A particular method includes generating, at a secure user plane location (SUPL) server, a message to be sent to a mobile device, the message including: a server certificate including an identifier of the SUPL server and a public key of the SUPL server; and a request for a device certificate of the mobile device. The method also includes receiving a reply from the mobile device that includes a device certificate of the mobile device; and authenticating the mobile device as associated with a SUPL user based on the device certificate.