The legal thing does make reference to the technical thing in Europe[1] (and probably elsewhere too), by making digital signatures (which use crypto) legally bi

The legal thing does make reference to the technical thing in Europe[1] (and probably elsewhere too), by making digital signatures (which use crypto) legally binding. The question is more how courts would rule in a case where a colliding document is signed. That would probably depend on whether you can prove which of the two parties authored the colliding document (since that's a requirement for this particular attack). (Note: I don't know whether this attack is practical for qualified electronic signatures as used by EU countries.) [1]: https://en.wikipedia.org/wiki/Qualified_electronic_signature https://en.wikipedia.org/wiki/Qualified_electronic_signature