Key Attestation from Trusted Execution Environments

Credential platforms implemented on top of Trusted Execution Environments' (TrEEs) allow users to store and use their credentials, e g, cryptographic keys or user passwords, securely One important requirement. for a TrEE-based credential platform is the ability to (West that a credential has been created and is kept within the TrEE Credential properties, such as usage permissions, should be also attested Existing attestation mechanisms are limited to attesting which applications outside the TrEE are authorized to use the credential In this paper we describe a novel key attestation mechanism that allows attestation of both TrEE internal and external key usage permissions We have implemented this attestation mechanism for mobile phones with M-Shield TrEE.