What do you think it's the best method to secure a string in PHP? I speak of hiding its content and avoid malicious changes by the user, but be able to recover the information.
We can use the open_ssl functions, but I prefer using a simpler solution, more platform-compatible, quicker, and without the need of public/private keys.
For example, it can be useful for creating a custom URL that will be accessed with other device, like a QR code shown on a webpage that has to be scanned with iOS's Passbook or similar apps.
I think that this can be accomplished using some obfuscation method (like char replacement using a dictionary), and a trailing hash to ensure the data integrity, but I would like to hear your opinions.