14438478
A Certificate-Based Signature Scheme
In this paper, we propose the security notion of certificate-based signature that uses the same parameters and certificate revocation strategy as the encryption scheme presented at Eurocrypt 2003 by Gentry. Certificate-based signature preserves advantages of certificate-based encryption, such as implicit certification and no private key escrow. We present concrete certificate-based signature schemes derived from pairings on elliptic curves and prove their security in the random oracle model assuming that the underlying group is GDH. Additionally, we propose a concrete delegation-by-certificate proxy signature scheme which is derived from a certificate-based signature scheme after simple modifications. Our proxy scheme is provably secure in the random oracle model under the security notion defined by Boldyreva, Palacio and Warinschi.
8508201
Cryptanalysis of Some Group-Oriented Proxy Signature Schemes
A proxy signature scheme allows an entity to delegate its signing power to another entity. Since the notion of proxy signatures was first introduced, many proxy signature schemes and various extensions have been considered. As an example, the notion of threshold proxy signature or proxy multi-signature was introduced as a group-oriented variant. In this paper, we show that the threshold proxy signature scheme proposed by Hsu and Wu, and the proxy multi-signature schemes independently proposed by Chen et al. and Hsu et al. are all insecure against the malicious original singer(s). Our result provides a simple example that the way to put the secret parts together should be carefully considered.
26868655
Complexity of the generalized conjugacy problem
Recently, the generalized conjugacy problem(GCP) in braid groups was introduced as a candidate for cryptographic one-way function. A GCP in a braid group can be transformed into a GCP in a general linear group by the Burau representation. We study the latter problem induced in this way.
6256815
Cryptanalysis of the Public-Key Encryption Based on Braid Groups
At CRYPTO 2000, a new public-key encryption based on braid groups was introduced. This paper demonstrates how to solve its underlying problem using the Burau representation. By this method, we show that the private-key can be recovered from the public-key for several parameters with significant probability in a reasonable time. Our attack can be mounted directly on the revised scheme mentioned at ASIACRYPT 2001 as well. On the other hand, we give a new requirement for secure parameters against our attack, which more or less conflicts with that against brute force attack.
799734
Efficient multicast packet authentication using signature amortization
We describe a novel method for authenticating multicast packets that is robust against packet loss. Our main focus is to minimize the size of the communication overhead required to authenticate the packets. Our approach is to encode the hash values and the signatures with Rabin's Information Dispersal Algorithm (IDA) to construct an authentication scheme that amortizes a single signature operation over multiple packets. This strategy is especially efficient in terms of space overhead, because just the essential elements needed for authentication (i.e., one hash per packet and one signature per group of packets) are used in conjunction with an erasure code that is space optimal. To evaluate the performance of our scheme, we compare our technique with four other previously proposed schemes using analytical and empirical results. Two different bursty loss models are considered in the analyses.
404376
Power-aware deterministic block allocation for low-power way-selective cache structure
This paper proposes a power-aware cache block allocation algorithm for the way-selective set-associative cache on embedded systems to reduce energy consumption without additional delay or performance degradation. For this goal, way selection logic and specialized replacement policy are designed to enable only one way of set-associative cache as in the direct-mapped cache. Overall cache access time becomes almost the same as that of a conventional set associative cache with accessing additional way selection logic. Because data array can be accessed without waiting for tag comparison, multiplexer delay can be removed totally. The simulation result shows that the proposed architecture can reduce a per access power consumption by 59% over conventional set-associative caches with average 0.06% of negligible performance loss.
14413427
Memory Footprint Reduction with Quasi-Static Shared Libraries in MMU-less Embedded Systems
Despite a rapid decrease in the price of solid state memory devices, system memory is still a very precious resource in embedded systems. The use of shared libraries is known to be effective in significantly reducing memory usage. Unfortunately, many resource-constrained embedded systems lack MMU, making it extremely difficult to support this technique. To address this problem, we propose a novel shared library scheme called the quasi-static shared library. In quasi-static shared libraries, global symbols are bound to pseudo-addresses at linking time and the actual physical addresses are bound at loading time. This scheme is made possible by emulating MMU’s memory mapping feature with a Data Section Base Register (DSBR) and a Data Section Base Table (DSBT). Quasi-static shared libraries do not require symbol tables which take up time and space at runtime. We have implemented the proposed scheme in a commercial ADSL (Asymmetric Digital Subscriber Line) home network gateway and conducted a series of experiments measuring its memory usage and performance overhead. The result is drastic: a 35% reduction in flash memory usage and a 10% reduction in RAM usage. These results were achieved with only a negligible performance penalty of less than 4%. Even though this scheme was applied to uClinux-based embedded systems, it can be used for any MMU-less real-time operating system.
45167088
Moving Object Inference Engine and Applying to Battlefield
42838112
Trusted Identity and Session Management Using Secure Cookies
The concept of federated identity management is increasingly coming to use in order to bring Service Providers closer to customers. Users are being provided an enriched experience while carrying out business on the Web at reduced overhead and improved customer service. The idea of maintaining a single profile and gaining access to multiple services has been accepted well by the customers. However, the benefits of breaking through just one set of credentials to gain access to multiple services has made the concept of Federated Identity Management of high interest to malicious users. In this paper, we analyze the structure of a generic Federated Identity Management System and explore the .NET Passport framework in depth. We explore the current security mechanisms adopted by the .NET Passport and identify potential security weaknesses. We then propose our new approaches to enhance the security services in .NET Passport by using Secure Cookies. Our approaches are transparent to and compatible with the current .NET Passport server. Finally, we prove the feasibility by implementing our ideas in a real system.