1Image::ExifTool::AES(3)User Contributed Perl DocumentatioInmage::ExifTool::AES(3)
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6 Image::ExifTool::AES - AES encryption with cipher-block chaining
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9 use Image::ExifTool::AES qw(Crypt);
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11 $err = Crypt(\$plaintext, $key, 1); # encryption
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13 $err = Crypt(\$ciphertext, $key); # decryption
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16 This module contains an implementation of the AES encryption/decryption
17 algorithms with cipher-block chaining (CBC) and RFC 2898 PKCS #5
18 padding. This is the AESV2 and AESV3 encryption mode used in PDF
19 documents.
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22 Exports nothing by default, but "Crypt" may be exported.
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25 Crypt
26 Implement AES encryption/decryption with cipher-block chaining.
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28 Inputs:
29 0) Scalar reference for data to encrypt/decrypt.
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31 1) Encryption key string (must have length 16, 24 or 32).
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33 2) [optional] Encrypt flag (false to decrypt).
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35 3) [optional] Flag to avoid removing padding after decrypting, or
36 to avoid adding 16 bytes of padding before encrypting when data
37 length is already a multiple of 16 bytes.
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39 Returns:
40 On success, the return value is undefined and the data is encrypted
41 or decrypted as specified. Otherwise returns an error string and
42 the data is left in an indeterminate state.
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44 Notes:
45 The length of the encryption key dictates the AES mode, with
46 lengths of 16, 24 and 32 bytes resulting in AES-128, AES-192 and
47 AES-256.
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49 When encrypting, the input data may be any length and will be
50 padded to an even 16-byte block size using the specified padding
51 technique. If the encrypt flag has length 16, it is used as the
52 initialization vector for the cipher-block chaining, otherwise a
53 random IV is generated. Upon successful return the data will be
54 encrypted, with the first 16 bytes of the data being the CBC IV.
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56 When decrypting, the input data begins with the 16-byte CBC
57 initialization vector.
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60 This code is blindingly slow. But in truth, slowing down processing is
61 the main purpose of encryption, so this really can't be considered a
62 bug.
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65 Copyright 2003-2021, Phil Harvey (philharvey66 at gmail.com)
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67 This library is free software; you can redistribute it and/or modify it
68 under the same terms as Perl itself.
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71 <http://www.hoozi.com/Articles/AESEncryption.htm>
72 <http://www.csrc.nist.gov/publications/fips/fips197/fips-197.pdf>
73 <http://www.faqs.org/rfcs/rfc3602.html>
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76 Image::ExifTool(3pm)
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80perl v5.32.1 2021-04-26 Image::ExifTool::AES(3)