To support authentication of a mobile device, an application server obtains an application identifier and password and creates an encrypted value by encrypting a combination of the password and a lime based value. The application server transmits the application identifier and encrypted value over a communication network to the mobile device as a credential, and the mobile device sends the credential over the network to a secure server providing an application assistance service. The secure server independently computes an encrypted value by encrypting the combination of the password and the time-based value. If the encrypted value front the received credential matches the encrypted value computed by the secure server, that server grants access to the assistance service for the mobile device.