Introduction

Transaction Signing API Specifications

This document outlines the technical specifications for the Singpass Transaction Signing API, designed to enable secure and seamless transaction signing for applications integrating with Singpass. It details the API endpoints, authentication mechanisms, request/response structures, and security protocols to ensure integrity, confidentiality, and user trust.

This specification serves as a guide for developers and system integrators to facilitate smooth implementation and interoperability.

Flow Diagram

Refer to this diagram for an overview of the transaction signing flow and the interactions between RP, Singpass and other dependencies.

RPs are expected to implement the following steps referenced from the flow diagram above:

Step(s)	Component	Summary	Specifications
1	Frontend	Retrieve Singpass transaction signing javascript (Singpass JS)	Embedding Singpass JS
2	Frontend	Initialise a transaction signing session via Singpass JS	Init Transaction Signing
6	Backend	After receiving the sign code, invoke Singpass API to exchange it for the user-signed transaction hash	Exchange Transaction Signature