# Transaction Signing

## 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.

<figure><img src="https://372330916-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FXnljQgt54HuOtH3cKCRP%2Fuploads%2F93qMpp45f3LlS8od3Vd3%2Fimage%20(1).png?alt=media&#x26;token=592dcc3c-6e20-41de-9cb3-0534703fd75c" alt=""><figcaption></figcaption></figure>

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

<table><thead><tr><th width="105">Step(s)</th><th width="140">Component</th><th>Summary</th><th width="247">Specifications</th></tr></thead><tbody><tr><td>1</td><td>Frontend</td><td>Retrieve Singpass transaction signing javascript (Singpass JS)</td><td><a href="transaction-signing/embedding-singpass-js">Embedding Singpass JS</a></td></tr><tr><td>2</td><td>Frontend</td><td>Initialise a transaction signing session via Singpass JS</td><td><a href="transaction-signing/init-transaction-signing">Init Transaction Signing</a></td></tr><tr><td>6</td><td>Backend</td><td>After receiving the sign code, invoke Singpass API to exchange it for the user-signed transaction hash</td><td><a href="transaction-signing/exchange-transaction-signature">Exchange Transaction Signature</a></td></tr></tbody></table>