How It Works

High-Level User Flow

nChain Sign offers an intuitive document signature process, where the complexity of blockchain interaction is handled internally by the application.

Product Workflow – Document Signature with nChain Sign

Alice (Requestor) requests Bob (Signer) to sign his new employment contract.

  1. Alice requests Bob to sign his new employment contract.

  2. Alice logs into nChain Sign, uploads the document and defines the workflow settings.

  3. Alice sends the document to Bob. A blockchain transaction is created, providing immutable proof that the signature has been requested.

  4. Bob receives an email notification, prompting him to review the document and sign it.

  5. After signing, a notification is sent to Alice, indicating that Bob has signed the document. A new blockchain transaction is triggered to indicate that the document has been signed.

  6. When required, permissioned verifiers can independently attest to the signature on the blockchain.

Digital Signature Process

To enforce security for signed documents, nChain Sign provides cryptographic signatures, as follows:

  • A digital signature on the document related to the users included in the Signature Request to which the document was attached.

  • A digital signature related to the organisation (as in Web2 solutions).

Custodial vs Non-Custodial Document Digital Signatures

There are two versions of the digital signature bound to a document:


  • The application digitally signs the document using keys internally assigned to the signer. The application re-signs on top of that signature with keys specifically dedicated to this purpose.

  • The application re-signs on top of that signature with keys specifically dedicated to this purpose.


  • The user can choose to sign with their own keys, linked to their digital identity, and using the signature algorithm of their choice. Self-custody of keys allows for full sovereignty of data.

  • The application re-signs on top of that signature with keys specifically dedicated to this purpose.

Note: nChain Sign currently only provides support for the custodial version of digital signatures. Non-custodial functionality is planned for release in 2024 (v2.0).

Blockchain Transactions

Blockchain-based digital signatures provides the following benefits:

  • Immutable record keeping.

  • Storage of data on chain removes the need for third party interaction.

For each signed document, there are two blockchain transactions:

  1. A “Request Signature” transaction that logs the event when a document has been sent for signature.

  2. A “Signed Document” transaction that logs the event when a document has been signed.

For simplicity, the application handles all blockchain interactions (handling of blockchain keys, BSV funding, etc.).

Verifying the Identity of Signers

Magic Link Signing: The most basic level, where access to a specific email or URL is required. The assumption is that if you have access to the unique link sent to a verified email, you are the intended signer.

In future versions (planned for release in 2024), nChain Sign will verify the identity of signers through a multi-tiered approach, offering various levels of security based on the signer's needs:

  • Password Sign-In for Document: A step up in security, this level requires the signer to enter a password to access and sign the document. This password is typically set by the requestor for the document or session and separately communicated to the signers.

  • Password Sign-in Required for Account: This level involves signing in to the user's account with a password before being able to sign the document. It ties the document signature to the account security.

  • Full Digital Identity Verification (once SSI wallet functionality is available): The highest level, which includes full digital identity verification. This can involve methods to ensure the signer's identity is thoroughly verified on a registered mobile device.

Each level will provide additional security measures, ensuring that the identity of the signer is progressively more secure and verifiable.

Note: nChain Sign currently only provides the magic link access. Other tiers are planned for release in 2024 (v2.0).

Verifying a document that has been signed on nChain Sign

Verification is simple and can be done through our platform. By comparing the document's hash on the blockchain with the hash of your original document, you can confirm its authenticity and integrity.

Signing a document with multiple parties

nChain Sign supports multi-party signing. Each party signs the document with their own key, and the blockchain records each signature sequentially, ensuring a clear order of signing.

nChain Sign vs other e-signature platforms

nChain Sign leverages blockchain technology for enhanced security, provides self-sovereign signatures for greater control and privacy, and offers an immutable record of the signing process, setting it apart from traditional e-signature platforms.

Signing a document

This section details what information is recorded on the blockchain and discusses whether others can view my document on the blockchain.

When you sign a document using our platform, only a cryptographic hash of the document is placed on the blockchain. A hash is like a digital fingerprint; it's unique to your document but doesn't reveal any of its contents.

Your private key, which is a secret code only you know, is used to create a digital signature that's unique to you and the document. This signature is what gets attached to the document's hash. The hash and signature combination is then recorded on the blockchain.

This process does two things:

  1. Verifies You as the Signer: The digital signature gives greater certainty that you, and only you, signed the document.

  2. Secures the Document: The hash ensures that the document can't be altered without detection.

To see the actual content of your document on the blockchain, a party would need to have the original document and your permission to compare the hash and verify the signature. Your documents remain private and are only shared with people you choose.

Our platform leverages blockchain to provide maximum security while maintaining your privacy.

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