Encryption Class: Encrypt and decrypt data with mcrypt

This class can be used to encrypt and decrypt data with mcrypt extension.

It can encrypt a data block using a given key. The encrypted data is returned encoded with a variant of the base64 encoding algorithm that replaces +, / and = characters by -, _ and empty string.

The class can also do the opposite, i.e. decrypt the data with the same key after decoding the base64 encoded encrypted data.