National Institute of Standards and Technology における超伝導研究及び生活

Providing security support for mobile ad-hoc networks is challenging for several reasons: (a) wireless networks are susceptible to attacks ranging from passive eavesdropping to active interfering, occasional break-ins by adversaries may be inevitable in a large time window; (b) mobile users demand "anywhere, anytime" services; (c) a scalable solution is needed for a large-scale mobile network. In this paper, we describe a solution that supports ubiquitous security services for mobile hosts, scales to network size, and is robust against break-ins. In our design, we distribute the certification authority functions through a threshold secret sharing mechanism, in which each entity holds a secret share and multiple entities in a local neighborhood jointly provide complete services. We employ localized certification schemes to enable ubiquitous services. We also update the secret shares to further enhance robustness against break-ins. Both simulations and implementation confirm the effectiveness of our design.

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Providing robust and ubiquitous security support for mobile ad-hoc networks

In this paper we study the long standing problem of information extraction from multiple linear approximations. We develop a formal statistical framework for block cipher attacks based on this technique and derive explicit and compact gain formulas for generalized versions of Matsui’s Algorithm 1 and Algorithm 2. The theoretical framework allows both approaches to be treated in a unified way, and predicts significantly improved attack complexities compared to current linear attacks using a single approximation. In order to substantiate the theoretical claims, we benchmarked the attacks against reduced-round versions of DES and observed a clear reduction of the data and time complexities, in almost perfect correspondence with the predictions. The complexities are reduced by several orders of magnitude for Algorithm 1, and the significant improvement in the case of Algorithm 2 suggests that this approach may outperform the currently best attacks on the full DES algorithm.

Advances in Cryptology – CRYPTO 2004

Radio frequency identification (RFID) is an emerging technology which brings enormous productivity benefits in applications where objects have to be identified automatically This paper presents issues concerning security and privacy of RFID systems which are heavily discussed in public In contrast to the RFID community, which claims that cryptographic components are too costly for RFID tags, we describe a solution using strong symmetric authentication which is suitable for today’s requirements regarding low power consumption and low die-size We introduce an authentication protocol which serves as a proof of concept for authenticating an RFID tag to a reader device using the Advanced Encryption Standard (AES) as cryptographic primitive The main part of this work is a novel approach of an AES hardware implementation which encrypts a 128-bit block of data within 1000 clock cycles and has a power consumption below 9 μA on a 035 μm CMOS process

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Strong Authentication for RFID Systems using the AES Algorithm

Radio frequency identification (RFID) is an emerging technology which brings enormous productivity benefits in applications where objects have to be identified automatically This paper presents issues concerning security and privacy of RFID systems which are heavily discussed in public In contrast to the RFID community, which claims that cryptographic components are too costly for RFID tags, we describe a solution using strong symmetric authentication which is suitable for today's requirements regarding low power consumption and low die-size We introduce an authentication protocol which serves as a proof of concept for authenticating an RFID tag to a reader device using the Advanced Encryption Standard (AES) as cryptographic primitive The main part of this work is a novel approach of an AES hardware implementation which encrypts a 128-bit block of data within 1000 clock cycles and has a power consumption below 9 μA on a 035 μm CMOS process

Strong authentication for RFID systems using the AES algorithm

Let G be a finite graph with vertex set V and edge set E A graph complex on G is an abstract simplicial complex consisting of subsets of E In particular, we may interpret such a complex as a fami 

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Simplicial complexes of graphs

Generalized triangulations and diagonal-free subsets of stack polyominoes

We analyze the security of the CTR + CBC-MAC (CCM) encryption mode. This mode, proposed by Doug Whiting, Russ Housley, and Niels Ferguson, combines the CTR (counter) encryption mode with CBC-MAC message authentication and is based on a block cipher such as AES. We present concrete lower bounds for the security of CCM in terms of the security of the underlying block cipher. The conclusion is that CCM provides a level of privacy and authenticity that is in line with other proposed modes such as OCB.

On the security of CTR + CBC-MAC

In 1996, a new cryptosystem called NTRU was introduced, related to the hardness of finding short vectors in specific lattices. At Eurocrypt 2001, the NTRU Signature Scheme (NSS), a signature scheme apparently related to the same hard problem, was proposed. In this paper, we show that the problem on which NSS relies is much easier than anticipated, and we describe an attack that allows efficient forgery of a signature on any message. Additionally, we demonstrate that a transcript of signatures leaks information about the secret key: using a correlation attack, it is possible to recover the key from a few tens of thousands of signatures. The attacks apply to the recently proposed parameter sets NSS251-3-SHA1-1, NSS347-3-SHA1-1, and NSS503-3-SHA1-1 in [2]. Following the attacks, NTRU researchers have investigated enhanced encoding/verification methods in [11].

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Cryptanalysis of the NTRU Signature Scheme (NSS) from Eurocrypt 2001

We show that the security of the TLS handshake protocol based on RSA can be related to the hardness of inverting RSA given a certain "partial-RSA" decision oracle. The reduction takes place in a security model with reasonable assumptions on the underlying TLS pseudo-random function, thereby addressing concerns about its construction in terms of two hash functions. The result is extended to a wide class of constructions that we denote tagged key-encapsulation mechanisms.

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Jakob Jonsson

Papers

Simplicial complexes of graphs

Generalized triangulations and diagonal-free subsets of stack polyominoes

On the security of CTR + CBC-MAC

Cryptanalysis of the NTRU Signature Scheme (NSS) from Eurocrypt 2001

On the Security of RSA Encryption in TLS