BF_encrypt.pod 5.1 KB

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  1. =pod
  2. =head1 NAME
  3. BF_set_key, BF_encrypt, BF_decrypt, BF_ecb_encrypt, BF_cbc_encrypt,
  4. BF_cfb64_encrypt, BF_ofb64_encrypt, BF_options - Blowfish encryption
  5. =head1 SYNOPSIS
  6. #include <openssl/blowfish.h>
  7. void BF_set_key(BF_KEY *key, int len, const unsigned char *data);
  8. void BF_ecb_encrypt(const unsigned char *in, unsigned char *out,
  9. BF_KEY *key, int enc);
  10. void BF_cbc_encrypt(const unsigned char *in, unsigned char *out,
  11. long length, BF_KEY *schedule,
  12. unsigned char *ivec, int enc);
  13. void BF_cfb64_encrypt(const unsigned char *in, unsigned char *out,
  14. long length, BF_KEY *schedule,
  15. unsigned char *ivec, int *num, int enc);
  16. void BF_ofb64_encrypt(const unsigned char *in, unsigned char *out,
  17. long length, BF_KEY *schedule,
  18. unsigned char *ivec, int *num);
  19. const char *BF_options(void);
  20. void BF_encrypt(BF_LONG *data, const BF_KEY *key);
  21. void BF_decrypt(BF_LONG *data, const BF_KEY *key);
  22. =head1 DESCRIPTION
  23. This library implements the Blowfish cipher, which was invented and described
  24. by Counterpane (see http://www.counterpane.com/blowfish.html ).
  25. Blowfish is a block cipher that operates on 64 bit (8 byte) blocks of data.
  26. It uses a variable size key, but typically, 128 bit (16 byte) keys are
  27. considered good for strong encryption. Blowfish can be used in the same
  28. modes as DES (see L<des_modes(7)>). Blowfish is currently one
  29. of the faster block ciphers. It is quite a bit faster than DES, and much
  30. faster than IDEA or RC2.
  31. Blowfish consists of a key setup phase and the actual encryption or decryption
  32. phase.
  33. BF_set_key() sets up the B<BF_KEY> B<key> using the B<len> bytes long key
  34. at B<data>.
  35. BF_ecb_encrypt() is the basic Blowfish encryption and decryption function.
  36. It encrypts or decrypts the first 64 bits of B<in> using the key B<key>,
  37. putting the result in B<out>. B<enc> decides if encryption (B<BF_ENCRYPT>)
  38. or decryption (B<BF_DECRYPT>) shall be performed. The vector pointed at by
  39. B<in> and B<out> must be 64 bits in length, no less. If they are larger,
  40. everything after the first 64 bits is ignored.
  41. The mode functions BF_cbc_encrypt(), BF_cfb64_encrypt() and BF_ofb64_encrypt()
  42. all operate on variable length data. They all take an initialization vector
  43. B<ivec> which needs to be passed along into the next call of the same function
  44. for the same message. B<ivec> may be initialized with anything, but the
  45. recipient needs to know what it was initialized with, or it won't be able
  46. to decrypt. Some programs and protocols simplify this, like SSH, where
  47. B<ivec> is simply initialized to zero.
  48. BF_cbc_encrypt() operates on data that is a multiple of 8 bytes long, while
  49. BF_cfb64_encrypt() and BF_ofb64_encrypt() are used to encrypt an variable
  50. number of bytes (the amount does not have to be an exact multiple of 8). The
  51. purpose of the latter two is to simulate stream ciphers, and therefore, they
  52. need the parameter B<num>, which is a pointer to an integer where the current
  53. offset in B<ivec> is stored between calls. This integer must be initialized
  54. to zero when B<ivec> is initialized.
  55. BF_cbc_encrypt() is the Cipher Block Chaining function for Blowfish. It
  56. encrypts or decrypts the 64 bits chunks of B<in> using the key B<schedule>,
  57. putting the result in B<out>. B<enc> decides if encryption (BF_ENCRYPT) or
  58. decryption (BF_DECRYPT) shall be performed. B<ivec> must point at an 8 byte
  59. long initialization vector.
  60. BF_cfb64_encrypt() is the CFB mode for Blowfish with 64 bit feedback.
  61. It encrypts or decrypts the bytes in B<in> using the key B<schedule>,
  62. putting the result in B<out>. B<enc> decides if encryption (B<BF_ENCRYPT>)
  63. or decryption (B<BF_DECRYPT>) shall be performed. B<ivec> must point at an
  64. 8 byte long initialization vector. B<num> must point at an integer which must
  65. be initially zero.
  66. BF_ofb64_encrypt() is the OFB mode for Blowfish with 64 bit feedback.
  67. It uses the same parameters as BF_cfb64_encrypt(), which must be initialized
  68. the same way.
  69. BF_encrypt() and BF_decrypt() are the lowest level functions for Blowfish
  70. encryption. They encrypt/decrypt the first 64 bits of the vector pointed by
  71. B<data>, using the key B<key>. These functions should not be used unless you
  72. implement 'modes' of Blowfish. The alternative is to use BF_ecb_encrypt().
  73. If you still want to use these functions, you should be aware that they take
  74. each 32-bit chunk in host-byte order, which is little-endian on little-endian
  75. platforms and big-endian on big-endian ones.
  76. =head1 RETURN VALUES
  77. None of the functions presented here return any value.
  78. =head1 NOTE
  79. Applications should use the higher level functions
  80. L<EVP_EncryptInit(3)> etc. instead of calling these
  81. functions directly.
  82. =head1 SEE ALSO
  83. L<EVP_EncryptInit(3)>,
  84. L<des_modes(7)>
  85. =head1 COPYRIGHT
  86. Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
  87. Licensed under the OpenSSL license (the "License"). You may not use
  88. this file except in compliance with the License. You can obtain a copy
  89. in the file LICENSE in the source distribution or at
  90. L<https://www.openssl.org/source/license.html>.
  91. =cut