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.IX Title "Blowfish 3"
.TH Blowfish 3 2023-07-25 "perl v5.38.0" "User Contributed Perl Documentation"
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.\" way too many mistakes in technical documents.
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.SH NAME
Crypt::Blowfish \- Perl Blowfish encryption module
.SH SYNOPSIS
.IX Header "SYNOPSIS"
.Vb 4
\&  use Crypt::Blowfish;
\&  my $cipher = new Crypt::Blowfish $key; 
\&  my $ciphertext = $cipher\->encrypt($plaintext);
\&  my $plaintext  = $cipher\->decrypt($ciphertext);
\&
\&  You probably want to use this in conjunction with 
\&  a block chaining module like Crypt::CBC.
.Ve
.SH DESCRIPTION
.IX Header "DESCRIPTION"
Blowfish is capable of strong encryption and can use key sizes up
to 56 bytes (a 448 bit key).  You're encouraged to take advantage
of the full key size to ensure the strongest encryption possible
from this module.
.PP
Crypt::Blowfish has the following methods:
.Sp
.Vb 4
\& blocksize()
\& keysize()
\& encrypt()
\& decrypt()
.Ve
.SH FUNCTIONS
.IX Header "FUNCTIONS"
.IP blocksize 4
.IX Item "blocksize"
Returns the size (in bytes) of the block cipher.
.Sp
Crypt::Blowfish doesn't return a key size due to its ability
to use variable-length keys.  More accurately, it shouldn't,
but it does anyway to play nicely with others.
.IP new 4
.IX Item "new"
.Vb 1
\&        my $cipher = new Crypt::Blowfish $key;
.Ve
.Sp
This creates a new Crypt::Blowfish BlockCipher object, using \f(CW$key\fR,
where \f(CW$key\fR is a key of \f(CWkeysize()\fR bytes (minimum of eight bytes).
.IP encrypt 4
.IX Item "encrypt"
.Vb 2
\&        my $cipher = new Crypt::Blowfish $key;
\&        my $ciphertext = $cipher\->encrypt($plaintext);
.Ve
.Sp
This function encrypts \f(CW$plaintext\fR and returns the \f(CW$ciphertext\fR
where \f(CW$plaintext\fR and \f(CW$ciphertext\fR must be of \f(CWblocksize()\fR bytes.
(hint:  Blowfish is an 8 byte block cipher)
.IP decrypt 4
.IX Item "decrypt"
.Vb 2
\&        my $cipher = new Crypt::Blowfish $key;
\&        my $plaintext = $cipher\->decrypt($ciphertext);
.Ve
.Sp
This function decrypts \f(CW$ciphertext\fR and returns the \f(CW$plaintext\fR
where \f(CW$plaintext\fR and \f(CW$ciphertext\fR must be of \f(CWblocksize()\fR bytes.
(hint:  see previous hint)
.SH EXAMPLE
.IX Header "EXAMPLE"
.Vb 4
\&        my $key = pack("H16", "0123456789ABCDEF");  # min. 8 bytes
\&        my $cipher = new Crypt::Blowfish $key;
\&        my $ciphertext = $cipher\->encrypt("plaintex");  # SEE NOTES 
\&        print unpack("H16", $ciphertext), "\en";
.Ve
.SH PLATFORMS
.IX Header "PLATFORMS"
.Vb 2
\&        Please see the README document for platforms and performance
\&        tests.
.Ve
.SH NOTES
.IX Header "NOTES"
The module is capable of being used with Crypt::CBC.  You're
encouraged to read the perldoc for Crypt::CBC if you intend to
use this module for Cipher Block Chaining modes.  In fact, if
you have any intentions of encrypting more than eight bytes of
data with this, or any other block cipher, you're going to need
\&\fBsome\fR type of block chaining help.  Crypt::CBC tends to be
very good at this.  If you're not going to encrypt more than 
eight bytes, your data \fBmust\fR be \fBexactly\fR eight bytes long.
If need be, do your own padding. "\e0" as a null byte is perfectly
valid to use for this.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
Crypt::CBC,
Crypt::DES,
Crypt::IDEA
.PP
Bruce Schneier, \fIApplied Cryptography\fR, 1995, Second Edition,
published by John Wiley & Sons, Inc.
.SH COPYRIGHT
.IX Header "COPYRIGHT"
The implementation of the Blowfish algorithm was developed by,
and is copyright of, A.M. Kuchling.
.PP
Other parts of the perl extension and module are
copyright of Systemics Ltd ( http://www.systemics.com/ ).
.PP
Code revisions, updates, and standalone release are copyright
1999\-2010 W3Works, LLC.
.SH AUTHOR
.IX Header "AUTHOR"
Original algorithm, Bruce Shneier.  Original implementation, A.M.
Kuchling.  Original Perl implementation, Systemics Ltd.  Current
maintenance by W3Works, LLC.
.PP
Current revision and maintainer:  Dave Paris <amused@pobox.com>