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Improving resistance to differential cryptanalysis and the redesign of LOKI
 ADVANCES IN CRYPTOLOGY  ASIACRYPT'91, VOLUME 739, LECTURE NOTES IN COMPUTER SCIENCE
, 1993
"... Differential Cryptanalysis is currently the most powerful tool available for analysing block ciphers, and new block ciphers need to be designed to resist it. It has been suggested that the use of Sboxes based on bent functions, with a at XOR profile, would be immune. However our studies of differen ..."
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Cited by 41 (13 self)
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Differential Cryptanalysis is currently the most powerful tool available for analysing block ciphers, and new block ciphers need to be designed to resist it. It has been suggested that the use of Sboxes based on bent functions, with a at XOR profile, would be immune. However our studies of differential cryptanalysis, particularly applied to the LOKI cipher, have shown that this is not the case. In fact, this results in a relatively easily broken scheme. We show that an XOR pro le with carefully placed zeroes is required. We also show that in order to avoid some variant forms of differential cryptanalysis, permutation P needs to be chosen to prevent easy propagation of a constant XOR value back into the same Sbox. We redesign the LOKI cipher to form LOKI91, to illustrate these results, as well as to correct the key schedule to remove the formation of equivalent keys. We conclude with an overview of the security of the new cipher.
Cryptographic Hash Functions: A Survey
, 1995
"... This paper gives a survey on cryptographic hash functions. It gives an overview of all types of hash functions and reviews design principals and possible methods of attacks. It also focuses on keyed hash functions and provides the applications, requirements, and constructions of keyed hash functions ..."
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Cited by 35 (7 self)
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This paper gives a survey on cryptographic hash functions. It gives an overview of all types of hash functions and reviews design principals and possible methods of attacks. It also focuses on keyed hash functions and provides the applications, requirements, and constructions of keyed hash functions.
Key Scheduling in DES Type Cryptosystems
 in Advances in Cryptology: Auscrypt '90 (Lecture Notes in Computer Science
, 1990
"... This paper reviews some possible design criteria for the key schedule in a DES style cryptosystem. The key schedule involves a Key Rotation component, and the permutation PC2. Together these provide for a diffusion of dependency ofciphertext bits on key bits. Some empirical rules which seem to accou ..."
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Cited by 10 (2 self)
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This paper reviews some possible design criteria for the key schedule in a DES style cryptosystem. The key schedule involves a Key Rotation component, and the permutation PC2. Together these provide for a diffusion of dependency ofciphertext bits on key bits. Some empirical rules which seem to account for the derivation of the key schedule used in the DES are first presented. Anumber of trials were run with various key schedules, and some further design rules were derived. An alternative form of key schedule was then tested. This used either a null PC2, or one in which permutations only occurred within the inputs to a given Sbox, and a much larger rotation schedule than used in the DES. This was found to be as effective as the key schedule used in the current DES, and is proposed for use in new cryptosystems. 1.
Practical and Secure Message Authentication
 In Series of Annual Workshop on Selected Areas in Cryptography (SAC
, 1995
"... Use of encryption algorithms in message authentication is replaced by secure hash functions which are often faster than encryption algorithms. Tsudik [14] has proposed three methods on message authentication which are only based on oneway hash functions and use some keys to make them secure. In thi ..."
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Cited by 6 (3 self)
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Use of encryption algorithms in message authentication is replaced by secure hash functions which are often faster than encryption algorithms. Tsudik [14] has proposed three methods on message authentication which are only based on oneway hash functions and use some keys to make them secure. In this paper, we give a set of practical methods, each of which uses a fast collision free hash function (such as MD5) and provides secure message authentication. The idea of the proposed methods is almost similar to that of Tsudik's, but we are able to reduce the key length eight times compared to the Tsudik's constructions, while maintaining the same security. In our methods, the secret key is added using exclusiveor or assign operators (instead of concatenation) to make them faster. We also have proved that our methods belong to the Secure Keyed OneWay Hash Function (SKOWHF) group, if the underlying hash function is secure. 1 Introduction In today's communication, existence of a fast method...
On the Design of Permutation P in DES Type Cryptosystems
 Advances in Cryptology: Proceedings of EUROCRYPT ’89
, 1990
"... This paper reviews some possible design criteria for the permutation P in a DES style cryptosystem. These permutations provide the diffusion component in a substitutionpermutation network. Some empirical rules which seem to account for the derivation of the permutation used in the DES are first pre ..."
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Cited by 6 (2 self)
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This paper reviews some possible design criteria for the permutation P in a DES style cryptosystem. These permutations provide the diffusion component in a substitutionpermutation network. Some empirical rules which seem to account for the derivation of the permutation used in the DES are first presented. Then it is noted that these permutations may be regarded as latinsquares which link the outputs of Sboxes to their inputs at the next stage. A subset of these with an extremely regular structure, and which perform well in a dependency analysis are then presented and suggested for use in future schemes of both current and extended versions of the DES. 1.
IMPROVEMENT OF DATA PROCESSING SECURITY BY MEANS OF FAULT TOLERANCE
 PROCEEDINGS OF THE 14TH NATIONAL COMPUTER SECURITY CONFERENCE (NCSC’14)
, 1991
"... This paper discusses various different solutions to the problem of reliable processing of confidential information. One of the major difficulties of this problem comes from the fact that conventional techniques for achieving reliability, on the one hand, and security on the other, tend to be in oppo ..."
