blowfish(3)                 OpenSSL                 blowfish(3)





NAME
       blowfish, BF_set_key, BF_encrypt, BF_decrypt,
       BF_ecb_encrypt, BF_cbc_encrypt, BF_cfb64_encrypt,
       BF_ofb64_encrypt, BF_options - Blowfish encryption

SYNOPSIS
        #include <openssl/blowfish.h>

        void BF_set_key(BF_KEY *key, int len, const unsigned char *data);

        void BF_ecb_encrypt(const unsigned char *in, unsigned char *out,
                BF_KEY *key, int enc);
        void BF_cbc_encrypt(const unsigned char *in, unsigned char *out,
                long length, BF_KEY *schedule, unsigned char *ivec, int enc);
        void BF_cfb64_encrypt(const unsigned char *in, unsigned char *out,
                long length, BF_KEY *schedule, unsigned char *ivec, int *num,
                int enc);
        void BF_ofb64_encrypt(const unsigned char *in, unsigned char *out,
                long length, BF_KEY *schedule, unsigned char *ivec, int *num);
        const char *BF_options(void);

        void BF_encrypt(BF_LONG *data,const BF_KEY *key);
        void BF_decrypt(BF_LONG *data,const BF_KEY *key);

DESCRIPTION
       This library implements the Blowfish cipher, which was
       invented and described by Counterpane (see
       http://www.counterpane.com/blowfish.html ).

       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 a considered good
       for strong encryption.  Blowfish can be used in the same
       modes as DES (see des_modes(7)).  Blowfish is currently
       one of the faster block ciphers.  It is quite a bit
       faster than DES, and much faster than IDEA or RC2.

       Blowfish consists of a key setup phase and the actual
       encryption or decryption phase.

       BF_set_key() sets up the BF_KEY key using the len bytes
       long key at data.

       BF_ecb_encrypt() is the basic Blowfish encryption and
       decryption function.  It encrypts or decrypts the first
       64 bits of in using the key key, putting the result in
       out.  enc decides if encryption (BF_ENCRYPT) or decryp-
       tion (BF_DECRYPT) shall be performed.  The vector
       pointed at by in and out must be 64 bits in length, no
       less.  If they are larger, 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 initialization vector ivec which
       needs to be passed along into the next call of the same
       function for the same message.  ivec may be initialized
       with anything, but the recipient needs to know what it
       was initialized with, or it won't be able to decrypt.
       Some programs and protocols simplify this, like SSH,
       where ivec is simply initialized to zero.
       BF_cbc_encrypt() operates on 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 num, which is a pointer to an integer where
       the current offset in ivec is stored between calls.
       This integer must be initialized to zero when ivec is
       initialized.

       BF_cbc_encrypt() is the Cipher Block Chaining function
       for Blowfish.  It encrypts or decrypts the 64 bits
       chunks of in using the key schedule, putting the result
       in out.  enc decides if encryption (BF_ENCRYPT) or
       decryption (BF_DECRYPT) shall be performed.  ivec must
       point at an 8 byte long initialization vector.

       BF_cfb64_encrypt() is the CFB mode for Blowfish with 64
       bit feedback.  It encrypts or decrypts the bytes in in
       using the key schedule, putting the result in out.  enc
       decides if encryption (BF_ENCRYPT) or decryption
       (BF_DECRYPT) shall be performed.  ivec must point at an
       8 byte long initialization vector. 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 initialized the same
       way.

       BF_encrypt() and BF_decrypt() are the lowest level func-
       tions for Blowfish encryption.  They encrypt/decrypt the
       first 64 bits of the vector pointed by data, using the
       key key.  These functions should not be used unless you
       implement 'modes' of Blowfish.  The alternative is to
       use BF_ecb_encrypt().  If you still want to use these
       functions, you should be aware that they take each
       32-bit chunk in host-byte order, which is little-endian
       on little-endian platforms and big-endian on big-endian
       ones.

RETURN VALUES
       None of the functions presented here return any value.

NOTE
       Applications should use the higher level functions
       EVP_EncryptInit(3) etc. instead of calling the blowfish
       functions directly.

SEE ALSO
       des_modes(7)

HISTORY
       The Blowfish functions are available in all versions of
       SSLeay and OpenSSL.



0.9.7c                     2002-01-21               blowfish(3)
