Signed PDF certificate
Affidavit listing the file name, hash, and timestamp. Verifiable on this site.
How to · File, document, image
How to certify a file, document, or image as legal evidence
To certify a file as legal evidence, upload it and let the platform compute a SHA-256 hash, request a qualified RFC 3161 timestamp, and sign the manifest with Ed25519. The signed PDF references the original — any later modification breaks the hash and is detectable.
SHA-256File hash
Ed25519Signed manifest
RFC 3161Qualified timestamp
Why a plain copy of a file is not enough.
File metadata is trivially editable. Without an independent proof chain, the "when" of a file is your word.
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Created/modified dates are editableAny file system tool can backdate a file.
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EXIF data in photos is editable tooFree tools rewrite GPS, date, and device metadata.
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Multiple copies, no integrity guaranteeWithout a hash, you cannot tell which copy is the original.
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Courts question undated digital documentsA certified timestamp answers the "when" beyond dispute.
What a certified file capture includes.
SHA-256 hash file
Hex digest of the original. Re-hashing the file later proves no modification.
RFC 3161 timestamp
Qualified independent signature binding the hash to a specific moment in time.
Ed25519 signature
The platform's signature on the manifest containing the hash and timestamp.
Metadata ZIP
Manifest, signature, public key, hashes, and timestamp request/response.
Verification URL
Public verification endpoint. Anyone can re-verify the chain without an account.
How to certify a file in four steps.
1
Go to /certificates/newSelect File certificate.
2
Upload the filePDF, image, video, document — any file up to 100 MB.
3
Wait for the hash, timestamp, and signatureSHA-256 hashing, RFC 3161 timestamp request, Ed25519 signing — all automatic.
4
Download the certificate packageKeep the original file and the certificate together. Re-verification needs both.
Common use cases for certified file evidence.
IP infringement →Lock the SHA-256 of your original work to a date earlier than any infringement.
Insurance claims →Certify damage photos before repairs begin.
Email evidence →Upload a .eml source file to preserve the full headers.
Workplace evidence →Certify saved emails, exported chat logs, and HR documents.
File-certification questions.
How do I prove a document was not altered after a certain date?
Upload the document as a File certificate at /certificates/new. The platform computes a SHA-256 hash of the file and binds it to a qualified RFC 3161 timestamp. Any later modification to the file changes its hash — proving alteration.
How do I certify a PDF contract as legal evidence?
Go to /certificates/new, select File, and upload the PDF. The certificate hashes the file, requests a qualified timestamp, and produces a signed PDF certificate referencing the original. Store both files; either can be verified independently.
How do I create a legally certified version of an image or photo?
Upload the image as a File certificate. The SHA-256 hash and qualified timestamp prove the image existed in this exact form at the moment of certification. This is the standard approach for insurance, IP, and damage-evidence claims.
What is a document timestamp and how is it used in legal disputes?
A qualified document timestamp is a signed assertion by an RFC 3161 timestamp authority that a specific cryptographic hash existed at a specific moment. Courts treat qualified timestamps as strong evidence of when a file existed in its current form.
Is this legal advice?
No. This service creates technical evidence artifacts. Legal admissibility depends on jurisdiction and circumstances. Consult qualified legal counsel for advice specific to your situation.
Ready to certify?
Upload your file. The hash, signature, and timestamp lock its current form to this moment in time.