Categories and Subject Descriptors

We describe a technique to reliably identify individual inte-grated circuits (ICs), based on a prior delay characterization of the IC. We describe a circuit architecture for a key card for which authentication is delay based, rather than based on a digital secret key. We argue that key cards built in this fashion are resistant to many known kinds of attacks. Since the delay of ICs can vary with environmental condi-tions such as temperature, we develop compensation schemes and show experimentally that reliable authentication can be performed in the presence of significant environmental vari-ations. The delay information that is extracted from the IC can also be used to generate keys for use in classical crypto-graphic primitives. Applications that rely on these keys for security would be less vulnerable to physical attack