RECO-LFSR: Reconfigurable Low-power Cryptographic processor based on LFSR for Trusted IoT platforms

Today we see lightweight computer hardware utilized in large volumes, especially with the growing use of IoT devices in homes. However, such devices often ignore security until it is too late and sensitive data breaches have occurred. From here, the importance of finding lightweight cryptographic primitives to secure IoT devices is exponentially increasing, while not impacting the limited resources and limitation of the battery lifetime. In the search for a lightweight cryptographic standard, one must consider how to implement such algorithms optimally. For example, certain parts of an algorithm might be faster in hardware than in software and vice versa. This paper presents a hardware extension supporting the MicroBlaze softcore processor to efficiently implement one of the Lightweight Cryptography (LWC) finalists (TinyJAMBU) on Digilent Nexys A7-100T. The proposed hardware extension consists of a reconfigurable Non-Linear Feedback Shift Register (NLFSR), the central computing part for the authenticated encryption with associated data (AEAD) TinyJAMBU. The proposed NLFSR can run different variants of TinyJAMBU while only consuming 186 mWh in just ten minutes at 100 MHz. The total resources needed to host the proposed NLFSR on the FPGA are 610 LUT and 505 Flip-Flops while executable the binary size is 352 bytes smaller. Therefore, the proposed solution based on the hardware extension is x2.17 times faster than the pure software implementation of the whole TinyJAMBU using MicroBlaze while consuming six mWh more. To our knowledge, this is the first implementation of TinyJAMBU using software/hardware partitioning on FPGA with the softcore processor MicroBlaze.