Joel C. Maslak


Crypt::EAMessage - Simple-to-use Abstraction of Encrypted Authenticated Messages


version 1.002


  use Crypt::EAMessage;

  my $eamsg = Crypt::EAMessage->new( hex_key => $hex );

  $encrypted = $eamsg->encrypt_auth($input);
  $enc_ascii = $eamsg->encrypt_auth_ascii($input);

  $decrypted = $eamsg->decrypt_auth($encrypted);


This module provides an easy-to-use method to create encrypted and authenticated messages from arbitrary Perl objects (anything compatible with Storable).

While there are many modules that encrypt text, there are many less that provide encryption and authentication without a complex interface. This module uses AES encryption in CCM mode. This allows two parties to communicate securely, provided they both use the same secret key. In addition to providing privacy, this module also ensures that the message was created by someone who had knowledge of the private key - in otherwords the message was also not tampered with in-transit.

When encrypting, this module produces a message that contains the message's nonce (a unique value that changes the results of the encryption so two identical messages will be encrypted differently), the authentication tag (used to authenticate the message), and the cipher text. It can be formatted in either a "printable" base 64 encoding or in raw binary form.



This is the key used for encryption/decryption (a string of 16, 24, or 32 bytes). Note that the size of the key determines the strength of the AES encryption - a 16 byte string uses AES-128, 24 uses AES-192, 32 uses AES-256.


This is the hex version of the key. This should consist of a string of 32, 48, or 64 hex digits (creating a 16, 24, or 32 byte key).



  my $eamsg = Crypt::EAMessage->new( raw_key => $key );


  my $eamsg = Crypt::EAMessage->new( hex_key => $hex );

Create a new workunit class. It takes either a raw_key or a hex_key parameter. See the raw_key and hex_key attributes.


  my $ciphertext = $ea->encrypt_auth( $plaintext );

Encrypts the plain text (or any other Perl object that Storable can freeze and thaw) passed as a parameter, generating a binary (non-printable) cipher text output.


  my $ciphertext = $ea->encrypt_auth_ascii( $plaintext );

Encrypts the plain text (or any other Perl object that Storable can freeze and thaw) passed as a parameter, generating an ASCII (base64) cipher text output.


  my $plaintext = $ea->decrypt_auth( $ciphertext );

Decrypts the cipher text into the object that was frozen during encryption.

If the authentication or decryption fails, an exception is thrown. Otherwise it returns the plaintext/object.


To generate a key, a simple Perl program can accomplish this - note that you should NOT use standard rand() to do this.

  use feature 'say';
  use Bytes::Random::Secure qw(random_bytes_hex);

  my $hexkey = random_bytes_hex(32);
  say "Key is: $hexkey";

Alternative, you can do this with a one-liner to return a hex key:

  perl -MBytes::Random::Secure=random_bytes_hex -E 'say random_bytes_hex(32)'


Note that this module use Storable. Thus this module should only be used when the endpoint is trusted. This module will ensure that the stored object is received without tampering by an intermediary (and is secure even when an untrusted third party can modify the encrypted message in transit), because thaw is not called unless the message passes authentication checks. But if an endpoint can create a malicious message using a valid key, it is possible that this message could exploit some vulnerability in the Storable module.

This module does not protect against replay attacks.

This module is not protected against timing attacks.


This module implements a tiny subset of the functionality in Crypt::Util which may be a better choice for more complex use cases.


None known, however it is certainly possible that I am less than perfect! If you find any bug you believe has security implications, I would greatly appreciate being notified via email sent to prior to public disclosure. In the event of such notification, I will attempt to work with you to develop a plan for fixing the bug.


Joel Maslak <>


This software is copyright (c) 2016 by Joel Maslak.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.