Blowfish(3) User Contributed Perl Documentation Blowfish(3)

Crypt::Blowfish - Perl Blowfish encryption module

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.

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.

Crypt::Blowfish has the following methods:


Returns the size (in bytes) of the block cipher.

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.

my $cipher = new Crypt::Blowfish $key;

This creates a new Crypt::Blowfish BlockCipher object, using $key, where $key is a key of keysize() bytes (minimum of eight bytes).

my $cipher = new Crypt::Blowfish $key;
my $ciphertext = $cipher->encrypt($plaintext);

This function encrypts $plaintext and returns the $ciphertext where $plaintext and $ciphertext must be of blocksize() bytes. (hint: Blowfish is an 8 byte block cipher)

my $cipher = new Crypt::Blowfish $key;
my $plaintext = $cipher->decrypt($ciphertext);

This function decrypts $ciphertext and returns the $plaintext where $plaintext and $ciphertext must be of blocksize() bytes. (hint: see previous hint)

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), "\n";

Please see the README document for platforms and performance

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 some 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 must be exactly eight bytes long. If need be, do your own padding. "\0" as a null byte is perfectly valid to use for this.

Crypt::CBC, Crypt::DES, Crypt::IDEA

Bruce Schneier, Applied Cryptography, 1995, Second Edition, published by John Wiley & Sons, Inc.

The implementation of the Blowfish algorithm was developed by, and is copyright of, A.M. Kuchling.

Other parts of the perl extension and module are copyright of Systemics Ltd ( ).

Code revisions, updates, and standalone release are copyright 1999-2010 W3Works, LLC.

Original algorithm, Bruce Shneier. Original implementation, A.M. Kuchling. Original Perl implementation, Systemics Ltd. Current maintenance by W3Works, LLC.

Current revision and maintainer: Dave Paris <>

2023-07-25 perl v5.38.0