Hash Value Verification
Definition
A mathematical technique used to confirm that a digital file has not been altered. A cryptographic hash (typically SHA-256 or MD5) is computed at the point of acquisition and again at trial; matching hashes demonstrate that the file is identical to the original. Used in courts across multiple jurisdictions to satisfy authentication requirements.
- Purpose
- Confirm a digital file has not been altered
- Common algorithms
- SHA-256, MD5
- Process
- Hash computed at acquisition and again at trial
- Legal use
- Satisfies authentication requirements across jurisdictions
Common questions
What happens in court if the two hash values do not match?+
A mismatch is treated as evidence the file was altered, corrupted, or is not the same file as originally acquired, and it typically triggers a challenge to admissibility unless the discrepancy can be explained and documented.
Why is hash verification usually paired with chain of custody records rather than used alone?+
A hash proves the file's content is unchanged since a given point, but not who had access to it or how it was handled, so custody documentation and hash verification together address integrity and provenance separately.
Is hash value verification specific to any one type of digital evidence?+
No, the same technique applies to disk images, individual files, video recordings, or any digital object, since it operates purely on the underlying byte content regardless of file type.
Related terms
- Anvar P.V. V. P.K. Basheer (2014)
- Indian Supreme Court decision holding that electronic records are secondary evidence and can only be admitted with a Section 65B certificate. Overruled...
- Arjun Panditrao Khotkar (2020)
- Indian Supreme Court decision confirming that the certificate is a condition precedent to admissibility. A court cannot waive the requirement but can...
- Federal Rule of Evidence 901
- The US authentication rule requiring that evidence be supported by proof sufficient to show it is what the proponent claims. Applied to...
- Rebuttable Presumption of Computer Reliability
- The English and Welsh approach following the repeal of Section 69 PACE: courts presume computers function correctly unless the party challenging the...
- Section 65B Certificate (Indian Evidence Act / BSA 2023)
- A signed statement by a responsible official certifying that an electronic record was produced by a computer in regular use during the...