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ispartof: Journal of Computer Science and Technology status: accepted

This paper presents a reconfigurable hardware architecture for Public-key cryptosystems. By changing the connections of coarse grain Carry-Save Adders (CSAs), the datapath provides a high performance for both RSA and Elliptic Curve Cryptography (ECC). In addition, we introduce another reconfigurability for the flip-flops in order to make the best of hardware resources. The results of FPGA implementation show that better performance is obtained for ECC on the same hardware platform. ispartof: pages:347-357 ispartof: Lecture Notes in Computer Science vol:3985 pages:347-357 ispartof: location:NETHERLANDS, Delft Univ Technol, Delft status: published

This paper presents a hardware architecture for UNIX password cracking using Hellman's time-memory trade-off; it is the first hardware design for a key search machine based on the rainbow variant proposed by Oechslin. The implementation target is the Berkeley BEE2 FPGA platform which can run at 400 million password calculations/second. Our design targets passwords of length 48 bits (out of 56). This means that with one BEE2 module the precomputation for one salt takes about 8 days, resulting in a storage of 56 Gigabyte. For the precomputation of all salts in one year we would need 92 BEE2 modules. Recovering an individual password requires a few minutes on a Virtex-4 FPGA. ispartof: pages:323-334 ispartof: Lecture Notes in Computer Science vol:3985 pages:323-334 ispartof: location:NETHERLANDS, Delft Univ Technol, Delft status: published

Implementing public-key cryptography on platforms with limited resources, such as microprocessors, is a challenging task. Hardware/software co-design is often the only answer to implement the computationally intensive operations with limited memory and power at an acceptable speed. This contribution describes such a solution for Hyperelliptic Curve Cryptography (HECC). The proposed hardware/software co-design of the HECC system was implemented and co-simulated using the CEZEL design environment [3]. As a low-cost platform, we chose an 8-bit 8051 microprocessor to which one small hardware co-processor was added for field multiplication. We show that the Jacobian scalar multiplication can be computed in 2.488 sec at 12 MHz on this platform if a minimal hardware module is added i.e. a hardware multiply-add unit. This optimal solution provides a factor of 26 speed-up over a software-only solution. ispartof: pages:106-118 ispartof: Lecture Notes in Computer Science vol:3659 pages:106-118 ispartof: CHES 2005 location:SCOTLAND, Edinburgh date:29 Aug - 1 Sep 2005 status: published

In the past thirty years, cryptology has evolved from a secret art to a modern science. Weaker algorithms and algorithms with short keys are disappearing, political controls of cryptography have been reduced, and secure cryptography is becoming more and more a commodity. Moreover, implementations are being becoming more secure as well. This progress may lead to the belief that the cryptography problem is "solved." However, this article discusses some of the challenging problems ahead in the area of cryptographic algorithms and protocols. We also explain how the ECRYPT Network of Excellence (www.ecrypt.eu.org) tries to address some of the challenges by bringing together 250 European researchers in the area of cryptology and the related area of watermarking. ispartof: Lecture Notes in Computer Science vol:3352 pages:1-15 ispartof: location:ITALY, Amalfi status: published

This work proposes a compact implementation of the AES S-box using composite field arithmetic in GF(((2^2)^2)^2). It describes a systematic exploration of different choices for the irreducible polynomials that generate the extension fields. It also examines all possible transformation matrices that map one field representation to another. We show that the area of Satoh's S-box, which is the most compact to our knowledge, is at least 5% away from an optimal solution. We implemented this optimal solution and Satoh's design using a 0.18 µm standard cell library. ispartof: pages:323-333 ispartof: Lecture Notes in Computer Science vol:3376 pages:323-333 ispartof: location:CA, San Francisco status: published

Mixing addition modulo 2(n) (+) and exclusive-or (E)) have a host of applications in symmetric cryptography as the operations are fast and nonlinear over GF(2). We deal with a frequently encountered equation (x + y) circle plus ((x circle plus alpha) + (y circle plus beta)) = gamma. The difficulty of solving an arbitrary system of such equations - named differential equations of addition (DEA) - is an important consideration in the evaluation of the security of many ciphers against differential attacks. This paper shows that the satisfiability of an arbitrary set of DEA - which has so far been assumed hard for large n - is in the complexity class P. We also design an efficient algorithm to obtain all solutions to an arbitrary system of DEA with running time linear in the number of solutions. Our second contribution is solving DEA in an adaptive query model where an equation is formed by a query (alpha, beta) and oracle output gamma. The challenge is to optimize the number of queries to solve (x + y) circle plus ((x circle plus alpha) + (y circle plus beta)) = gamma. Our algorithm solves this equation with only 3 queries in the worst case. Another algorithm solves the equation (x+y) circle plus (x + (y circle plus beta)) = gamma with (n - t - 1) queries in the worst case (t is the position of the least significant '1' of x), and thus, outperforms the previous best known algorithm by Muller - presented at FSE '04 - which required 3(n - 1) queries. Most importantly, we show that the upper bounds, for our algorithms, on the number of queries match worst case lower bounds. This, essentially, closes further research in this direction as our lower bounds are optimal. Finally we describe applications of our results in differential cryptanalysis. ispartof: Lecture Notes in Computer Science vol:3574 pages:75-88 ispartof: ACISP 2005 date:July 04-06, 2005 status: published

ispartof: pages:314-324 ispartof: Lecture Notes in Computer Science vol:2259 pages:314-324 ispartof: SAC 2001 date:16 Aug - 17 Aug 2001 status: published

