Abstract—Due to the widespread software piracy and virus attacks, significant efforts have been made to improve security for computer systems. For stand-alone computers, a key observation is that, other than the processor, any component is vulnerable to security attacks. Recently, an execution only memory (XOM) architecture has been proposed to support copy and tamper resistant software. In this design, the program and data are stored in an encrypted format outside the CPU boundary. The decryption is carried out after they are fetched from memory and before they are used by the CPU. As a result, the lengthened critical path causes a serious performance degradation. In this paper, we present an innovative technique in which the cryptography computation is shifted off from the memory access critical path. We propose using a different encryption scheme, namely, “pseudo-one-time pad ” encryption, to produce the instructions and data ciphertext. With some additional on-chip storage, cryptography computations are carried in parallel with memory accesses, minimizing the performance penalty. We performed experiments to study the trade-off between storage size and performance penalty. Our technique reduces the performance overhead from 20.79 percent to 1.28 percent on average for reasonably sized (64KB) on-chip storage. Index Terms—Memory design, hardware/software protection, security and protection. 1

Encryption algorithms commonly use table lookups to perform substitution, which is a confusion primitive. The use of table lookups in this way is especially common in the more recent encryption algorithms, such as the AES finalists like MARS and Twofish, and the AES winner, Rijndael. Workload characterization studies indicate that these algorithms spend a significant fraction of their execution cycles on performing these table lookups, more specifically on effective address calculations. This study . . .

. Manyoftoday's multimedia applications require con#dential video transmission over the Internet. Appropriate encryption methods require a high computational complexity and are likely to become a performance bottleneck within software-only applications. To reduce the computational encryption e#ort, partial video encryption methods have been proposed in the past. Promising approaches are based on data partitioning where the encoded video stream is partitioned into two streams, one containing the most important data, the other one containing the least important data. Encrypting the most important data only can reduce the required computational complexity to 10 - 50 # compared to encryption of the whole data stream. Besides the known standardized DCT based video codecs, scalable codecs become more and more popular. Scalable codecs have the advantage that no additional e#ort is needed to obtain the required data partitioning. In this paper, a novel approach to partial video e...

Abstract. In this paper, the implementation of Berlekamp-Massey algorithm to find the linear complexity for any given sequences is introduced. A new two methods for attacking stream cipher are proposed. The first one is attacking with known combining part using hypothesis test to find the data significant level compromising the appropriate one, while the second method for attacking unknown combining part by finding the behavior (truth table) of the combining part through two algorithms. Once the truth table of the combining part is found, the initial values of the registers can be found in the driving part or drawing the

Abstract- To enhance the security and reliability of the widely-used stream ciphers, a 2-D and a 3-D mesh-knight Algorithm Based Fault Tolerant (ABFT) schemes for stream ciphers are developed which can be universally applied to RC4 and other stream ciphers. Based on the ready-made arithmetic unit in stream ciphers, the proposed 2-D ABFT scheme is able to detect and correct any simple error, and the 3-D mesh-knight ABFT scheme is capable of detecting and correcting up to three errors in an n 2-data matrix with liner computation and bandwidth overhead. The proposed schemes provide one-to-one mapping between data index and check sum group so that error can be located and recovered by easier logic and simple operations.

To enhance the security and reliability of the widely-used stream ciphers, a 2-D and a 3-D mesh-knight Algorithm Based Fault Tolerant (ABFT) schemes for stream ciphers are developed which can be universally applied to RC4 and other stream ciphers. Based on the ready-made arithmetic unit in stream ciphers, the proposed 2-D ABFT scheme is able to detect and correct any simple error, and the 3-D meshknight ABFT scheme is capable of detecting and correcting up to three errors in an n 2-data matrix with liner computation and bandwidth overhead. The proposed schemes provide one-to-one mapping between data index and check sum group so that error can be located and recovered by easier logic and simple operations.

Abstract — In this paper, a mapping between initial states of the Fibonacci and the Galois configurations of NLFSRs is established. We show how to choose initial states for two configurations so that the resulting output sequences are equivalent. Index Terms — Fibonacci NLFSR, Galois NLFSR, initial state, pseudo-random sequence, stream cipher.