This disclosure describes techniques for authenticating one or more devices of a user in association with cloud computing services. The techniques include generating credential portions. The credential portions may be used in a signing protocol between one of the user devices and a cloud authenticator. The signing protocol may generate a signature that may be used in authentication with a cloud computing service. Furthermore, the user may be able to use any one of the user devices to log in to an online service after enrolling only a single user device with the online service. As such, the cloud authenticator may assist multiple user devices to authenticate with the cloud computing service.