Communicate between PHP openssl_encrypt (decrypt) and MQL4 CryptEncode (decode)

I would like to create a proof of concept that results in handshaking code between PHP (on a web site) and a demo MQL4 EA.

This project will demonstrate functionality to encrypt strings in MQL4 and decrypt them in PHP, and in turn to encrypt in PHP and decrypt the string in MQL4 demo EA. 

For this purpose I am not concerned about high levels of security. I don't care what size key we are using. This exercise will be more for the purpose of "obfuscation" and simply making it difficult to snoop in on the communications.

At this time, I am not asking for this project to include integration with my current system.

Outcome: 

1) MQL4 proof of concept EA that can use an input string encrypted by a PHP routine and a key/secret phrase and successfully decrypt the string to the original plain ascii message.  This EA will receive the information in its "extern" variables.  The decrypted ascii message will then be written to a text file.

2) The same MQL4 EA that can use a plain text ascii message and a key, encrypt it and save the outcome to a text file on disk.  

3) A dropdown list in the MQL4 EA will designate whether the action is encrypt or decrypt when the EA is run. 

3) A PHP program running in a website of my designation that will read an ecnrypted string from the URL line, decrypt it using a stored key/secret phrase, and show the result on an HTML page

4) The same PHP program running in a website that will read a clear-string text from the URL line, encrypt it using a stored key/secret phrase, and show the result on an HTML page

5) I am willing for the openssl_encrypt / CryptEncode to use aes128, aes256, or des encryption.  My only concern is the outcome logic that allows the above successful handshaking between the two agents (MQL4/PHP)

6) Delivery of source code at the completion of the project.