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Hash value (digest)

Definition

A fixed-length output produced by a cryptographic algorithm such as SHA-256 applied to a data set. Any change to the input data, however small, produces a different digest. Used to verify that a forensic copy is identical to the original.

Related terms

ACPO principles
Four principles for digital evidence handling published by the UK's Association of Chief Police Officers (now maintained by the Forensic Science Regulator):...
Chain of custody log
The continuous record documenting every person who accessed a digital exhibit, every transfer of possession, every examination action, and the hash values...
Forensic image
A bit-for-bit verified copy of a storage medium, created using a write-blocker to prevent modification of the original. The copy is verified...
Working copy
A copy of an exhibit on which examination work is performed, created from a verified forensic image. The original or master copy...
Write blocker
A hardware or software device interposed between a digital storage medium and the forensic workstation that prevents any write commands from reaching...

Explained in

  • Chain of Custody for Digital MediaA fixed-length output produced by a cryptographic algorithm such as SHA-256 applied to a data set. Any change to the input data, however small, produces a diff...

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