PHP Encrypt Files: Encrypt and decrypt data with a given key and salt

This class can encrypt and decrypt data with a given key and salt vector.

It can take a given data string and uses the MCrypt library to encrypt the data using a given key and salt vector.

The class can also do the opposite, i.e. decrypt the previously encrypted data and decrypt it with the given key.

The decrypted data can be returned as a string or served for download.