Like, could you just invert all the bits in a block of data and turn it into nonsense?

Or shift/rotate bits, so 10000101 would become 00001011, rather than using an encryption function.

It would be easy to break if you just figured out which bit operations were made, but it’s a wierd thing to do so… would it be obvious at all that it was such a simple encryption method from the raw data?

Just had that thought, it sounds like a ‘security through obscurity’ measure.