I created a theoretical compressor which I haven't yet been able to implement which uses the fact that every sequence of bits appears in pi somewhere, so my compressor would just return the digit offset and the length of data. I keep looking for a source for all the digits of pi though, have yet to find it.
I don't think that's completely true yet, it's just incredibly likely. I don't mean you can't build the thing, you just can't quite prove it accepts all input; it could work in practice before it works in theory.
Re: what komon said, if the offset dwarfs the input, perhaps you could find the offset of the offset, so on and so forth, keeping track of the # of indirections (until that number exceeds the input).
P.s. As the author states in issue #2, "the release date of pifs is an important part of understanding what's going on" ;)
https://blort.org/~kgasso/images/how-to-catch-script-kiddies...
Alternatively, you could release a program that comes with an already long sequence of the decimal section of PI and connects regularly to the internet to download more digits (you could even run the computation & API on a google compute / amazon ec2 instance to keep costs low)