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.IX Title "Crypt::Cipher 3"
.TH Crypt::Cipher 3 2026-08-10 "perl v5.42.2" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
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.SH NAME
Crypt::Cipher \- Generic interface to cipher functions
.SH SYNOPSIS
.IX Header "SYNOPSIS"
.Vb 2
\&   #### example 1 (encrypting single block)
\&   use Crypt::Cipher;
\&
\&   my $key = \*(Aq1234567890abcdef\*(Aq; # 16 bytes, valid for AES\-128
\&   my $plaintext_block = \*(Aq1234567890123456\*(Aq; # one AES block (16 bytes)
\&   my $c = Crypt::Cipher\->new(\*(AqAES\*(Aq, $key);
\&   my $blocksize  = $c\->blocksize;
\&   my $ciphertext = $c\->encrypt($plaintext_block);   # encrypt 1 block
\&   my $plaintext  = $c\->decrypt($ciphertext);         #decrypt 1 block
\&
\&   ### example 2 (using CBC mode)
\&   use Crypt::Mode::CBC;
\&
\&   my $cbc_key = \*(Aq1234567890abcdef\*(Aq; # 16 bytes, valid for AES\-128
\&   my $iv = \*(Aqfedcba0987654321\*(Aq;      # 16 bytes
\&   my $cbc = Crypt::Mode::CBC\->new(\*(AqAES\*(Aq);
\&   my $cbc_ciphertext = $cbc\->encrypt("secret data", $cbc_key, $iv);
\&
\&   #### example 3 (compatibility with Crypt::CBC)
\&   use Crypt::CBC;
\&   use Crypt::Cipher;
\&
\&   my $compat_key = \*(Aq1234567890abcdef\*(Aq; # 16 bytes, valid for AES\-128
\&   my $compat_iv = \*(Aqfedcba0987654321\*(Aq;  # 16 bytes
\&   my $cipher = Crypt::Cipher\->new(\*(AqAES\*(Aq, $compat_key);
\&   my $compat_cbc = Crypt::CBC\->new( \-cipher=>$cipher, \-iv=>$compat_iv );
\&   my $compat_ciphertext = $compat_cbc\->encrypt("secret data");
.Ve
.SH DESCRIPTION
.IX Header "DESCRIPTION"
Provides an interface to various symmetric cipher algorithms.
.PP
\&\fBNote:\fR This module only implements single\-block encryption and decryption.
For general data, use a block mode such as
Crypt::Mode::CBC, Crypt::Mode::CTR, or Crypt::CBC (which is slower).
.SH METHODS
.IX Header "METHODS"
Unless noted otherwise, assume \f(CW$c\fR is an existing cipher object created via
\&\f(CW\*(C`new\*(C'\fR, for example:
.PP
.Vb 1
\& my $c = Crypt::Cipher\->new(\*(AqAES\*(Aq, \*(Aq1234567890abcdef\*(Aq);
.Ve
.SS new
.IX Subsection "new"
Constructor. Returns a reference to the cipher object.
.PP
.Vb 8
\& ## basic scenario
\& my $c = Crypt::Cipher\->new($name, $key);
\& # $name = one of \*(AqAES\*(Aq, \*(AqAnubis\*(Aq, \*(AqBlowfish\*(Aq, \*(AqCAST5\*(Aq, \*(AqCamellia\*(Aq, \*(AqDES\*(Aq, \*(AqDES_EDE\*(Aq,
\& #                \*(AqKASUMI\*(Aq, \*(AqKhazad\*(Aq, \*(AqMULTI2\*(Aq, \*(AqNoekeon\*(Aq, \*(AqRC2\*(Aq, \*(AqRC5\*(Aq, \*(AqRC6\*(Aq,
\& #                \*(AqSAFERP\*(Aq, \*(AqSAFER_K128\*(Aq, \*(AqSAFER_K64\*(Aq, \*(AqSAFER_SK128\*(Aq, \*(AqSAFER_SK64\*(Aq,
\& #                \*(AqSEED\*(Aq, \*(AqSM4\*(Aq, \*(AqSkipjack\*(Aq, \*(AqTwofish\*(Aq, \*(AqXTEA\*(Aq, \*(AqIDEA\*(Aq, \*(AqSerpent\*(Aq
\& #                or any <NAME> for which there is a Crypt::Cipher::<NAME> module
\& # $key = binary key (keysize should comply with selected cipher requirements)
\&
\& ## some of the ciphers (e.g. MULTI2, RC5, SAFER) allow one to set number of rounds
\& my $c = Crypt::Cipher\->new(\*(AqMULTI2\*(Aq, $key, $rounds);
\& # $rounds = positive integer (should comply with selected cipher requirements)
.Ve
.SS encrypt
.IX Subsection "encrypt"
Encrypts \f(CW$plaintext\fR and returns \f(CW$ciphertext\fR. An empty string is
accepted and returned unchanged; otherwise \f(CW$plaintext\fR must be exactly
\&\fBblocksize\fR bytes long.
.PP
.Vb 1
\& my $ciphertext = $c\->encrypt($plaintext);
.Ve
.SS decrypt
.IX Subsection "decrypt"
Decrypts \f(CW$ciphertext\fR and returns \f(CW$plaintext\fR. An empty string is
accepted and returned unchanged; otherwise \f(CW$ciphertext\fR must be exactly
\&\fBblocksize\fR bytes long.
.PP
.Vb 1
\& my $plaintext = $c\->decrypt($ciphertext);
.Ve
.SS keysize
.IX Subsection "keysize"
Just an alias for \fBmax_keysize\fR (needed for Crypt::CBC compatibility).
.SS max_keysize
.IX Subsection "max_keysize"
Returns the maximum allowed key size in bytes for the given cipher.
.PP
.Vb 5
\& $c\->max_keysize;
\& #or
\& Crypt::Cipher\->max_keysize(\*(AqAES\*(Aq);
\& #or
\& Crypt::Cipher::max_keysize(\*(AqAES\*(Aq);
.Ve
.SS min_keysize
.IX Subsection "min_keysize"
Returns the minimum allowed key size in bytes for the given cipher.
.PP
.Vb 5
\& $c\->min_keysize;
\& #or
\& Crypt::Cipher\->min_keysize(\*(AqAES\*(Aq);
\& #or
\& Crypt::Cipher::min_keysize(\*(AqAES\*(Aq);
.Ve
.SS blocksize
.IX Subsection "blocksize"
Returns the block size in bytes for the given cipher.
.PP
.Vb 5
\& $c\->blocksize;
\& #or
\& Crypt::Cipher\->blocksize(\*(AqAES\*(Aq);
\& #or
\& Crypt::Cipher::blocksize(\*(AqAES\*(Aq);
.Ve
.SS default_rounds
.IX Subsection "default_rounds"
Returns the default number of rounds for the given cipher. Only some ciphers,
such as MULTI2, RC5, and SAFER, let you set the number of rounds via \f(CWnew()\fR.
.PP
.Vb 5
\& $c\->default_rounds;
\& #or
\& Crypt::Cipher\->default_rounds(\*(AqAES\*(Aq);
\& #or
\& Crypt::Cipher::default_rounds(\*(AqAES\*(Aq);
.Ve
.SH "SEE ALSO"
.IX Header "SEE ALSO"
.IP \(bu 4
CryptX
.IP \(bu 4
See subclasses such as Crypt::Cipher::AES, Crypt::Cipher::Blowfish, ...