This paper describes the state of the art for cryptographic primitives that are used for protecting the authenticity of information: cryptographic hash functions and digital signature schemes; the first class can be divided into Manipulation Detection Codes (MDCs, also known as one-way and collision resistant hash functions) and Message Authentication Codes (or MACs). The theoretical background is sketched, but most attention is paid to overview the large number of practical constructions for hash functions and to the recent developments in their cryptanalysis. It is also explained to what extent the security of these primitives can be reduced in a provable way to realistic assumptions. ispartof: Lecture Notes in Computer Science vol:1528 pages:49-104 ispartof: location:BELGIUM, LEUVEN status: published

This paper provides an overview of the state of the art in the design of cryptographic algorithms. It reviews the different type of algorithms for encryption and authentication and explains the principles of stream ciphers, block ciphers, hash functions, public-key encryption algorithms, and digital signature schemes. Subsequently the design and evaluation procedures for cryptographic algorithms are discussed. ispartof: Lecture Notes in Computer Science vol:1521 pages:204-221 ispartof: SOFSEM 1998 date:November 21-27, 1998 status: published

Boolean functions that satisfy higher order propagation criteria are studied. A complete characterization is given of the autocorrelation function and Walsh spectrum of second order functions. The number of second order functions satisfying PC(k) is related to a problem in coding theory and can be computed explicitly for k = 1, n - 1 and n. A new interpretation of the number of balanced second order functions is given and a class of functions showing interesting properties is discussed. ispartof: Lecture Notes in Computer Science vol:547 pages:141-152 ispartof: EUROCRYPT 1991 date:April 08-11, 1991 status: published

The relation between the Walsh-Hadamard transform and the auto-correlation function of Boolean functions is used to study propagation characteristics of these functions. The Strict Avalanche Criterion and the Perfect Nonlinearity Criterion are generalized in a Propagation Criterion of degree k. New properties and constructions for Boolean bent functions are given and also the extension of the definition to odd values of n is discussed. New properties of functions satisfying higher order SAC are derived. Finally a general framework is established to classify functions according to their propagation characteristics if a number of bits is kept constant. ispartof: Lecture Notes in Computer Science vol:473 pages:161-173 ispartof: EUROCRYPT 1990 date:May 21-24, 1990 status: published

The main contribution of this paper is a new approach to χ2 analyses of block ciphers in which plaintexts are chosen in a manner similar to that in a square/saturation attack. The consequence is a faster detection of χ2 correlation when compared to conventional χ2 cryptanal- ysis. Using this technique we (i) improve the previously best-known χ2 attacks on 2- and 4-round RC6, and (ii) mount the first attacks on the MRC6 and ERC6 block ciphers. The analyses of these fast primitives were also motivated by their low diffusion power and, in the case of MRC6 and ERC6, their large block sizes, that favour their use in the construction of compression functions. Our analyses indicate that up to 98 rounds of MRC6 and 44 rounds of ERC6 could be attacked.

Threat analysis of a web application can lead to a wide variety of identified threats. Some of these threats will be very specific to the application; others will be more related to the underlying infrastructural software, such as the web or application servers, the database, the directory server and so forth. This paper analyzes the threats that can be related to the use of web services technology in a web application. It is part of a series of papers, written by different academic teams, that each focus on one particular technological building block for web applications. ispartof: pages:131-144 ispartof: Communications and Multimedia Security vol:175 pages:131-144 ispartof: IFIP TC-6 TC-11 Conference on Communications and Multimedia Security location:Windermere, The Lake District, United Kingdom date:15 Sep - 18 Sep 2004 status: published

© Springer-Verlag Berlin Heidelberg 1995. In this paper we present an improvement of the differential attack on hash functions based on block ciphers. By using the specific properties of the collision attack on hash functions, we can greatly reduce the work factor to find a pair that follows the characteristic. We propose a new family of differential characteristics that is especially useful in combination with our improvement. Attacks on a hash function based on DES variants reduced to 12, 13 or 15 rounds become faster than brute force collision attacks. ispartof: pages:242-248 ispartof: Lecture Notes in Computer Science vol:1008 pages:242-248 ispartof: FSE 1994 date:14 Dec - 16 Dec 1994 status: published