Re:I don't get it. (Score 2, Insightful)

One-way hashing would do this relatively easily. Similar to passwords if you hash the original content and then the tested content and they match there is a very high probability that it is the same original content. It is also irreversible (in bounded time).

Either way I'm not picking one up, I'll go to hand-crank radio and telegrams before I become a beacon of marketing information.