This isn't as new as the author thinks. Doesn't have to be new to be interesting, of course :)
I know this was done at one large tech company around 2010 for an internal announcement email. Different people got copies with slightly different Unicode whitespace, despite the email having ostensibly gone directly to an "all employees" alias.
The fingerprinting was noticed within half an hour or so. (Somebody pasted a sentence to an internal IRC for discussion, and as is the case with Unicode and IRC, it inevitably showed up as being garbled in exciting ways for some people).
I know this was done at one large tech company around 2010 for an internal announcement email. Different people got copies with slightly different Unicode whitespace, despite the email having ostensibly gone directly to an "all employees" alias.
The fingerprinting was noticed within half an hour or so. (Somebody pasted a sentence to an internal IRC for discussion, and as is the case with Unicode and IRC, it inevitably showed up as being garbled in exciting ways for some people).