1=pod
2
3=head1 NAME
4
5blowfish, BF_set_key, BF_encrypt, BF_decrypt, BF_ecb_encrypt, BF_cbc_encrypt,
6BF_cfb64_encrypt, BF_ofb64_encrypt, BF_options - Blowfish encryption
7
8=head1 SYNOPSIS
9
10 #include <openssl/blowfish.h>
11
12 void BF_set_key(BF_KEY *key, int len, const unsigned char *data);
13
14 void BF_ecb_encrypt(const unsigned char *in, unsigned char *out,
15         BF_KEY *key, int enc);
16 void BF_cbc_encrypt(const unsigned char *in, unsigned char *out,
17 	 long length, BF_KEY *schedule, unsigned char *ivec, int enc);
18 void BF_cfb64_encrypt(const unsigned char *in, unsigned char *out,
19 	 long length, BF_KEY *schedule, unsigned char *ivec, int *num,
20         int enc);
21 void BF_ofb64_encrypt(const unsigned char *in, unsigned char *out,
22 	 long length, BF_KEY *schedule, unsigned char *ivec, int *num);
23 const char *BF_options(void);
24
25 void BF_encrypt(BF_LONG *data,const BF_KEY *key);
26 void BF_decrypt(BF_LONG *data,const BF_KEY *key);
27
28=head1 DESCRIPTION
29
30This library implements the Blowfish cipher, which was invented and described
31by Counterpane (see http://www.counterpane.com/blowfish.html ).
32
33Blowfish is a block cipher that operates on 64 bit (8 byte) blocks of data.
34It uses a variable size key, but typically, 128 bit (16 byte) keys are
35considered good for strong encryption.  Blowfish can be used in the same
36modes as DES (see L<des_modes(7)|des_modes(7)>).  Blowfish is currently one
37of the faster block ciphers.  It is quite a bit faster than DES, and much
38faster than IDEA or RC2.
39
40Blowfish consists of a key setup phase and the actual encryption or decryption
41phase.
42
43BF_set_key() sets up the B<BF_KEY> B<key> using the B<len> bytes long key
44at B<data>.
45
46BF_ecb_encrypt() is the basic Blowfish encryption and decryption function.
47It encrypts or decrypts the first 64 bits of B<in> using the key B<key>,
48putting the result in B<out>.  B<enc> decides if encryption (B<BF_ENCRYPT>)
49or decryption (B<BF_DECRYPT>) shall be performed.  The vector pointed at by
50B<in> and B<out> must be 64 bits in length, no less.  If they are larger,
51everything after the first 64 bits is ignored.
52
53The mode functions BF_cbc_encrypt(), BF_cfb64_encrypt() and BF_ofb64_encrypt()
54all operate on variable length data.  They all take an initialization vector
55B<ivec> which needs to be passed along into the next call of the same function
56for the same message.  B<ivec> may be initialized with anything, but the
57recipient needs to know what it was initialized with, or it won't be able
58to decrypt.  Some programs and protocols simplify this, like SSH, where
59B<ivec> is simply initialized to zero.
60BF_cbc_encrypt() operates on data that is a multiple of 8 bytes long, while
61BF_cfb64_encrypt() and BF_ofb64_encrypt() are used to encrypt an variable
62number of bytes (the amount does not have to be an exact multiple of 8).  The
63purpose of the latter two is to simulate stream ciphers, and therefore, they
64need the parameter B<num>, which is a pointer to an integer where the current
65offset in B<ivec> is stored between calls.  This integer must be initialized
66to zero when B<ivec> is initialized.
67
68BF_cbc_encrypt() is the Cipher Block Chaining function for Blowfish.  It
69encrypts or decrypts the 64 bits chunks of B<in> using the key B<schedule>,
70putting the result in B<out>.  B<enc> decides if encryption (BF_ENCRYPT) or
71decryption (BF_DECRYPT) shall be performed.  B<ivec> must point at an 8 byte
72long initialization vector.
73
74BF_cfb64_encrypt() is the CFB mode for Blowfish with 64 bit feedback.
75It encrypts or decrypts the bytes in B<in> using the key B<schedule>,
76putting the result in B<out>.  B<enc> decides if encryption (B<BF_ENCRYPT>)
77or decryption (B<BF_DECRYPT>) shall be performed.  B<ivec> must point at an
788 byte long initialization vector. B<num> must point at an integer which must
79be initially zero.
80
81BF_ofb64_encrypt() is the OFB mode for Blowfish with 64 bit feedback.
82It uses the same parameters as BF_cfb64_encrypt(), which must be initialized
83the same way.
84
85BF_encrypt() and BF_decrypt() are the lowest level functions for Blowfish
86encryption.  They encrypt/decrypt the first 64 bits of the vector pointed by
87B<data>, using the key B<key>.  These functions should not be used unless you
88implement 'modes' of Blowfish.  The alternative is to use BF_ecb_encrypt().
89If you still want to use these functions, you should be aware that they take
90each 32-bit chunk in host-byte order, which is little-endian on little-endian
91platforms and big-endian on big-endian ones.
92
93=head1 RETURN VALUES
94
95None of the functions presented here return any value.
96
97=head1 NOTE
98
99Applications should use the higher level functions
100L<EVP_EncryptInit(3)|EVP_EncryptInit(3)> etc. instead of calling the
101blowfish functions directly.
102
103=head1 SEE ALSO
104
105L<des_modes(7)|des_modes(7)>
106
107=head1 HISTORY
108
109The Blowfish functions are available in all versions of SSLeay and OpenSSL.
110
111=cut
112
113