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Cited by 5 (1 self)
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This paper discusses various different solutions to the problem of reliable processing of confidential information. One of the major difficulties of this problem comes from the fact that conventional techniques for achieving reliability, on the one hand, and security on the other, tend to be in opposition to each other. The different solutions presented here have been classified in three distinct types: two are related to classical security techniques (protection, and encryption) and the third is a new technique, the fragmentationredundancyscattering technique, which it is claimed demonstrates a potentially advantageous unified approach to the provision of reliability and security, based on fault tolerance. Finally, a qualitative comparison of these solutions is given, taking into account both dependability, openness and performance criteria.
Steganography: Its History and Its Application to Computer Based Data Files
, 1995
"... Steganography is the science of hiding data in otherwise plain text or images. This document is split into two sections. Section one gives a brief history of the use of steganography by mankind. It describes interesting events in history where steganography was used to great or sometimes disastrous ..."
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Cited by 5 (0 self)
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Steganography is the science of hiding data in otherwise plain text or images. This document is split into two sections. Section one gives a brief history of the use of steganography by mankind. It describes interesting events in history where steganography was used to great or sometimes disastrous effect. Section two describes some applications that exist on computer which apply steganographic techniques to allow a user to hide information in data files. 1. STEGANOGRAPHY PAST AND PRESENT 4 1.1 INTRODUCTION 5 1.2 HISTORY OF STEGANOGRAPHY 5 1.2.1 ANCIENT TIMES 6 1.2.2 MIDDLE AGES 7 1.2.3 MODERN TIMES 10 1.3 STEGANOGRAPHY ON COMPUTER 12 2. REVIEW OF STEGANOGRAPHIC SOFTWARE 14 2.1 INTRODUCTION 15 2.2 MANDELSTEG BY HENRY HASTUR 15 2.2.1 USER INTERFACE 15 2.2.2 HOW IT IS DONE 16 2.2.3 DISCUSSION 17 2.3 STEG BY THE JPEG GROUP 17 2.3.1 USER INTERFACE 18 2.3.2 HOW IT IS DONE 18 2.3.3 DISCUSSION 19 2.4 STOOLS BY ANDREW BROWN 19 2.4.1 USER INTERFACE 20 2.4.2 HOW IT'S DONE 21 2.4.3 DISC...
New Tests Of Random Numbers For Simulations In Physical Systems
, 1994
"... The aim of this Thesis is to present five new tests for random numbers, which are widely used e.g. in computer simulations in physics applications. The first two tests, the cluster test and the autocorrelation test, are based on analogies to the twodimensional Ising model. The next two, the random ..."
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Cited by 4 (0 self)
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The aim of this Thesis is to present five new tests for random numbers, which are widely used e.g. in computer simulations in physics applications. The first two tests, the cluster test and the autocorrelation test, are based on analogies to the twodimensional Ising model. The next two, the random walk test and the nblock test, are based on studies of random walks, and the condition number test presented last uses some results of Gaussian distributed random matrices. Studies with several commonly used pseudorandom number generators reveal that the cluster test is particularly powerful in finding periodic correlations on bit level, and that the autocorrelation test, the random walk test, and the nblock test are very effective in detecting shortranged correlations. The results of the condition number test are mostly inconclusive, however. By means of the tests presented in this work, two important results are found. First, we show quantitatively that the reason for erroneous results ...
Keyed Hash Functions
 in Cryptography: Policy and Algorithms Conference
, 1996
"... . We give a new definition of keyed hash functions and show its relation with strongly universal hash functions and Cartesian authentication codes. We propose an algorithm for a secure keyed hash function and present preliminary result on its performance. The algorithm can be used for fast (about tw ..."
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Cited by 3 (0 self)
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. We give a new definition of keyed hash functions and show its relation with strongly universal hash functions and Cartesian authentication codes. We propose an algorithm for a secure keyed hash function and present preliminary result on its performance. The algorithm can be used for fast (about twice the speed of MD5) and secure message authentication. 1 Introduction Hash functions were introduced in early 1950's [20]. The original aim was to have functions that can uniformly map a large collection of messages into a small set of message digests (or hash values). A useful application of hash functions is for error detection. Appending message digest to the message allows detection of errors during transmission. In the receiving end, the hash value of the received message is recalculated and compared with the received hash value. If they do not match, an error has occurred. This detection is only for random errors. An active spoofer may intercept a message, modify it as he wishes, an...
M.: New language operations in formal language theory
 Schedae Informaticae
"... Abstract. Stringology represents a modern part of the formal language theory, which deals with strings, languages and operations on them. It introduces many new language operations, which can be divided into two groups – insertion and deletion operations. Some of these operations are described in [1 ..."
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Cited by 2 (0 self)
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Abstract. Stringology represents a modern part of the formal language theory, which deals with strings, languages and operations on them. It introduces many new language operations, which can be divided into two groups – insertion and deletion operations. Some of these operations are described in [1]. This paper presents these operations and some of their properties. Especially, closure properties are studied here. New algorithms that construct finite automata accepting languages resulting from some of these operations are described here. We actually demonstrate by designing these algorithms, that the family of regular languages is closed under these operations.