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14
Improving Memory Encryption Performance in Secure Processors
 IEEE Transactions on Computers
, 2005
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On analysis and synthesis of (n,k)nonlinear feedback shift registers
 In Proceedings of the Conference on Design Automation and Test in Europe: DATE’08
, 2008
"... Abstract — NonLinear Feedback Shift Registers (NLFSRs) have been proposed as an alternative to Linear Feedback Shift Registers (LFSRs) for generating pseudorandom sequences for stream ciphers. In this paper, we introduce (n,k)NLFSRs which can be considered a generalization of the Galois type of L ..."
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Abstract — NonLinear Feedback Shift Registers (NLFSRs) have been proposed as an alternative to Linear Feedback Shift Registers (LFSRs) for generating pseudorandom sequences for stream ciphers. In this paper, we introduce (n,k)NLFSRs which can be considered a generalization of the Galois type of LFSR. In an (n,k)NLFSR, the feedback can be taken from any of the n bits, and the next state functions can be any Boolean function of up to k variables. Our motivation for considering this type NLFSRs is that their Galois configuration makes it possible to compute each next state function in parallel, thus increasing the speed of output sequence generation. Thus, for stream cipher application where the encryption speed is important, (n,k)NLFSRs may be a better alternative than the traditional Fibonacci ones. We derive a number of properties of (n,k)NLFSRs. First, we demonstrate that they are capable of generating output sequences with good statistical properties which cannot be generated by the Fibonacci type of NLFSRs. Second, we show that the period of the output sequence of an (n,k)NLFSR is not necessarily equal to the length of the largest cycle of its states. Third, we compute the period of an (n,k)NLFSR constructed from several parallel NLFSRs whose outputs are XORed and show how to maximize this period. We also present an algorithm for estimating the length of cycles of states of (n,k)NLFSRs which uses Binary Decision Diagrams for representing the set of states and the transition relation on this set. I.
Performance Impact of Addressing Modes on Encryption Algorithms
, 2001
"... 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 charac ..."
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Cited by 5 (2 self)
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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 . . .
A scalable method for constructing Galois NLFSRs with period 2 n − 1 using crossjoin pairs
 IEEE Trans. on Inform. Theory
"... Abstract. This paper presents a method for constructing nstage Galois NLFSRs with period 2 n − 1 from nstage maximum length LFSRs. We introduce nonlinearity into state cycles by adding a nonlinear Boolean function to the feedback polynomial of the LFSR. Each assignment of variables for which this ..."
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Abstract. This paper presents a method for constructing nstage Galois NLFSRs with period 2 n − 1 from nstage maximum length LFSRs. We introduce nonlinearity into state cycles by adding a nonlinear Boolean function to the feedback polynomial of the LFSR. Each assignment of variables for which this function evaluates to 1 acts as a crossing point for the LFSR state cycle. By adding a copy of the same function to a later stage of the register, we cancel the effect of nonlinearity and join the state cycles back. The presented method requires no extra time steps and it has a smaller area overhead compared to the previous approaches based on crossjoin pairs. It is feasible for large n. However, it has a number of limitations. One is that the resulting NLFSRs can have at most ⌊n/2⌋1 stages with a nonlinear update. Another is that feedback functions depend only on state variables which are updated linearly. The latter implies that sequences generated by the presented method can also be generated using a nonlinear filter generator. 1
Video Encryption Based on Data Partitioning and Scalable Coding  A Comparison
 Comparison,” Lecture Notes in Computer Science vol. 1483/1998, Proc. 5 th Int. Workshop Interactive Distributed Multimedia Systems and Telecommunication Services, IDMS'98, SpringerVerlag Heidelberg
, 1998
"... . 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 softwareonly applications. To reduce the computational encryptio ..."
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. 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 softwareonly 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...
1 Finding Matching Initial States for Equivalent NLFSRs in the Fibonacci and the Galois Configurations
, 903
"... 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 ..."
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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, pseudorandom sequence, stream cipher.
An EquivalencePreserving Transformation of Shift Registers
"... Abstract. The FibonaccitoGalois transformation is useful for reducing the propagation delay of feedback shift registerbased stream ciphers and hash functions. In this paper, we extend it to handle GaloistoGalois case as well as feedforward connections. This makes possible transforming Trivium ..."
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Abstract. The FibonaccitoGalois transformation is useful for reducing the propagation delay of feedback shift registerbased stream ciphers and hash functions. In this paper, we extend it to handle GaloistoGalois case as well as feedforward connections. This makes possible transforming Trivium stream cipher and increasing its keystream data rate by 27 % without any penalty in area. The presented transformation might open new possibilities for cryptanalysis of Trivium, since it induces a class of stream ciphers which generate the same set of keystreams as Trivium, but have a different structure.
2010 International Conference on Multimedia Information Networking and Security Multiple Dimensional Fault Tolerant Schemes for Crypto Stream Ciphers
"... Abstract To enhance the security and reliability of the widelyused stream ciphers, a 2D and a 3D meshknight 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 readymade arithmetic unit in ..."
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Abstract To enhance the security and reliability of the widelyused stream ciphers, a 2D and a 3D meshknight 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 readymade arithmetic unit in stream ciphers, the proposed 2D ABFT scheme is able to detect and correct any simple error, and the 3D meshknight ABFT scheme is capable of detecting and correcting up to three errors in an n 2data matrix with liner computation and bandwidth overhead. The proposed schemes provide onetoone mapping between data index and check sum group so that error can be located and recovered by easier logic and simple operations.
Multiple Dimensional Fault Tolerant Schemes for Crypto Stream Ciphers
"... To enhance the security and reliability of the widelyused stream ciphers, a 2D and a 3D meshknight 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 readymade arithmetic unit in stream ci ..."
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To enhance the security and reliability of the widelyused stream ciphers, a 2D and a 3D meshknight 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 readymade arithmetic unit in stream ciphers, the proposed 2D ABFT scheme is able to detect and correct any simple error, and the 3D meshknight ABFT scheme is capable of detecting and correcting up to three errors in an n 2data matrix with liner computation and bandwidth overhead. The proposed schemes provide onetoone mapping between data index and check sum group so that error can be located and recovered by easier logic and simple operations.