Crypt::...::CAST5(3)

🦋 Crypt::...::CAST5(3) 🦋

okay so real talk: this page is from the User Contributed Perl Documentation (manual section 3), and the actual module it’s hyping up is Crypt::Cipher::CAST5. the vibe is iconic, no cap.

✨ NAME ✨

Crypt::Cipher::CAST5 — Symmetric cipher CAST5 (aka CAST-128), key size: 40-128 bits

🎀 SYNOPSIS 🎀

bestie, here are the two usage routes. example 1 is the Crypt::Mode::CBC way, example 2 is the Crypt::CBC way (and yes, it’s marked slower). both are valid, one is just more lowkey.

### example 1
use Crypt::Mode::CBC;

my $key = '...'; # length must be a valid key size for this cipher
my $iv = '...';  # 16 bytes
my $cbc = Crypt::Mode::CBC->new('CAST5');
my $ciphertext = $cbc->encrypt("secret data", $key, $iv);

### example 2 (slower)
use Crypt::CBC;
use Crypt::Cipher::CAST5;

my $key = '...'; # length must be a valid key size for this cipher
my $iv = '...';  # 16 bytes
my $cbc = Crypt::CBC->new( -cipher=>'Cipher::CAST5', -key=>$key, -iv=>$iv );
my $ciphertext = $cbc->encrypt("secret data");

💜 DESCRIPTION 💜

This module implements the CAST5 cipher. Its interface is compatible with Crypt::CBC.

⚠️ note, bestie: This module only implements single-block encryption and decryption. For general data, use a block mode such as Crypt::Mode::CBC, Crypt::Mode::CTR, or Crypt::CBC (which is slower).

🌸 METHODS 🌸

Unless noted otherwise, assume $c is an existing cipher object created via new, for example:

my $c = Crypt::Cipher::CAST5->new($key);

🎀 new 🎀

Make a fresh cipher object. You can pass just a key, or a key plus optional rounds.

my $c = Crypt::Cipher::CAST5->new($key);
#or
my $c = Crypt::Cipher::CAST5->new($key, $rounds);

# $key .... [binary string] key of an accepted length (see keysize, min_keysize, max_keysize)
# $rounds . [integer] optional, number of rounds (if supported by the cipher; croaks on invalid value)

🔥 encrypt 🔥

Encrypts exactly one block of plaintext. The length of $plaintext must equal blocksize; croaks otherwise. An empty string is accepted and returned unchanged.

my $ciphertext = $c->encrypt($plaintext);

Returns the encrypted block as a binary string (raw bytes). periodt.

💜 decrypt 💜

Decrypts exactly one block of ciphertext. The length of $ciphertext must equal blocksize; croaks otherwise. An empty string is accepted and returned unchanged.

my $plaintext = $c->decrypt($ciphertext);

Returns the decrypted block as a binary string (raw bytes).

⭐ keysize ⭐

Just an alias for max_keysize.

$c->keysize;
#or
Crypt::Cipher::CAST5->keysize;
#or
Crypt::Cipher::CAST5::keysize;

🦋 blocksize 🦋

Returns the cipher block size (in bytes).

$c->blocksize;
#or
Crypt::Cipher::CAST5->blocksize;
#or
Crypt::Cipher::CAST5::blocksize;

🌸 max_keysize 🌸

Returns the maximum key size (in bytes).

$c->max_keysize;
#or
Crypt::Cipher::CAST5->max_keysize;
#or
Crypt::Cipher::CAST5::max_keysize;

🎀 min_keysize 🎀

Returns the minimum key size (in bytes).

$c->min_keysize;
#or
Crypt::Cipher::CAST5->min_keysize;
#or
Crypt::Cipher::CAST5::min_keysize;

✨ default_rounds ✨

Returns the cipher's default round count.

$c->default_rounds;
#or
Crypt::Cipher::CAST5->default_rounds;
#or
Crypt::Cipher::CAST5::default_rounds;

🫶 SEE ALSO 🫶

• CryptX, Crypt::Cipher
• <https://en.wikipedia.org/wiki/CAST-128>

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mwah 💋 before you go: the footer tea is perl v5.42.0, dated 2026-05-11, and the source/header is Crypt::...::CAST5(3). bye bestie, go encrypt something iconic 🫶✨