PHP: Passing encrypted data via URL [closed]

I have a secure message that I need to pass via query string to an external website. This does not have any connection to the same database or anything else. I am trying to encrypt the data, send it via the query string and the decrypt it on the other end. The problem is that it is not decrypting it but if I run it all on the same page the functions do work. The issue seems to be that I am using rawurlencode to make it so I can pass it and then rawurldecode on the other end but it does not produce the same values. The below screenshot is what I send to the rawurlencode. Is there a different way to pass this data to another website via querystring keeping this info? I have also tried urlencode