Blockchain Timestamping

Blockchain Timestamping

(Available only in Enterprise Edition)

You can enable blockchain-based timestamping for documents that are digitally signed using Zoho Sign.

What is a blockchain?

A blockchain is a constantly growing list of records (called blocks) that are virtually chained or linked using cryptography. Each block contains a cryptographic hash of the previous block, a timestamp, and data corresponding to a transaction. Blockchains are primarily used as a permanent, open digital ledger that records online transactions. Records in a blockchain cannot be altered retroactively without leading to a change in all the subsequent blocks. 

A public blockchain is decentralized, meaning it stores its data on a distributed, peer-to-peer network, and not on any one particular device or server. This shields the blockchain from being attacked or exploited by hackers, as there's no centralized control system to target. A public blockchain is also entirely open, with no access restrictions. This enables anybody to access it, and add and validate transactions.

Why use blockchain timestamping?

Blockchain-based timestamping allows Zoho Sign to offer an additional measure of document verification, and publicly establish signer accountability. The blockchain captures the document signing event in the form of a public entry, which is accessible to all and immune to change. Since the blockchain is, by design, resistant to tampering, this feature creates an immutable record of document integrity and non-repudiation.

How does blockchain timestamping work in Zoho Sign?

Whenever a document is signed digitally using Zoho Sign, an Ethereum transaction takes place in the background, to which the hash of the signed document is added in the transaction notes. This transaction information is then appended in the form of a block to the Ethereum public blockchain, carrying a timestamp that affirms the signing of the document at that time. Anyone can access the blockchain at any time, to verify that the document was signed at the given time, or that the signed document did exist in that instant.

Will my document be exposed to the public with blockchain timestamping?

No, it will not. Only the hash of the signed document is added to the public blockchain, not the document itself. A hash is a unique, unintelligible, alphanumeric value generated by performing an algorithmic action on a string or a collection of strings in a document. Hashing is a strictly one way, irreversible process. The signed and unsigned versions of the same document will generate different hash values. Adding the signed document's hash to the blockchain does not expose the document data or its contents to those accessing the blockchain. It simply allows them to note down the hash value for verification of document authenticity. 

Enabling blockchain timestamping

To enable blockchain timestamping:

  1. Hover over Settings in the left navigation panel on your Zoho Sign dashboard.
  2. Select Account settings under Admin from the dropdown menu.
  3. Toggle the 'Add documents to blockchain' option at the bottom of the page to ON.

Verifying document authenticity on the blockchain

Upon the successful completion of document signing, the status of the associated blockchain transaction can be seen on the Detailed Document View page of the respective document.

The transaction may take a few minutes to execute, depending on the length of the transaction queue at the time. During this period, the status of the transaction will show as 'PENDING' in the document page.

Click View more to open a hover-box that lists the details associated with the signed document such as sign completion time, transaction block commit time, transaction ID, and the document hash (SHA-256). 

For a transaction that is 'PENDING', the transaction ID and transaction block commit time will not be present.

Upon the execution of the Ethereum transaction, the transaction block will have been added to the blockchain, and the status of the transaction changes to 'SUCCESS' in the document page.

The transaction ID and transaction commit time will now be listed in the hover-box opened by clicking View more.

Clicking on the link icon in the hover-box will take you to the BlockExplorer website (etherscan.io) for the Ethereum public blockchain where you can verify the transaction and the signing of the document.

To verify the document authenticity on the blockchain:

  1. Note down the document hash from the hover-box opened by clicking View more on the document page inside Zoho Sign. 
  2. On the transaction page in the BlockExplorer website, click Click to see more to view the Input Data field. This field lists the hash values of the documents that were a part of the transaction data, each separated by '0000'.
  3. Compare the values with the document hash noted down from the document page on Zoho Sign. If the noted document hash is present as one of the values, the signing of the document is verified to have taken place at the recorded time.

  4. Additionally, you can generate the hash (SHA-256) for the signed document copy yourself using any SHA-256 hashing tool, and compare it with the hash value listed on the transaction page in the BlockExplorer website to verify the signing of the document at the recorded time. The document hash can also be generated from the terminal of your operating system for the signed document using the following commands.

    • OpenSSL: openssl dgst -sha256 <filename>
    • Windows: CertUtil -hashfile <filepath> SHA256
    • MacOS: shasum -a 256 <filepath>
    • Linux: sha256sum <filepath>

Note:

  • Upon the successful execution of the blockchain transaction, details such as sign completion time, transaction block commit time, and transaction ID will be added to the document completion certificate. These details will not be present in the completion certificate if the transaction is still pending execution.
     
  • Presently in BETA and available at no additional cost. May be subject to additional pricing upon full release.

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