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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 is
     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
     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 of 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
     functions directly.



SEE ALSO
     des_modes(7)



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









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Created 1996-2024 by Maxim Chirkov

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