US Patent 9755831 Key extraction during secure boot

One feature pertains to a method for extracting a secret key during a secure boot flow of an integrated circuit. Specifically, the secure boot flow includes powering ON a first volatile memory circuit to generate a plurality of initial logical state values, deriving secret data based on the plurality of initial logical state values, storing the secret data in a secure volatile memory circuit that is secured by a secure execution environment (SEE), clearing the plurality of initial logical state values in the first volatile memory circuit, executing a cryptographic algorithm at the SEE to extract a secret key based on the secret data, and storing the secret key in the secure volatile memory circuit. The secure boot flow controls access to the first volatile memory circuit to secure the secret data and the plurality of initial logical state values from the insecure applications.