When setting up the Singpass app on your device, you will be issued a digital identity by the National Certification Authority (NCA). This is used as proof of your online identity whenever you use your Singpass to transact with digital services.

Your digital identity is represented by the authentication certificate issued to you. It comes with a unique serial number that can be seen in your Singpass app settings, under "Digital identity details".

These certificates are used as part of Public Key Infrastructure technology, and can be used as a trusted means of authenticating a person’s identity for the purposes of electronic transactions. When you scan the QR code to log in with Singpass, the authentication certificate is checked in order to verify your identity.

The authentication certificate is valid for 1 year in the Singpass app. Once it expires, you will be prompted to renew the authentication certificate. You can proceed to renew the certificate, in order to continue using your Singpass to transact with digital services.

The authentication certificate is different from your signing certificate, which will be used when you interact with the Sign and Authorise services.