How to Verify a Timestamp

Why Verification Matters

The entire value of a blockchain timestamp depends on verifiability. If no one can independently confirm the proof, it’s no better than a regular file date. TimeProof timestamps are designed so that anyone — a judge, a lawyer, a business partner, or you — can verify them at any time without trusting TimeProof.

Three Levels of Verification

Verification can be performed at increasing levels of independence:

Level	Method	Trust Required
Quick	TimeProof verification page	Trust TimeProof’s interface
Standard	Polygonscan lookup	Trust Polygonscan (public explorer)
Full	Manual hash + Merkle proof + on-chain query	Trust only math and the Polygon blockchain

All three levels confirm the same underlying proof. The difference is how much you do yourself versus relying on TimeProof’s tools.

Quick Verification (TimeProof Page)

The fastest way to verify any timestamp:

Navigate to app.timeprooflabs.com/verify
Drag your file onto the upload area (it’s hashed in your browser — not uploaded)
The system computes the SHA-256 hash and checks it against blockchain records
If found, the page displays: timestamp date, transaction hash, block number, and verified status

This takes seconds and requires no account. See Verification Page Guide for the full walkthrough.

Standard Verification (Polygonscan)

For verification that doesn’t depend on TimeProof’s servers:

Step 1: Get the Transaction Hash

Find the transaction hash from your PDF certificate or the TimeProof dashboard. It looks like: 0x7f8a...3b4c (66 characters starting with 0x).

Step 2: Look Up on Polygonscan

Go to polygonscan.com and paste the transaction hash in the search bar. The transaction page shows:

Status: Success (confirmed on-chain)
Block: The block number
Timestamp: The exact time (UTC) the block was mined
From: The wallet that submitted the transaction (TimeProof’s anchor wallet)
To: The TimeProof smart contract address
Input Data: The anchored hash or Merkle root

Step 3: Confirm the Hash

Look at the Input Data field. For single-file timestamps, your file’s SHA-256 hash is embedded in the transaction data. For batch timestamps, the Merkle root is recorded — you’ll need the Merkle proof to connect your file hash to the root.

See Polygonscan Verification for a detailed walkthrough.

Full Verification (Manual)

For maximum independence — no trust in any third-party tool:

Step 1: Compute the File Hash

Use any SHA-256 tool to hash your original file:

Platform	Command
macOS/Linux	`shasum -a 256 yourfile.pdf`
Windows	`certutil -hashfile yourfile.pdf SHA256`
Online	Any SHA-256 calculator (search “SHA-256 online”)
Python	`hashlib.sha256(open('file','rb').read()).hexdigest()`

The output is a 64-character hexadecimal string. This must match the hash in your certificate exactly.

Step 2: Verify the Merkle Proof (Batch Files)

If your file was part of a batch, the certificate contains a Merkle proof — a series of intermediate hashes that connect your file’s hash to the Merkle root anchored on the blockchain.

To verify the proof:

Start with your file’s hash (the leaf)
For each step in the proof path, combine your current hash with the proof hash and compute SHA-256 of the pair
After walking all steps, you should arrive at the Merkle root
Confirm the Merkle root matches the one recorded in the blockchain transaction

This is pure math — no trust in any service required. Any SHA-256 implementation produces the same result.

Step 3: Query the Blockchain Directly

For the highest level of independence, query the Polygon blockchain directly instead of relying on Polygonscan:

Use any Ethereum JSON-RPC provider (Infura, Alchemy, or run your own node)
Call eth_getTransactionByHash with the transaction hash
Verify the transaction data contains the expected Merkle root
Call eth_getBlockByNumber to confirm the block timestamp

This eliminates even Polygonscan as a trust dependency. You’re verifying directly against the blockchain.

Verifying Legal-Grade Packages

LG packages include additional verification steps:

Identity Attestation (JWS)

Retrieve TimeProof’s public key from /.well-known/jwks.json
Use any JWT library to verify the JWS signature
Confirm the sub claim matches the wallet address in the certificate
Check that exp (expiration) is in the future

Package Integrity (CHECKSUMS)

Run sha256sum -c CHECKSUMS.sha256 in the package directory
Confirm all checksums pass — this verifies no file was tampered with after package generation

Verification Checklist

For any timestamp verification, confirm all of the following:

File SHA-256 hash matches the certificate
Transaction exists on Polygonscan with “Success” status
Block timestamp matches the certificate’s timestamp
Contract address matches TimeProof’s published contract
Merkle proof walks correctly (for batch files)
Identity attestation verifies (for LG packages)

If all items check out, the proof is valid. The file existed at the recorded time, and no one has tampered with the record.

Verification Page Guide — using the online tool
Polygonscan Verification — blockchain explorer walkthrough
Third-Party Verification — for lawyers and auditors
Certificate Guide — understanding certificate fields