Forthcoming Presentation at the GlobalPlatform TEE Conference

I’m happy to announce that I’ll be making a presentation at the forthcoming GlobalPlatform 2014 TEE Conference (September 29-30, Santa Clara, CA). Here are the title and abstract:

Virtual Tamper Resistance for a TEE

Derived credentials are cryptographic credentials carried in a mobile device that are derived from credentials carried in a smartcard. The term was coined by the US National Institute of Standards and Technology (NIST) in connection with US Federal employee credentials, but the concept is generally applicable to use cases encompassing high-security enterprise IDs, payment cards, national identity cards, driver licenses, etc.

The Trusted User Interface feature of a TEE can protect the passcode that activates derived credentials from being phished or intercepted by malware, the user being instructed to only enter the passcode when a Security Indicator shows that the touchscreen is controlled by the Secure OS of the TEE. Besides protecting the passcode, it is also necessary to protect the derived credentials themselves from an adversary who physically captures the device. This requires resistance against tampering. Physical tamper resistance can be provided by a Secure Element accessed from the TEE through the TEE Secure Element API, thus combining protection of the passcode against malware with protection of the credentials against physical capture.

Derived credentials can also be protected against physical capture using cloud-based virtual tamper resistance, which is achieved by encrypting them with a key stored in a secure back-end. The device uses a separate credential derived in part from the activation passcode to authenticate to the back-end and retrieve the encryption key. A novel technique makes it possible to do so without exposing the passcode to an offline guessing attack, so that a short numeric passcode is sufficient to provide strong security.

Physical tamper resistance and virtual tamper resistance have overlapping but distinct security postures, and can be combined, if desired, to maximize security.

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