Trust but verify attestation with revocation
Posted by Rob Barnes & Shawn Willden, Android Security & Privacy Team Billions of people rely on their Android-powered devices to securely store their sensitive information. A vital component of the Android security stack is the key attestation system . Android devices since Android 7.0 are able to generate an attestation certificate that attests to the security properties of the device’s hardware and software. OEMs producing devices with Android 8.0 or higher must install a batch attestation key provided by Google on each device at the time of manufacturing. These keys might need to be revoked for a number of reasons including accidental disclosure, mishandling, or suspected extraction by an attacker. When this occurs, the affected keys must be immediately revoked to protect users. The security of any Public-Key Infrastructure system depends on the robustness of the key revocation process. All of the attestation keys issued so far include an extension that embeds a certificate...