Self-Sovereign Identity for the Financial Sector: A Case Study of PayString Service

PayString is an initiative to make payment identifiers global and human-readable, facilitating the exchange of payment information. However, the reference implementation lacks privacy and security features, making it possible for anyone to access the payment information as long as the PayString identifier is known. In this paper, we propose an innovative solution for this issue by integrating a privacy layer based on Self-Sovereign Identity (SSI), Decentralized Identifier (DID) and Verifiable Credential (VC) to the PayString protocol. We also present the first performance evaluation of PayString. Via a large-scale testbed, our experimental results show an overhead which, given the privacy and security advantages offered, is acceptable in practice, thus making the proposed solution feasible.