Prove Your Files Are Exactly As They Were

What evidence integrity means

Evidence integrity is a narrow, precise claim: a file is bit-for-bit identical to a previously recorded state. It does not describe who collected the file or what device it came from — it answers only the question has this changed? That focus is what makes integrity the foundation everything else builds on. Before anyone can argue about where a file came from, they first have to show it has not been touched. Tamper-proof file integrity software gives you a defensible, repeatable way to make that showing.

The hash + RFC-3161 timestamp method

A cryptographic hash is a fixed-length fingerprint computed over a file's contents; record it once and you can re-check it at any time. e-Dex computes several algorithms per file — MD5, SHA-1, SHA-256, SHA-512 and BLAKE3 — so a verifier can match against whichever value was originally stored. To fix the result in time, you can attach an RFC-3161 trusted timestamp from an independent Time-Stamping Authority, which records the exact moment the integrity values were captured. Together, the hash and the timestamp answer both what the file was and when that was true.

Detect any change, however small

Cryptographic hashes have the avalanche effect: flip a single bit of the input and roughly half the output bits change, producing an entirely different value. There is no such thing as a small, quiet edit that slips past — a one-character change to a document, a single altered pixel, or silent disk corruption all yield a hash that no longer matches the recorded one. The verdict is binary and unambiguous: the value either matches or it does not.

From a single file to a full self-verifying evidence pack

The same method scales. Hash one file to confirm a download, or hash an entire folder of working papers, exhibits or extracted data and record an overall result across the set. e-Dex packages the files together with their recorded hashes so a recipient can re-verify the whole batch later, on their own machine, without trusting you or any server. A self-verifying pack means the proof travels with the evidence rather than living in a separate spreadsheet that can drift out of sync.

Certify integrity for the record

When you need a document for the file, e-Dex produces a readable certificate listing each file, its hashes and a clear match or mismatch result. For extra assurance you can apply a PAdES digital signature with a Digital Signature Certificate on a USB token, binding the signer's identity to the document so any later edit is detectable, and attach the RFC-3161 timestamp described above. The result is a signed, dated, independently checkable record of integrity. To see what one looks like, read our explainer on the evidence integrity certificate or on what an integrity seal is, and you can always verify a certificate independently in your browser.

Frequently Asked Questions

What is tamper-proof file integrity software?
It is software that records a cryptographic fingerprint (hash) of your files and lets you re-check that fingerprint later. If even one byte changes, the recomputed hash no longer matches, so any tampering or corruption is detectable. e-Dex does this offline on your own Windows machine and can also produce a signed, timestamped certificate of the result.

Does e-Dex need an internet connection?
No. Hashing files, comparing them against recorded values and generating the integrity certificate all happen locally, so your files never leave your computer. The only step that uses the internet is applying an optional RFC-3161 trusted timestamp from a Time-Stamping Authority.

How does a hash detect even the smallest change to a file?
A cryptographic hash exhibits the avalanche effect: changing a single bit of the input changes roughly half of the output bits, producing a completely different value. Because the new hash will not match the recorded one, any alteration however small shows up as a mismatch.

Is e-Dex really free?
Yes. e-Dex, the Digital Evidence Integrity Suite from Innovativa SoftTech in Pune, is free to download and use on Windows. There is no charge for hashing files, verifying integrity or generating a certificate.