Pure DDP-Based Cipher: Architecture Analysis, Hardware Implementation Cost and Performance up to 6.5 Gbps

Nikolay Moldovyan¹, Nicolas Sklavos², and Odysseas Koufopavlou²

¹Specialized Center of Program Systems (SPECTR), Russia

²Electrical and Computer Engineering Department, University of Patras, Greece

Abstract: Using Data-Dependent (DD) Permutations (DDP) as main cryptographic primitive, a new 64-bit block cipher is presented, ten-round DDP-64. Since the sum of all outputs of the conventional DDP is a linear Boolean function, non-linear DDP-based operation F is used additionally in DDP-64. The DDP-64 is a pure DDP-based cipher, i. e., it uses only permutations and the XOR operation. The designed cipher uses very simple key scheduling that defines high performance, especially in the case of frequent key refreshing. A novel feature of DDP-64 is the use of the switchable operation preventing the weak keys. The offered high level security strength does not sacrifice the implementation performance of DDP-64. Design and hardware implementation architectures of this cipher are presented. The synthesis results for both Field Programmable Gate Arrays (FPGA) and Application Specific Integrated Circuits (ASIC) implementations prove that DDP-64 is very flexible and powerful new cipher, especially for high speed WLANs and WPANs. The achieved hardware performance up to 6.5 Gbps and the implementation area cost of DDP-64 are compared with other ciphers, used in security layers of wireless protocols (Bluetooth, WAP, OMA, UMTS and IEEE 802.11). From these comparisons, it is proven that DDP-64 is a flexible new cipher with better performance in most of the cases, suitable for wireless communications networks of present and future.

Keywords: Data-dependent permutations, hardware implementation, fast encryption, block cipher, security.

Received August 7, 2003; accepted December 23, 2003