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

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

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

  The BF_ecb_encrypt() function 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.  The 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 BF_cbc_encrypt(), BF_cfb64_encrypt(), and BF_ofb64_encrypt() mode
  functions 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.  The ivec may be
  initialized with anything, but the recipient needs to know what was used,
  or it won't be able to decrypt.  Some programs and protocols simplify this.
  For example, ivec is simply initialized to zero in SSH. The
  BF_cbc_encrypt() function operates of data that is a multiple of 8 bytes
  long, while the BF_cfb64_encrypt() and BF_ofb64_encrypt() functions are
  used to encrypt a 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.

  The BF_cbc_encrypt() function 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.	The enc decides if encryption
  (BF_ENCRYPT) or decryption (BF_DECRYPT) shall be performed.  The ivec must
  point at an 8 byte long initialization vector.

  The BF_cfb64_encrypt() function 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.  The enc decides if encryption (BF_ENCRYPT) or
  decryption (BF_DECRYPT) shall be performed.  The ivec must point at an 8
  byte long initialization vector. The num must point at an integer which
  must be initially zero.

  The BF_ofb64_encrypt() function is the OFB mode for Blowfish with 64-bit
  feedback. It uses the same parameters as the BF_cfb64_encrypt() function,
  which must be initialized the same way.

  The BF_encrypt() and BF_decrypt() functions are the lowest level functions
  for Blowfish encryption.  They encrypt or decrypt the first 64 bits of the
  vector pointed by data, using the key key.  They also take each 32-bit
  chunk in host-byte order, which is little-endian on little-endian platforms
  and big-endian on big-endian platforms. These functions should not be used
  unless you implement modes of Blowfish.  The alternative is to use the
  BF_ecb_encrypt() function.


NOTES

  Applications should use the higher level functions, such as
  EVP_EncryptInit(), instead of calling the blowfish functions directly.


RETURN VALUES

  None of the functions presented here return any value.


HISTORY

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


SEE ALSO

  Files: des_modes(7)

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