Hash verification
Also known as: Hash-Verifikation, integrity proof, checksum, SHA-256
Mathematical proof that an exhibit is unchanged since acquisition, using a cryptographic hash value recalculated and compared at every step.
A hash value is a unique fingerprint of a data set. If it matches the acquisition value after transport, copying or analysis, integrity is proven; if it differs, the exhibit is no longer usable in that form. The European Union Agency for Law Enforcement Cooperation (incl. EC3) (Europol) report lists "validation with mathematics" as a core element of its definition of digital forensics.