What is legal status of document digest? Are there special regulations which hash functions are considered in legalise?
Most important: Which digest functions would be reasonable nowadays for securing files against forgery, being altered (and having legally considered proofs, just like digital signatures)?
As we know, before message is signed with asymmetric cryptography, firstly it is digested with hash function.
Therefore, considering digital signature as legal proof/evidence implies that message digest must be considered as legal proof/evidence as well (e.g. 2nd preimage attack = against forgery of document = proving that document has not been altered, etc.).
Question is about hash function creating such document digest, their legal status and attack resistance (especially against 1st & 2nd preimage attacks)