Motivation: Online document signing has become an increasingly important and popular option. Existing signing platforms do not protect users’ document confidentiality well, and the signing process highly relies on the user’s trust in these platforms. To this end, we aim to leverage the blockchain and decentralized identity technologies to develop a more accountable and secure document signing platform such that users can ensure the document’s traceability and privacy protection without trusting the centralized platform.

Architecture: The platform consists of four main roles. A document owner can create her document case and add a set of signers. The TrustedSign platform controls the signing flow and authenticates the signers based on either two-factor authentication or decentralized identity. The signers who receive the signing notification can sign on the document using an electronic signature or digital signature, depending on the selected authentication method. The owner’s document is securely shared with the signers, ensuring that the TrustedSign platform can never have access to the document’s content. The document creation and signing actions are recorded on the blockchain, which is traceable and accountable.

Key Features: (1) Online document signing with both electronic signature and digital signature. It allows users to check the signing status, and ensures real-time verification based on blockchain for strong traceability and accountability. (2) Flexible signer authentication options. It supports both two-factor authentications based on the email address, phone number, and passcode, as well as decentralized identity based on unique keys stored on the blockchain. (3) Strong document confidentiality. The owner’s document is shared with the signers either offline or using cryptographic techniques (i.e., the keys are held by designated users only). It ensures that the document is highly protected, even against the TrustedSign platform. (4) Smart agreement workflow. It allows users to use their own documents or templates provided by the platform. Also, it supports flexible and configurable workflow such that users can design and automate complex agreement processes to save time.