Design of High Performance MIPS Cryptography Processor Based on T-DES Algorithm

ABSTRACT The paper describes the design of high performance MIPS Cryptography processor based on triple data encryption standard. The organization of pipeline stages in such a way that pipeline can be clocked at high frequency. Encryption and Decryption blocks of triple data encryption standard (T-DES) crypto system and dependency among themselves are explained in detail with the help of block diagram. In order to increase the processor functionality and performance, especially for security applications we include three new 32-bit instructions LKLW, LKUW and CRYPT. The design has been synthesized at 40nm process technology targeting using Xilinx Virtex-6 device. The overall MIPS Crypto processor works at 209MHz. Keywords ALU, register file, pipeline, memory, T-DES, throughput 1. INTRODUCTION oday’s digital world, Cryptography is the art and science that deals with the principles and methods for keeping message secure. Encryption is emerging as a disintegrable part of all communication networks and information processing systems, involving transmission of data. Encryption is the transformation of plain data (known as plaintext) into inintengible data (known as cipher text) through an algorithm referred to as cipher. MIPS architecture employs a wide range of applications. The architecture remains the same for all MIPS based processors while the implementations may differ [1]. The proposed design has the feature of 32-bit asymmetric and symmetric cryptography system as a security application. There is a 16- bit RSA cryptography MIPS cryptosystem have been previously designed [2]. There are the small adjustments and minor improvement in the MIPS pipelined architecture design to protect data transmission over insecure medium using authenticating devices such as data encryption standard [DES], Triple-DES and advanced encryption standard [AES] [3]. These cryptographic devices use an identical key for the receiver side and sender side. Our design mainly includes the symmetric cryptosystem into MIPS pipeline stages. That is suitable to encrypt large amount data with high speed. The MIPS is simply known as Millions of instructions per second and is one of the best RISC (Reduced Instruction Set Computer) processor ever designed. High speed MIPS processor possessed Pipeline architecture for speed up processing, increase the frequency and performance of the processor. A MIPS based RISC processor was described in [4]. It consist of basic five stages of pipelining that are pipelined processor is shown in Fig.1 which containInstruction Fetch, Instruction Decode, Instruction Execution, Memory access, write back. These five pipeline stages generate 5 clock cycles processing delay and several Hazard during the operation [2]. These pipelining Hazard are eliminates by inserting NOP (No Operation Performed) instruction which generate some delays for the proper execution of instruction [4]. The pipelining Hazards are of three type’s data, structural and control hazard. These hazards are handled in the MIPS processor by the implementation of forwarding unit, Pre-fetching or Hazard detection unit, branch and jump prediction unit [2]. Forwarding unit is used for preventing data hazards which detects the dependencies and forward the required data from the running instruction to the dependent instructions [5]. Stall are occurred in the pipelined architecture when the consecutive instruction uses the same operand of the instruction and that require more clock cycles for execution and reduces performance. To overcome this situation, instruction pre-fetching unit is used which reduces the stalls and improve performance. The control hazard are occurs when a branch prediction is mistaken or in general, when the system has no mechanism for handling the control hazards [5]. The control hazard is handled by two mechanisms: Flush mechanism and Delayed jump mechanism. The branch and jump prediction unit uses these two mechanisms for preventing control hazards. The flush mechanism runs instruction after a branch and flushes the pipe after the misprediction [5]. Frequent flushing may increase the clock cycles and reduce performance. In the delayed jump mechanism, to handle the control hazard is to fill the pipe after the jump instruction with specific numbers of NOP’s [5]. The branch and jump prediction unit placement in the pipelining architecture may affect the critical or longest path. To detecting the longest path and improving the hardware that resulting minimum clock period and is the standard method of increasing the performance of the processor. To further speed up processor and minimize clock period, the design incorporates a high speed hybrid adder which employs both carry skip and carry select techniques with in the ALU unit to handle the additions. This paper is organized as follows. The system architecture hardware design and implementation are explained in Section II. Instruction set of MIPS including new instructions in detail with corresponding diagrams shown in sub-sections. Hardware implementation design methodology is explained in section III. The experimental results of pipeline stages are shown in section IV. Simulation results of encrypted MIPS pipeline processor and their Verification & synthesis report are describes in sub sections. The conclusions of paper are described in section V.