OpenSL                                        blowfish(3openssl)



NAME
     blowfish, BFsetkey, BFencrypt, BFdecrypt,
     BFecbencrypt, BFcbcencrypt, BFcfb64encrypt,
     BFofb64encrypt, BFoptions - Blowfish encryption

SYNOPSIS
      #include 

      void BFsetkey(BFKEY *key, int len, const unsigned char *data);

      void BFecbencrypt(const unsigned char *in, unsigned char *out,
              BFKEY *key, int enc);
      void BFcbcencrypt(const unsigned char *in, unsigned char *out,
              long length, BFKEY *schedule, unsigned char *ivec, int enc);
      void BFcfb64encrypt(const unsigned char *in, unsigned char *out,
              long length, BFKEY *schedule, unsigned char *ivec, int *num,
              int enc);
      void BFofb64encrypt(const unsigned char *in, unsigned char *out,
              long length, BFKEY *schedule, unsigned char *ivec, int *num);
      const char *BFoptions(void);

      void BFencrypt(BFLONG *data,const BFKEY *key);
      void BFdecrypt(BFLONG *data,const BFKEY *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 considered good for strong
     encryption.  Blowfish can be used in the same modes as DES
     (see desmodes(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.

     BFsetkey() sets up the BFKEY key using the len bytes long
     key at data.

     BFecbencrypt() 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 (BFENCRYPT) or decryption
     (BFDECRYPT) 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.





OpenSL-0.9.8       Last change: Oct 11 2005                    1






OpenSL                                        blowfish(3openssl)



     The mode functions BFcbcencrypt(), BFcfb64encrypt() and
     BFofb64encrypt() 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 SH, where ivec is simply
     initialized to zero.  BFcbcencrypt() operates on data that
     is a multiple of 8 bytes long, while BFcfb64encrypt() and
     BFofb64encrypt() 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.

     BFcbcencrypt() 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 (BFENCRYPT) or decryption
     (BFDECRYPT) shall be performed.  ivec must point at an 8
     byte long initialization vector.

     BFcfb64encrypt() 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 (BFENCRYPT) or decryption (BFDECRYPT) shall be
     performed.  ivec must point at an 8 byte long initialization
     vector. num must point at an integer which must be initially
     zero.

     BFofb64encrypt() is the OFB mode for Blowfish with 64 bit
     feedback.  It uses the same parameters as
     BFcfb64encrypt(), which must be initialized the same way.

     BFencrypt() and BFdecrypt() are the lowest level functions
     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
     BFecbencrypt().  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



OpenSL-0.9.8       Last change: Oct 11 2005                    2






OpenSL                                        blowfish(3openssl)



     EVPEncryptInit(3) etc. instead of calling the blowfish
     functions directly.

SEE ALSO
     desmodes(7)

HISTORY
     The Blowfish functions are available in all versions of
     SLeay and OpenSL.














































OpenSL-0.9.8       Last change: Oct 11 2005                    3