=pod=head1 NAMEblowfish, BF_set_key, BF_encrypt, BF_decrypt, BF_ecb_encrypt, BF_cbc_encrypt,BF_cfb64_encrypt, BF_ofb64_encrypt, BF_options - Blowfish encryption=head1 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);=head1 DESCRIPTIONThis library implements the Blowfish cipher, which is invented and describedby 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 area considered good for strong encryption.  Blowfish can be used in the samemodes as DES (see L<des_modes(7)|des_modes(7)>).  Blowfish is currently oneof the faster block ciphers.  It is quite a bit faster than DES, and muchfaster than IDEA or RC2.Blowfish consists of a key setup phase and the actual encryption or decryptionphase.BF_set_key() sets up the B<BF_KEY> B<key> using the B<len> bytes long keyat B<data>.BF_ecb_encrypt() is the basic Blowfish encryption and decryption function.It encrypts or decrypts the first 64 bits of B<in> using the key B<key>,putting the result in B<out>.  B<enc> decides if encryption (B<BF_ENCRYPT>)or decryption (B<BF_DECRYPT>) shall be performed.  The vector pointed at byB<in> and B<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 vectorB<ivec> which needs to be passed along into the next call of the same function for the same message.  B<ivec> may be initialized with anything, but therecipient needs to know what it was initialized with, or it won't be ableto decrypt.  Some programs and protocols simplify this, like SSH, whereB<ivec> is simply initialized to zero.BF_cbc_encrypt() operates of data that is a multiple of 8 bytes long, whileBF_cfb64_encrypt() and BF_ofb64_encrypt() are used to encrypt an variablenumber of bytes (the amount does not have to be an exact multiple of 8).  Thepurpose of the latter two is to simulate stream ciphers, and therefore, theyneed the parameter B<num>, which is a pointer to an integer where the currentoffset in B<ivec> is stored between calls.  This integer must be initializedto zero when B<ivec> is initialized.BF_cbc_encrypt() is the Cipher Block Chaining function for Blowfish.  Itencrypts or decrypts the 64 bits chunks of B<in> using the key B<schedule>,putting the result in B<out>.  B<enc> decides if encryption (BF_ENCRYPT) ordecryption (BF_DECRYPT) shall be performed.  B<ivec> must point at an 8 bytelong initialization vector.BF_cfb64_encrypt() is the CFB mode for Blowfish with 64 bit feedback.It encrypts or decrypts the bytes in B<in> using the key B<schedule>,putting the result in B<out>.  B<enc> decides if encryption (B<BF_ENCRYPT>)or decryption (B<BF_DECRYPT>) shall be performed.  B<ivec> must point at an8 byte long initialization vector. B<num> must point at an integer which mustbe 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 initializedthe same way.BF_encrypt() and BF_decrypt() are the lowest level functions for Blowfishencryption.  They encrypt/decrypt the first 64 bits of the vector pointed byB<data>, using the key B<key>.  These functions should not be used unless youimplement '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 takeeach 32-bit chunk in host-byte order, which is little-endian on little-endianplatforms and big-endian on big-endian ones.=head1 RETURN VALUESNone of the functions presented here return any value.=head1 NOTEApplications should use the higher level functionsL<EVP_EncryptInit(3)|EVP_EncryptInit(3)> etc. instead of calling theblowfish functions directly.=head1 SEE ALSOL<des_modes(7)|des_modes(7)>=head1 HISTORYThe Blowfish functions are available in all versions of SSLeay and OpenSSL.=cut