MarriageTheoremのこと

_ 新部門が発足して半年しか経っていない時点で部門評価をしようなんて発想した人を内心で（中略）しつつ希少なスーツコスで出勤。

_ しばらくバタバタしていたら、またしてもプレプリントサーバの確認状況がひどいことになってしまった。

_ arXiv:math 10月22日分まで、IACR ePrint 2012/662まで確認済み

_ 気になった論文１：A Measure of Dependence for Cryptographic Primitives Relative to Ideal Functions, Daniel Smith-Tone and Cristina Tone, http://eprint.iacr.org/2012/647

In this work we present a modification of a well-established measure of dependence appropriate for the analysis of stopping times for adversarial processes on cryptographic primitives. We apply this measure to construct generic criteria for the ideal behavior of fixed functions in both the random oracle and ideal permutation setting. More significantly, we provide a nontrivial extension of the notion of hash function indifferentiability, transporting the theory from the status of providing security arguments for protocols utilizing ideal primitives into the more realistic setting of protocol assurance with fixed functions. The methodology this measure introduces to indifferentiability analysis connects the security of a hash function with an indifferentiable mode to the security of the underlying compression function in a quantitative way; thus, we prove that dependence results on cryptographic primitives provide a direct means of determining the practical resistance or vulnerability of protocols employing such primitives.

_ 気になった論文２：How powerful are the DDH hard groups?, Periklis A. Papakonstantinou and Charles W. Rackoff and Yevgeniy Vahlis, http://eprint.iacr.org/2012/653

The question whether Identity-Based Encryption (IBE) can be based on the Decisional Diffie-Hellman (DDH) assumption is one of the most prominent questions in Cryptography related to DDH. We study limitations on the use of the DDH assumption in cryptographic constructions, and show that it is impossible to construct a secure Identity-Based Encryption system using, in a black box way, only the DDH (or similar) assumption about a group. Our impossibility result is set in the generic groups model, where we describe an attack on any IBE construction that relies on oracle access to the group operation of randomly labelled group elements -- a model that formalizes naturally DDH hardness.

The vast majority of existing separation results typically give separation from general primitives, whereas we separate a primitive from a class of number theoretic hardness assumptions. Accordingly, we face challenges in creating an attack algorithm that will work against constructions which leverage the underlying algebraic structure of the group. In fact, we know that this algebraic structure is powerful enough to provide generic constructions for several powerful primitives including oblivious transfer and chosen ciphertext secure public-key cryptosystems (note that an IBE generalizes such systems). Technically, we explore statistical properties of the group algebra associated with a DDH oracle, which can be of independent interest.

_ 気になった論文３：Breaking Another Quasigroup-Based Cryptographic Scheme, Markus Dichtl and Pascale B\"offgen, http://eprint.iacr.org/2012/661

In their paper ``A Quasigroup Based Random Number Generator for Resource Constrained Environments", the authors Matthew Battey and Abhishek Parakh propose the pseudo random number generator LOQG PRNG 256. We show several highly efficient attacks on LOQG PRNG 256.