On-board credentials with open provisioning

Securely storing and using credentials is critical for ensuring the security of many modern distributed applications. Existing approaches to address this problem fall short. User memorizable passwords are flexible and cheap, but they suffer from bad usability and low security. On the other hand, dedicated hardware tokens provide high levels of security, but the logistics of manufacturing and provisioning such tokens are expensive, which makes them unattractive for most service providers. A new approach to address the problem has become possible due to the fact that several types of general-purpose secure hardware, like TPM and M-shield, are becoming widely deployed. These platforms enable, to different degrees, a strongly isolated secure environment. In this paper, we describe how we use general-purpose secure hardware to develop an architecture for credentials which we call On-board Credentials (ObCs). ObCs combine the flexibility of virtual credentials with the higher levels of protection due to the use of secure hardware. A distinguishing feature of the ObC architecture is that it is open: it allows anyone to design and deploy new credential algorithms to ObC-capable devices without approval from the device manufacturer or any other third party. The primary contribution of this paper is showing and solving the technical challenges in achieving openness while avoiding additional costs (by making use of already deployed secure hardware) and without compromising security (e.g., ensuring strong isolation). Our proposed architecture is designed with the constraints of existing secure hardware in mind and has been prototyped on several different platforms including mobile devices based on M-Shield secure hardware.