DPA Resistant AES on FPGA Using Partial DDL

Current techniques to implement Dynamic Differential Logic (DDL), a countermeasure against Differential Power Analysis (DPA) on Field Programmable Gate Arrays (FPGAs) lead to an increase in area consumption of up to factor 11. In this paper we introduce Partial DDL, a technique in which DDL is applied only to a part of the cryptographic hardware implementation. We propose principle rules for Partial DDL to guide the designer in how to split up a circuit into DDL protected and unprotected paths. In order to validate our approach we implemented a lightweight architecture of AES in the Partial Separated Dynamic Differential Logic (Partial SDDL) for FPGAs. The results show that our implementation with Partial SDDL is as resistant to DPA as a full SDDL implementation while it consumes only 76% of the total area occupied by the full SDDL design. This is an area increase of 2.3 times over an unprotected single ended design.