1
0

encrypt 1.8 KB

12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667686970717273747576
  1. .TH ENCRYPT 2
  2. .SH NAME
  3. encrypt, decrypt, netcrypt \- DES encryption
  4. .SH SYNOPSIS
  5. .B #include <u.h>
  6. .br
  7. .B #include <libc.h>
  8. .PP
  9. .B
  10. int encrypt(void *key, void *data, int len)
  11. .PP
  12. .B
  13. int decrypt(void *key, void *data, int len)
  14. .PP
  15. .B
  16. int netcrypt(void *key, void *data)
  17. .SH DESCRIPTION
  18. .I Encrypt
  19. and
  20. .I decrypt
  21. perform DES encryption and decryption.
  22. .I Key
  23. is an array of
  24. .B DESKEYLEN
  25. (defined as 7 in
  26. .BR <auth.h> )
  27. bytes containing the encryption key.
  28. .I Data
  29. is an array of
  30. .I len
  31. bytes;
  32. it must be at least 8 bytes long.
  33. The bytes are encrypted or decrypted in place.
  34. .PP
  35. The DES algorithm encrypts an individual 8-byte block of data.
  36. .I Encrypt
  37. uses the following method to encrypt data longer than 8 bytes.
  38. The first 8 bytes are encrypted as usual.
  39. The last byte of the encrypted result
  40. is prefixed to the next 7 unencrypted bytes to make the next 8
  41. bytes to encrypt.
  42. This is repeated until fewer than 7 bytes remain unencrypted.
  43. Any remaining unencrypted bytes are encrypted with enough of the preceding
  44. encrypted bytes to make a full 8-byte block.
  45. .I Decrypt
  46. uses the inverse algorithm.
  47. .PP
  48. .I Netcrypt
  49. performs the same encryption as a SecureNet Key.
  50. .I Data
  51. points to an
  52. .SM ASCII
  53. string of decimal digits with numeric value between 0 and 10000.
  54. These digits are copied into an 8-byte buffer with trailing binary zero fill
  55. and encrypted as one DES block.
  56. The first four bytes are each formatted as two digit
  57. .SM ASCII
  58. hexadecimal numbers,
  59. and the string is copied into
  60. .IR data .
  61. .SH SOURCE
  62. .B /sys/src/libc/port
  63. .SH DIAGNOSTICS
  64. These routines return 1 if the data was encrypted,
  65. and 0 if the encryption fails.
  66. .I Encrypt
  67. and
  68. .I decrypt
  69. fail if the data passed is less than 8 bytes long.
  70. .I Netcrypt
  71. can fail if it is passed invalid data.
  72. .SH SEE ALSO
  73. .IR securenet (8)
  74. .SH BUGS
  75. The implementation is broken in a way that makes
  76. it unsuitable for anything but authentication.