[fredley]

Very interesting tool, although storing as typos does seem to be a bit visible and prone to mistaken 'correction'. Other approaches to consider might be:

* Changing punctuation for visually identical, but different characters. This would not work for printed documents however.

* Encoding only 'believable' typos, e.g. it's its. You could encode a binary stream across all instances of it(')s, or other substitutions.

* Encoding the stream in whitespace, e.g. Two/One spaces after a full stop. Printed documents would be lossy though (as full stops at line endings would be ambiguous). There are error detection/correction systems that can help though.

[bambax]

Typical OCR errors would be interesting too: confusion between the letter "n" with the letters "ri" for example.

It would be visually challenging to detect (and also, maybe, difficult for an OCR engine).

[nrjames]

Snow is interesting and uses white space instead. http://www.darkside.com.au/snow/

[jwilk]

Discussed on HN:

https://news.ycombinator.com/item?id=17524693

[m4xm4n]

Yeah, I need to work on making the displacements and replacements a bit more context-aware (& probably linguistically aware). There are cases where it can "replace" a character with the same character, for example.

I do like your idea about visually similar but distinct character replacement. That would be a really fun one to implement.