hashes.c 3.6 KB

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  1. /*
  2. * Keyed 32-bit hash function using TEA in a Davis-Meyer function
  3. * H0 = Key
  4. * Hi = E Mi(Hi-1) + Hi-1
  5. *
  6. * (see Applied Cryptography, 2nd edition, p448).
  7. *
  8. * Jeremy Fitzhardinge <jeremy@zip.com.au> 1998
  9. *
  10. * Jeremy has agreed to the contents of reiserfs/README. -Hans
  11. * Yura's function is added (04/07/2000)
  12. */
  13. //
  14. // keyed_hash
  15. // yura_hash
  16. // r5_hash
  17. //
  18. #include <linux/kernel.h>
  19. #include <linux/reiserfs_fs.h>
  20. #include <asm/types.h>
  21. #define DELTA 0x9E3779B9
  22. #define FULLROUNDS 10 /* 32 is overkill, 16 is strong crypto */
  23. #define PARTROUNDS 6 /* 6 gets complete mixing */
  24. /* a, b, c, d - data; h0, h1 - accumulated hash */
  25. #define TEACORE(rounds) \
  26. do { \
  27. u32 sum = 0; \
  28. int n = rounds; \
  29. u32 b0, b1; \
  30. \
  31. b0 = h0; \
  32. b1 = h1; \
  33. \
  34. do \
  35. { \
  36. sum += DELTA; \
  37. b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b); \
  38. b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d); \
  39. } while(--n); \
  40. \
  41. h0 += b0; \
  42. h1 += b1; \
  43. } while(0)
  44. u32 keyed_hash(const signed char *msg, int len)
  45. {
  46. u32 k[] = { 0x9464a485, 0x542e1a94, 0x3e846bff, 0xb75bcfc3 };
  47. u32 h0 = k[0], h1 = k[1];
  48. u32 a, b, c, d;
  49. u32 pad;
  50. int i;
  51. // assert(len >= 0 && len < 256);
  52. pad = (u32) len | ((u32) len << 8);
  53. pad |= pad << 16;
  54. while (len >= 16) {
  55. a = (u32) msg[0] |
  56. (u32) msg[1] << 8 | (u32) msg[2] << 16 | (u32) msg[3] << 24;
  57. b = (u32) msg[4] |
  58. (u32) msg[5] << 8 | (u32) msg[6] << 16 | (u32) msg[7] << 24;
  59. c = (u32) msg[8] |
  60. (u32) msg[9] << 8 |
  61. (u32) msg[10] << 16 | (u32) msg[11] << 24;
  62. d = (u32) msg[12] |
  63. (u32) msg[13] << 8 |
  64. (u32) msg[14] << 16 | (u32) msg[15] << 24;
  65. TEACORE(PARTROUNDS);
  66. len -= 16;
  67. msg += 16;
  68. }
  69. if (len >= 12) {
  70. a = (u32) msg[0] |
  71. (u32) msg[1] << 8 | (u32) msg[2] << 16 | (u32) msg[3] << 24;
  72. b = (u32) msg[4] |
  73. (u32) msg[5] << 8 | (u32) msg[6] << 16 | (u32) msg[7] << 24;
  74. c = (u32) msg[8] |
  75. (u32) msg[9] << 8 |
  76. (u32) msg[10] << 16 | (u32) msg[11] << 24;
  77. d = pad;
  78. for (i = 12; i < len; i++) {
  79. d <<= 8;
  80. d |= msg[i];
  81. }
  82. } else if (len >= 8) {
  83. a = (u32) msg[0] |
  84. (u32) msg[1] << 8 | (u32) msg[2] << 16 | (u32) msg[3] << 24;
  85. b = (u32) msg[4] |
  86. (u32) msg[5] << 8 | (u32) msg[6] << 16 | (u32) msg[7] << 24;
  87. c = d = pad;
  88. for (i = 8; i < len; i++) {
  89. c <<= 8;
  90. c |= msg[i];
  91. }
  92. } else if (len >= 4) {
  93. a = (u32) msg[0] |
  94. (u32) msg[1] << 8 | (u32) msg[2] << 16 | (u32) msg[3] << 24;
  95. b = c = d = pad;
  96. for (i = 4; i < len; i++) {
  97. b <<= 8;
  98. b |= msg[i];
  99. }
  100. } else {
  101. a = b = c = d = pad;
  102. for (i = 0; i < len; i++) {
  103. a <<= 8;
  104. a |= msg[i];
  105. }
  106. }
  107. TEACORE(FULLROUNDS);
  108. /* return 0;*/
  109. return h0 ^ h1;
  110. }
  111. /* What follows in this file is copyright 2000 by Hans Reiser, and the
  112. * licensing of what follows is governed by reiserfs/README */
  113. u32 yura_hash(const signed char *msg, int len)
  114. {
  115. int j, pow;
  116. u32 a, c;
  117. int i;
  118. for (pow = 1, i = 1; i < len; i++)
  119. pow = pow * 10;
  120. if (len == 1)
  121. a = msg[0] - 48;
  122. else
  123. a = (msg[0] - 48) * pow;
  124. for (i = 1; i < len; i++) {
  125. c = msg[i] - 48;
  126. for (pow = 1, j = i; j < len - 1; j++)
  127. pow = pow * 10;
  128. a = a + c * pow;
  129. }
  130. for (; i < 40; i++) {
  131. c = '0' - 48;
  132. for (pow = 1, j = i; j < len - 1; j++)
  133. pow = pow * 10;
  134. a = a + c * pow;
  135. }
  136. for (; i < 256; i++) {
  137. c = i;
  138. for (pow = 1, j = i; j < len - 1; j++)
  139. pow = pow * 10;
  140. a = a + c * pow;
  141. }
  142. a = a << 7;
  143. return a;
  144. }
  145. u32 r5_hash(const signed char *msg, int len)
  146. {
  147. u32 a = 0;
  148. while (*msg) {
  149. a += *msg << 4;
  150. a += *msg >> 4;
  151. a *= 11;
  152. msg++;
  153. }
  154. return a;
  155. }