
  64. * the second. The second 12 bits will come from the 3rd and half the 4th
  65. * byte.
  66. */
  67. /* Until Aug 1 2003 this function did not correctly implement CFB-r, so it
  68. * will not be compatible with any encryption prior to that date. Ben. */
  69. void DES_cfb_encrypt(const unsigned char *in, unsigned char *out, int numbits,
  70. long length, DES_key_schedule *schedule, DES_cblock *ivec,
  71. int enc)
  72. {
  73. register DES_LONG d0,d1,v0,v1;
  74. register unsigned long l=length;
  75. register int num=numbits/8,n=(numbits+7)/8,i,rem=numbits%8;
  76. DES_LONG ti[2];
  77. unsigned char *iv;
  78. #ifndef L_ENDIAN
  79. unsigned char ovec[16];
  80. #else
  81. unsigned int sh[4];
  82. unsigned char *ovec=(unsigned char *)sh;
  83. /* I kind of count that compiler optimizes away this assertioni,*/
  84. assert (sizeof(sh[0])==4); /* as this holds true for all, */
  85. /* but 16-bit platforms... */
  86. #endif
  87. if (numbits<=0 || numbits > 64) return;
  88. iv = &(*ivec)[0];
  89. c2l(iv,v0);
  90. c2l(iv,v1);
  91. if (enc)
  92. {
  93. while (l >= (unsigned long)n)
  94. {
  95. l-=n;
  96. ti[0]=v0;
  97. ti[1]=v1;
  98. DES_encrypt1((DES_LONG *)ti,schedule,DES_ENCRYPT);
  99. c2ln(in,d0,d1,n);
  100. in+=n;
  101. d0^=ti[0];
  102. d1^=ti[1];
  103. l2cn(d0,d1,out,n);
  104. out+=n;
  105. /* 30-08-94 - eay - changed because l>>32 and
  106. * l<<32 are bad under gcc :-( */
  107. if (numbits == 32)
  108. { v0=v1; v1=d0; }
  109. else if (numbits == 64)
  110. { v0=d0; v1=d1; }
  111. else
  112. {
  113. #ifndef L_ENDIAN
  114. iv=&ovec[0];
  115. l2c(v0,iv);
  116. l2c(v1,iv);
  117. l2c(d0,iv);
  118. l2c(d1,iv);
  119. #else
  120. sh[0]=v0, sh[1]=v1, sh[2]=d0, sh[3]=d1;
  121. #endif
  122. if (rem==0)
  123. memmove(ovec,ovec+num,8);
  124. else
  125. for(i=0 ; i < 8 ; ++i)
  126. ovec[i]=ovec[i+num]<<rem |
  127. ovec[i+num+1]>>(8-rem);
  128. #ifdef L_ENDIAN
  129. v0=sh[0], v1=sh[1];
  130. #else
  131. iv=&ovec[0];
  132. c2l(iv,v0);
  133. c2l(iv,v1);
  134. #endif
  135. }
  136. }
  137. }
  138. else
  139. {
  140. while (l >= (unsigned long)n)
  141. {
  142. l-=n;
  143. ti[0]=v0;
  144. ti[1]=v1;
  145. DES_encrypt1((DES_LONG *)ti,schedule,DES_ENCRYPT);
  146. c2ln(in,d0,d1,n);
  147. in+=n;
  148. /* 30-08-94 - eay - changed because l>>32 and
  149. * l<<32 are bad under gcc :-( */
  150. if (numbits == 32)
  151. { v0=v1; v1=d0; }
  152. else if (numbits == 64)
  153. { v0=d0; v1=d1; }
  154. else
  155. {
  156. #ifndef L_ENDIAN
  157. iv=&ovec[0];
  158. l2c(v0,iv);
  159. l2c(v1,iv);
  160. l2c(d0,iv);
  161. l2c(d1,iv);
  162. #else
  163. sh[0]=v0, sh[1]=v1, sh[2]=d0, sh[3]=d1;
  164. #endif
  165. if (rem==0)
  166. memmove(ovec,ovec+num,8);
  167. else
  168. for(i=0 ; i < 8 ; ++i)
  169. ovec[i]=ovec[i+num]<<rem |
  170. ovec[i+num+1]>>(8-rem);
  171. #ifdef L_ENDIAN
  172. v0=sh[0], v1=sh[1];
  173. #else
  174. iv=&ovec[0];
  175. c2l(iv,v0);
  176. c2l(iv,v1);
  177. #endif
  178. }
  179. d0^=ti[0];
  180. d1^=ti[1];
  181. l2cn(d0,d1,out,n);
  182. out+=n;
  183. }
  184. }
  185. iv = &(*ivec)[0];
  186. l2c(v0,iv);
  187. l2c(v1,iv);
  188. v0=v1=d0=d1=ti[0]=ti[1]=0;
  189. }