blowfish(3)

     blowfish(3)            0.9.6h (2002-01-21)            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 decryption
          (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

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          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 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
          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

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     blowfish(3)            0.9.6h (2002-01-21)            blowfish(3)

          functions directly.

     SEE ALSO
          des_modes(7)

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

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