secShield: Encrypt parameters passed between pages

This class can be used to protect the parameters passed between pages by using encryption.

It takes a string with a list of parameters like the query parameters of an URL.

The class returns a string with the parameters encrypted with a secret key that should be used as a single parameter in a link URL.

The linked page can use the class to decrypt and verify the integrity of the parameters.

If the encrypted parameters are not valid in 10 successive requests, the class may ban the access of users of the same IP address for 1 day.

If the decrypted parameters are valid, the class returns the original parameters in an array.