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Diffstat (limited to 'doc/crypto/blowfish.pod')
| -rw-r--r-- | doc/crypto/blowfish.pod | 17 |
1 files changed, 7 insertions, 10 deletions
diff --git a/doc/crypto/blowfish.pod b/doc/crypto/blowfish.pod index 4320af0809d..e8c7114311b 100644 --- a/doc/crypto/blowfish.pod +++ b/doc/crypto/blowfish.pod @@ -28,7 +28,7 @@ BF_cfb64_encrypt, BF_ofb64_encrypt, BF_options - Blowfish encryption =head1 DESCRIPTION This library implements the Blowfish cipher, which is invented and described -by Counterpane (see http://www.counterpane.com/blowfish.html ). +by Counterpane (see http://www.counterpane.com/blowfish/ ). Blowfish is a block cipher that operates on 64 bit (8 byte) blocks of data. It uses a variable size key, but typically, 128 bit (16 byte) keys are @@ -57,31 +57,28 @@ everything after the first 64 bits is ignored. The mode functions BF_cbc_encrypt(), BF_cfb64_encrypt() and BF_ofb64_encrypt() all operate on variable length data. They all take an initialisation vector -B<ivec> which needs to be passed along into the next call of the same function -for the same message. B<ivec> may be initialised with anything, but the -recipient needs to know what it was initialised with, or it won't be able -to decrypt. Some programs and protocols simplify this, like SSH, where -B<ivec> is simply initialised to zero. +B<ivec> which must be initially filled with zeros, but then just need to be +passed along into the next call of the same function for the same message. BF_cbc_encrypt() operates of data that is a multiple of 8 bytes long, while BF_cfb64_encrypt() and BF_ofb64_encrypt() are used to encrypt an variable number of bytes (the amount does not have to be an exact multiple of 8). The purpose of the latter two is to simulate stream ciphers, and therefore, they need the parameter B<num>, which is a pointer to an integer where the current offset in B<ivec> is stored between calls. This integer must be initialised -to zero when B<ivec> is initialised. +to zero when B<ivec> is filled with zeros. BF_cbc_encrypt() is the Cipher Block Chaining function for Blowfish. It encrypts or decrypts the 64 bits chunks of B<in> using the key B<schedule>, putting the result in B<out>. B<enc> decides if encryption (BF_ENCRYPT) or decryption (BF_DECRYPT) shall be performed. B<ivec> must point at an 8 byte -long initialisation vector. +long initialisation vector, which must be initially filled with zeros. BF_cfb64_encrypt() is the CFB mode for Blowfish with 64 bit feedback. It encrypts or decrypts the bytes in B<in> using the key B<schedule>, putting the result in B<out>. B<enc> decides if encryption (B<BF_ENCRYPT>) or decryption (B<BF_DECRYPT>) shall be performed. B<ivec> must point at an -8 byte long initialisation vector. B<num> must point at an integer which must -be initially zero. +8 byte long initialisation vector, which must be initially filled with zeros. +B<num> must point at an integer which must be initially zero. BF_ofb64_encrypt() is the OFB mode for Blowfish with 64 bit feedback. It uses the same parameters as BF_cfb64_encrypt(), which must be initialised |