Merging and Splitting in Cooperative Games: Some (Im-)Possibility Results

Solutions for cooperative games with side-payments can be manipulated by merging a coalition of players into a single player, or, conversely, splitting a player into a number of smaller players. This paper establishes some (im-)possibility results concerning merging- or splitting-proofness of core solutions of balanced and convex games.cooperative games; manipulation; Dutta-Ray solution

Cryptanalysis of LOKI91

In this paper we examine the redesign of LOKI, LOKI91 proposed by Brown et al. First it is shown that there is no characteristic with a probability high enough to do a successful differential attack on LOKI91. Secondly we show that the size of the image of the F-function in LOKI91 is 8\22*2^32. Finally we introduce a chosen plaintext attack that reduces an exhaustive key search on LOKI91 by almost a factor 4 using 2^33+2 chosen plaintexts

Partial and Higher Order Differentials and Applications to the DES

In 1994 Lai considered higher order derivatives of discrete functions andintroduced the concept of higher order differentials. We introduce the conceptof partial differentials and present attacks on ciphers presumably secureagainst differential attacks, but vulnerable to attacks using higher order andpartial differentials. Also we examine the DES for partial and higher orderdifferentials and give a differential attack using partial differentials on DESreduced to 6 rounds using only 46 chosen plaintexts with an expected running time of about the time of 3,500 encryptions. Finally it is shown how to find a minimum nonlinear order of a block cipher using higher order differentials

Iterative Characteristics of DES and S^2-DES

In this paper we show that we are close at the proof that the type of characteristics used by Biham and Shamir in their differential attack on DES are in fact the best characteristics we can find for DES. Furthermore we show that the criteria for the construction of DES-like S-boxes proposed by Kim are insufficient to assure resistance against differential attacks. We show several good iterative characteristics for these S-boxes to be used in differential attacks. Finally we examine the probabilities of the two characteristics used by Biham and Shamir. We found that for some keys we do not get the probabilities used in the attack. We suggest the use of 5 characteristics instead of two in the attack on DES

Cryptanalysis of LOKI

In 1990 Brown, Pieprzyk and Seberry proposed a new encryption primitive, which encrypts and decrypts a 64-bit block of data using a 64-bit key. Furthermore they propose a way to build private versions of LOKI.In this paper we show first that the keyspace of any LOKI-version is only 2^60, not 2^64 as claimed. Therefore there are 15 equivalent keys for every key, that encrypts/decrypts texts the same way. An immediate consequence is, that for the proposed Single Block Hash Mode it is very easy to find collisions. Secondly we do differential cryptanaiysis on LOKI and show that n-round LOKI, n<=14 is vulnerable to this kind of attack, at least in principle. We show that we cannot find a characteristic with a probability high enough to break LOKI with 16 rounds. However one might find a private LOKI-version, that is vulnerable to a differential attack for n=16. Finally we consider differentials versus characteristics for LOKI

Block Ciphers: Analysis, Design and Applications

In this thesis we study cryptanalysis, applications and design of secret key block ciphers. In particular, the important class of Feistel ciphers is studied, which has a number of rounds, where in each round one applies a cryptographically weak function

Selection for resistance against root pathogens in a pea composite cross

The possibility of improving resistance in pea against the root pathogen Aphanomyces euteiches using composite cross as a breeding and selection method was examined. In order to maintain acceptable agricultural features and high yield 6 out of the 8 parental varieties in the present composite-cross were commercially grown varieties. Populations of the composite cross were grown up to five generations with selection pressure in soil heavily infested with pea root pathogens or without selection pressure on soil free of pea root pathogens. Yield of populations of the F9 and F10 generations of the composite cross grown with selection pressure was on average 35% higher than that of the population obtained without selection pressure as well as the average yield of the 8 parentals of the composite cross, which were of similar magnitude. In healthy soil the yield was overall higher than in the pathogen-infested soil, but yield did not differ between the populations from the composite cross with and without selection pressure, which were also similar to the average yield of the 8 different parentals. Recombinant inbred lines (RILs) randomly selected from the F10 population with selection pressure developed 23% less root rot than the corresponding F10 population without selection pressure, when grown in field soil heavily infested with pea root pathogens. Surprisingly, greenhouse pot experiments with pure cultures of the pea root pathogen A. euteiches resulted in higher root disease, in RILs from populations with selection pressure than from corresponding RILs without selection pressure. Problems related to greenhouse screening for resistance is discussed as well as the possibilities of using composite cross as a method to improve resistance against root diseases in grain legumes