53934822ac
Files like dh.pod, etc., mostly duplicated the API-specific pod files. Removed the duplicated content; that often mean the whole file could be removed. Some of the content about internals got moved into README files in the source tree. Some content (e.g., err.pod) got moved into other pod pages. Annotate generic pages, remove dup NAME Reviewed-by: Richard Levitte <levitte@openssl.org>
117 lines
5 KiB
Text
117 lines
5 KiB
Text
=pod
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=head1 NAME
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BF_set_key, BF_encrypt, BF_decrypt, BF_ecb_encrypt, BF_cbc_encrypt,
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BF_cfb64_encrypt, BF_ofb64_encrypt, BF_options - Blowfish encryption
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=head1 SYNOPSIS
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#include <openssl/blowfish.h>
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void BF_set_key(BF_KEY *key, int len, const unsigned char *data);
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void BF_ecb_encrypt(const unsigned char *in, unsigned char *out,
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BF_KEY *key, int enc);
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void BF_cbc_encrypt(const unsigned char *in, unsigned char *out,
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long length, BF_KEY *schedule, unsigned char *ivec, int enc);
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void BF_cfb64_encrypt(const unsigned char *in, unsigned char *out,
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long length, BF_KEY *schedule, unsigned char *ivec, int *num,
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int enc);
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void BF_ofb64_encrypt(const unsigned char *in, unsigned char *out,
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long length, BF_KEY *schedule, unsigned char *ivec, int *num);
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const char *BF_options(void);
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void BF_encrypt(BF_LONG *data,const BF_KEY *key);
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void BF_decrypt(BF_LONG *data,const BF_KEY *key);
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=head1 DESCRIPTION
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This library implements the Blowfish cipher, which was invented and described
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by Counterpane (see http://www.counterpane.com/blowfish.html ).
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Blowfish is a block cipher that operates on 64 bit (8 byte) blocks of data.
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It uses a variable size key, but typically, 128 bit (16 byte) keys are
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considered good for strong encryption. Blowfish can be used in the same
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modes as DES (see L<des_modes(7)>). Blowfish is currently one
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of the faster block ciphers. It is quite a bit faster than DES, and much
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faster than IDEA or RC2.
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Blowfish consists of a key setup phase and the actual encryption or decryption
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phase.
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BF_set_key() sets up the B<BF_KEY> B<key> using the B<len> bytes long key
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at B<data>.
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BF_ecb_encrypt() is the basic Blowfish encryption and decryption function.
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It encrypts or decrypts the first 64 bits of B<in> using the key B<key>,
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putting the result in B<out>. B<enc> decides if encryption (B<BF_ENCRYPT>)
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or decryption (B<BF_DECRYPT>) shall be performed. The vector pointed at by
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B<in> and B<out> must be 64 bits in length, no less. If they are larger,
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everything after the first 64 bits is ignored.
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The mode functions BF_cbc_encrypt(), BF_cfb64_encrypt() and BF_ofb64_encrypt()
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all operate on variable length data. They all take an initialization vector
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B<ivec> which needs to be passed along into the next call of the same function
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for the same message. B<ivec> may be initialized with anything, but the
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recipient needs to know what it was initialized with, or it won't be able
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to decrypt. Some programs and protocols simplify this, like SSH, where
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B<ivec> is simply initialized to zero.
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BF_cbc_encrypt() operates on data that is a multiple of 8 bytes long, while
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BF_cfb64_encrypt() and BF_ofb64_encrypt() are used to encrypt an variable
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number of bytes (the amount does not have to be an exact multiple of 8). The
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purpose of the latter two is to simulate stream ciphers, and therefore, they
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need the parameter B<num>, which is a pointer to an integer where the current
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offset in B<ivec> is stored between calls. This integer must be initialized
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to zero when B<ivec> is initialized.
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BF_cbc_encrypt() is the Cipher Block Chaining function for Blowfish. It
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encrypts or decrypts the 64 bits chunks of B<in> using the key B<schedule>,
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putting the result in B<out>. B<enc> decides if encryption (BF_ENCRYPT) or
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decryption (BF_DECRYPT) shall be performed. B<ivec> must point at an 8 byte
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long initialization vector.
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BF_cfb64_encrypt() is the CFB mode for Blowfish with 64 bit feedback.
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It encrypts or decrypts the bytes in B<in> using the key B<schedule>,
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putting the result in B<out>. B<enc> decides if encryption (B<BF_ENCRYPT>)
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or decryption (B<BF_DECRYPT>) shall be performed. B<ivec> must point at an
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8 byte long initialization vector. B<num> must point at an integer which must
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be initially zero.
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BF_ofb64_encrypt() is the OFB mode for Blowfish with 64 bit feedback.
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It uses the same parameters as BF_cfb64_encrypt(), which must be initialized
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the same way.
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BF_encrypt() and BF_decrypt() are the lowest level functions for Blowfish
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encryption. They encrypt/decrypt the first 64 bits of the vector pointed by
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B<data>, using the key B<key>. These functions should not be used unless you
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implement 'modes' of Blowfish. The alternative is to use BF_ecb_encrypt().
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If you still want to use these functions, you should be aware that they take
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each 32-bit chunk in host-byte order, which is little-endian on little-endian
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platforms and big-endian on big-endian ones.
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=head1 RETURN VALUES
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None of the functions presented here return any value.
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=head1 NOTE
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Applications should use the higher level functions
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L<EVP_EncryptInit(3)> etc. instead of calling these
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functions directly.
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=head1 SEE ALSO
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L<EVP_EncryptInit(3)>,
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L<des_modes(7)>
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=head1 COPYRIGHT
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Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the OpenSSL license (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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