PHP AES File Encryption

PHP implementation of the open source aes crypt file format

File specification is described here https://www.aescrypt.com/aes_file_format.html

##Introduction There are many PHP AES implementations available online which offer AES encryption for data streams. It is possible to utilise these low level libraries to encrypt files, but unless you do everything correctly you can end up with an insecure (or broken) library. This library works at a higher level, depending on a low level AES encryption engine (which you can configure), and implementing the open source aes crypt file format.

##Problems There are many problems to solve when implementing file encryption using a low level library such as mycrpt. Many people incorrectly think you can just encrypt data and shove it in a file. Alas, it is not that simple.

The open source file format handles many issues such as null bytes trimming, file integrity and fast password checking. It even comes with file extension identifiers which allows arbitrary data to be tagged within the AES file (unencrypted).

This library makes it easier for users who are only interested in encrypting and decrypting .aes files with passwords. Other technicalities such as file structure, versions & encryption keys are transparent to the user.

##Requirements

1. PHP 5
2. An AES 256 bit Encryption Implementation (you can use the included mcrypt implementation or some other) If you don't have mcrypt available, you only need to implement the AES256Implementation interface using whatever library you want.

##Usage (see example_usage.php)

1. Include the AESCryptFileLib.php class
2. Construct an instance of the library using an AES256 implementation
3. Call the public functions

##Compatibility This library writes version 2 of the file specification defined at https://www.aescrypt.com/aes_file_format.html Backwards compatibility with the older two versions (reading old .aes files) is untested. Output .aes files are fully compatible with any software using the AES Crypt standard file format.

##To do

1. Test reading files stored in version 0 and 1 formats.

##License I believe that open source software should be free for everyone and non restrictive. My code is based on a completely free to use open source file format which I did not invent. I will choose MIT since it seems to be the least restrictive license out there.