A Modular Open-Source Cryptographic Co-Processor for Internet of Things.

The security of computer systems can be increased effectively by using cryptographic co-processors to encapsulate secrets and speed-up the computationally intensive cryptographic functions. This can be especially advantageous for Internet of Things devices, as they usually have to be very efficient in cost, space and timing. However, these devices are also at greater risk of becoming targets of hardware attacks, as they handle sensitive data and are physically exposed to a nearly unrestricted population of users. This paper describes a modular cryptographic co-processor, allowing it to be applied in different scenarios and easily adjusted to concrete system specifications. The co-processor design is also open-source and freely available for anyone to further applications and modifications. It implements the basic cryptographic functions of symmetric encryption, hashing and a pseudo random number generation, with an interface to a true random number generator. In addition, the co-processor offers additional interfaces for key generation. A specific realization is presented in detail, compared to existing solutions, and its resilience against various attacks is discussed.