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Image::ExifTool::AES(3User Contributed Perl DocumentatiImage::ExifTool::AES(3)

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 2003-2013, Phil Harvey (phil at owl.phy.queensu.ca)

       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(3pm)

perl v5.18.1			  2013-01-01	       Image::ExifTool::AES(3)
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