Why stop at bytes? Let's split it in individual bits and then look up the bits in pi!

But Pi's binary expansion is not very practical for this purpose, since it's 11.0010...

OTOH. e is 10.1011...

Let's stick to fractional digits (the ones right of the binary point) at index 0 we have 1 and at index 1 we have 0.

So, to encode a stream of bytes so that each bit is encoded as the index of that bit in the e, all you need to do is to xor it with 0xFF