Concerns about hardware security have increased with the wide availability of sophisticated tools and invasive techniques to discover the secrets and keys that traditionally protect devices from counterfeiting, tampering and theft-of-service. With both revenues and reputation at stake, a new approach to hardware security that does not depend on a stored key is necessary. Hardware intrinsic security (HIS), based on inherent, device-unique properties, provides secret key storage without storing a key. Using physically unclonable functions (PUFs), HIS systems exploit intrinsic deep-submicron process variations to authenticate, configure and/or monitor the production of electronic devices. An independent lab, SiVenture, performed several experiments, including voltage contrast attacks using a scanning electronic microscope (SEM) and a focused ion beam (FIB), designed to discover the secret key in an SRAM PUF used in an HIS system from Intrinsic-ID. These experiments confirmed that invasive attacks fail against the HIS approach, where no key is stored within the device.