Hard-copy documents can be fraudulently altered after signature too. The question is, how much more burden do you want to impose on the parties to address the infinitesimal fraction of cases where that kind of fraud might be involved.

EDIT: Each party presumably will have email records with the PDF attachment — and if the attachments don't agree, then the parties' lawyers will be busy. But again, how likely is that to happen, and how much time and money do you want to spend to prevent it? At some point you hit diminishing returns (and OCD behavior).

This reminded me of a great talk (in German) by David Kriesel about scanners not scanning correctly but replacing letters and numbers because of pattern matching (if I remember correctly).

It was a really great talk. Not sure if there is an English version somewhere:

https://www.youtube.com/watch?v=7FeqF1-Z1g0

> Not sure if there is an English version somewhere: https://www.youtube.com/watch?v=7FeqF1-Z1g0

Seems to be: https://media.ccc.de/v/31c3_-_6558_-_de_-_saal_g_-_201412282...

Direct: https://cdn.media.ccc.de/congress/2014/h264-hd/31c3-6558-de-...

Which has german/english dual audio, but defaults to german (so presumably google ruined the english track on upload). If your video player doesn't support picking audio, you can probably fiddle with ffmpeg to strip out the german track.