I wanted to understand the problem at an abstract level, rather than describing my exact use case, leading people into digressions, debates, etc. Also note, I

I wanted to understand the problem at an abstract level, rather than describing my exact use case, leading people into digressions, debates, etc. Also note, I answered my own question with HMAC being the probable solution (before anyone else mentioned HMAC), and others seemed to verify that this might be the best fit by answering with the same thing shortly thereafter. If I can give permission and I only need to provide permission, the only thing I only need is a way to transmit a message and prove that it wasn't modified while in-transit.