I'm trying to make a server API in PHP, which will be contacted by VB.NET (WinForms) on the client.
This is what should happen: The client form will contact the API with a string "A". If A exists in the server's connected SQL database, the API will return "A" encrypted with an associated string "B" in the database (result "C"). The client will attempt to decrypt C using a locally provided string (which ought to be B, if all is well).
I can figure out the encryption and decryption in VB.NET using 128-bit ECB AES. However, since I'm new to PHP, I don't want to write an API that isn't compatible with my VB.NET decryption suite. So which encryption and decryption suite/APIs should I use in PHP and VB so as to be cross-platform compatible?