1. // Example use
  2. System.Text.ASCIIEncoding AsciiEncoding = new System.Text.ASCIIEncoding();
  3. byte[] Checksum = Calculate(AsciiEncoding.GetBytes(“Checksum This!”)); // String to bytes
  4. MessageBox.Show(AsciiEncoding.GetString(Checksum)); // Return checksum
  6. // The CRC value table
  7. private static readonly UInt32[] CRCTable =
  8. {
  9. 0×00000000, 0×77073096, 0xee0e612c, 0×990951ba, 0×076dc419,
  10. 0×706af48f, 0xe963a535, 0×9e6495a3, 0×0edb8832, 0×79dcb8a4,
  11. 0xe0d5e91e, 0×97d2d988, 0×09b64c2b, 0×7eb17cbd, 0xe7b82d07,
  12. 0×90bf1d91, 0×1db71064, 0×6ab020f2, 0xf3b97148, 0×84be41de,
  13. 0×1adad47d, 0×6ddde4eb, 0xf4d4b551, 0×83d385c7, 0×136c9856,
  14. 0×646ba8c0, 0xfd62f97a, 0×8a65c9ec, 0×14015c4f, 0×63066cd9,
  15. 0xfa0f3d63, 0×8d080df5, 0×3b6e20c8, 0×4c69105e, 0xd56041e4,
  16. 0xa2677172, 0×3c03e4d1, 0×4b04d447, 0xd20d85fd, 0xa50ab56b,
  17. 0×35b5a8fa, 0×42b2986c, 0xdbbbc9d6, 0xacbcf940, 0×32d86ce3,
  18. 0×45df5c75, 0xdcd60dcf, 0xabd13d59, 0×26d930ac, 0×51de003a,
  19. 0xc8d75180, 0xbfd06116, 0×21b4f4b5, 0×56b3c423, 0xcfba9599,
  20. 0xb8bda50f, 0×2802b89e, 0×5f058808, 0xc60cd9b2, 0xb10be924,
  21. 0×2f6f7c87, 0×58684c11, 0xc1611dab, 0xb6662d3d, 0×76dc4190,
  22. 0×01db7106, 0×98d220bc, 0xefd5102a, 0×71b18589, 0×06b6b51f,
  23. 0×9fbfe4a5, 0xe8b8d433, 0×7807c9a2, 0×0f00f934, 0×9609a88e,
  24. 0xe10e9818, 0×7f6a0dbb, 0×086d3d2d, 0×91646c97, 0xe6635c01,
  25. 0×6b6b51f4, 0×1c6c6162, 0×856530d8, 0xf262004e, 0×6c0695ed,
  26. 0×1b01a57b, 0×8208f4c1, 0xf50fc457, 0×65b0d9c6, 0×12b7e950,
  27. 0×8bbeb8ea, 0xfcb9887c, 0×62dd1ddf, 0×15da2d49, 0×8cd37cf3,
  28. 0xfbd44c65, 0×4db26158, 0×3ab551ce, 0xa3bc0074, 0xd4bb30e2,
  29. 0×4adfa541, 0×3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, 0×4369e96a,
  30. 0×346ed9fc, 0xad678846, 0xda60b8d0, 0×44042d73, 0×33031de5,
  31. 0xaa0a4c5f, 0xdd0d7cc9, 0×5005713c, 0×270241aa, 0xbe0b1010,
  32. 0xc90c2086, 0×5768b525, 0×206f85b3, 0xb966d409, 0xce61e49f,
  33. 0×5edef90e, 0×29d9c998, 0xb0d09822, 0xc7d7a8b4, 0×59b33d17,
  34. 0×2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0×9abfb3b6,
  35. 0×03b6e20c, 0×74b1d29a, 0xead54739, 0×9dd277af, 0×04db2615,
  36. 0×73dc1683, 0xe3630b12, 0×94643b84, 0×0d6d6a3e, 0×7a6a5aa8,
  37. 0xe40ecf0b, 0×9309ff9d, 0×0a00ae27, 0×7d079eb1, 0xf00f9344,
  38. 0×8708a3d2, 0×1e01f268, 0×6906c2fe, 0xf762575d, 0×806567cb,
  39. 0×196c3671, 0×6e6b06e7, 0xfed41b76, 0×89d32be0, 0×10da7a5a,
  40. 0×67dd4acc, 0xf9b9df6f, 0×8ebeeff9, 0×17b7be43, 0×60b08ed5,
  41. 0xd6d6a3e8, 0xa1d1937e, 0×38d8c2c4, 0×4fdff252, 0xd1bb67f1,
  42. 0xa6bc5767, 0×3fb506dd, 0×48b2364b, 0xd80d2bda, 0xaf0a1b4c,
  43. 0×36034af6, 0×41047a60, 0xdf60efc3, 0xa867df55, 0×316e8eef,
  44. 0×4669be79, 0xcb61b38c, 0xbc66831a, 0×256fd2a0, 0×5268e236,
  45. 0xcc0c7795, 0xbb0b4703, 0×220216b9, 0×5505262f, 0xc5ba3bbe,
  46. 0xb2bd0b28, 0×2bb45a92, 0×5cb36a04, 0xc2d7ffa7, 0xb5d0cf31,
  47. 0×2cd99e8b, 0×5bdeae1d, 0×9b64c2b0, 0xec63f226, 0×756aa39c,
  48. 0×026d930a, 0×9c0906a9, 0xeb0e363f, 0×72076785, 0×05005713,
  49. 0×95bf4a82, 0xe2b87a14, 0×7bb12bae, 0×0cb61b38, 0×92d28e9b,
  50. 0xe5d5be0d, 0×7cdcefb7, 0×0bdbdf21, 0×86d3d2d4, 0xf1d4e242,
  51. 0×68ddb3f8, 0×1fda836e, 0×81be16cd, 0xf6b9265b, 0×6fb077e1,
  52. 0×18b74777, 0×88085ae6, 0xff0f6a70, 0×66063bca, 0×11010b5c,
  53. 0×8f659eff, 0xf862ae69, 0×616bffd3, 0×166ccf45, 0xa00ae278,
  54. 0xd70dd2ee, 0×4e048354, 0×3903b3c2, 0xa7672661, 0xd06016f7,
  55. 0×4969474d, 0×3e6e77db, 0xaed16a4a, 0xd9d65adc, 0×40df0b66,
  56. 0×37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0×47b2cf7f, 0×30b5ffe9,
  57. 0xbdbdf21c, 0xcabac28a, 0×53b39330, 0×24b4a3a6, 0xbad03605,
  58. 0xcdd70693, 0×54de5729, 0×23d967bf, 0xb3667a2e, 0xc4614ab8,
  59. 0×5d681b02, 0×2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0×5a05df1b,
  60. 0×2d02ef8d
  61. };
  63. // The method that does the magic
  64. public static byte[] Calculate(byte[] Value)
  65. {
  66. UInt32 CRCVal = 0xffffffff;
  67. for (int i = 0; i < Value.Length; i++)
  68. {
  69. CRCVal = (CRCVal >> 8) ^ CRCTable[(CRCVal & 0xff) ^ Value[i]];
  70. }
  71. CRCVal ^= 0xffffffff; // Toggle operation
  72. byte[] Result = new byte[4];
  74. Result[0] = (byte)(CRCVal >> 24);
  75. Result[1] = (byte)(CRCVal >> 16);
  76. Result[2] = (byte)(CRCVal >> 8);
  77. Result[3] = (byte)(CRCVal);
  79. return Result;
  80. }