  In this paper, we introduce a novel Communication and Obfuscation Management
Architecture (COMA) to handle the storage of the obfuscation key and to secure
the communication to/from untrusted yet obfuscated circuits. COMA addresses
three challenges related to the obfuscated circuits: First, it removes the need
for the storage of the obfuscation unlock key at the untrusted chip. Second, it
implements a mechanism by which the key sent for unlocking an obfuscated
circuit changes after each activation (even for the same device), transforming
the key into a dynamically changing license. Third, it protects the
communication to/from the COMA protected device and additionally introduces two
novel mechanisms for the exchange of data to/from COMA protected architectures:
(1) a highly secure but slow double encryption, which is used for exchange of
key and sensitive data (2) a high-performance and low-energy yet leaky
encryption, secured by means of frequent key renewal. We demonstrate that
compared to state-of-the-art key management architectures, COMA reduces the
area overhead by 14%, while allowing additional features including unique chip
authentication, enabling activation as a service (for IoT devices), reducing
the side channel threats on key management architecture, and providing two new
means of secure communication to/from an untrusted chip.
