Image::ExifTool::AES(3) User Contributed Perl Documentation
NAME
Image::ExifTool::AES - AES encryption with cipher-block chaining
SYNOPSIS
use Image::ExifTool::AES qw(Crypt);
$err = Crypt(\$plaintext, $key, 1); # encryption
$err = Crypt(\$ciphertext, $key); # decryption
DESCRIPTION
This module contains an implementation of the AES encryption/decryption
algorithms with cipher-block chaining (CBC) and RFC 2898 PKCS #5
padding. This is the AESV2 and AESV3 encryption mode used in PDF
documents.
EXPORTS
Exports nothing by default, but "Crypt" may be exported.
METHODS
Crypt
Implement AES encryption/decryption with cipher-block chaining.
Inputs:
0) Scalar reference for data to encrypt/decrypt.
1) Encryption key string (must have length 16, 24 or 32).
2) [optional] Encrypt flag (false to decrypt).
3) [optional] Flag to avoid removing padding after decrypting, or
to avoid adding 16 bytes of padding before encrypting when data
length is already a multiple of 16 bytes.
Returns:
On success, the return value is undefined and the data is encrypted
or decrypted as specified. Otherwise returns an error string and
the data is left in an indeterminate state.
Notes:
The length of the encryption key dictates the AES mode, with
lengths of 16, 24 and 32 bytes resulting in AES-128, AES-192 and
AES-256.
When encrypting, the input data may be any length and will be
padded to an even 16-byte block size using the specified padding
technique. If the encrypt flag has length 16, it is used as the
initialization vector for the cipher-block chaining, otherwise a
random IV is generated. Upon successful return the data will be
encrypted, with the first 16 bytes of the data being the CBC IV.
When decrypting, the input data begins with the 16-byte CBC
initialization vector.
BUGS
This code is blindingly slow. But in truth, slowing down processing is
the main purpose of encryption, so this really can't be considered a
bug.
AUTHOR
Copyright 2003-2024, Phil Harvey (philharvey66 at gmail.com)
This library is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
REFERENCES
<http://www.hoozi.com/Articles/AESEncryption.htm>
<http://www.csrc.nist.gov/publications/fips/fips197/fips-197.pdf>
<http://www.faqs.org/rfcs/rfc3602.html>
SEE ALSO
Image::ExifTool(3)
perl v5.34.3 2024-01-02 Image::ExifTool::AES(3)
image-exiftool 12.870.0 - Generated Thu Aug 15 08:43:59 CDT 2024