Client puzzles are meant to act as a defense against denial of service (DoS) attacks by requiring a client to solve some moderately hard problem before being granted access to a resource. However, recent client puzzle difficulty definitions (Stebila and Ustaoglu, 2009; Chen et al., 2009) do not ensure that solving n puzzles is n times harder than solving one puzzle. Motivated by examples of puz...

The main emphasis in developing DOS has been on achieving low crosstalk (CT). CT in the order of -30 dB is acceptable in conventional DOS and below that value is hard to achieve. Relatively low drive voltage (or power requirements) is also necessary to optimized DOS. This paper depicts the design of Y-branched digital optical switches (DOS) with optimized on-chip area coverage, reduced driving ...

Client puzzles are meant to act as a defense against denial of service (DoS) attacks by requiring a client to solve some moderately hard problem before being granted access to a resource. However, recent client puzzle difficulty definitions (Stebila and Ustaoglu, 2009; Chen et al., 2009) do not ensure that solving n puzzles is n times harder than solving one puzzle. Motivated by examples of puz...

1 This work was supported by ARO grant 48575-RT-ISP. Abstract A predictive-hashing based Denial-of-Service (DoS) resistant multicast authentication protocol was proposed based upon predictive-hashing, one-way key chain, erasure codes, and distillation codes techniques [4, 5]. It was claimed that this new scheme should be more resistant to various types of DoS attacks, and its worst-case resourc...

Just Fast Keying (JFK) is a simple, efficient and secure key exchange protocol proposed by Aiello et al. (ACM TISSEC, 2004). JFK is well known for its novel design features, notably its resistance to denialof-service (DoS) attacks. Using Meadows’ cost-based framework, we identify a new DoS vulnerability in JFK. The JFK protocol is claimed secure in the Canetti-Krawczyk model under the Decisiona...

| In key-agreement protocols, we have a trade-o between security and availability; if authenticated for reasons of security, the protocol would be more vulnerable to a Denial-of-Service (DoS) attack composed of quite a large number of bogus requests which cost an honest responder a lot. DoS-protection strategies such as network ingress ltering and falling-together (FT) mechanism can make the pr...

This paper addresses protocol susceptibility to denial-of-service attacks. We analyze protocol fragments using Meadows’s cost-based framework [9] to identify sequences of actions that render servers disabled, either due to memory or CPU exhaustion. In particular, we show that the JFK protocol [1] is DoS-resistant when bogus messages are handled in an appropriate way. We also discuss the relatio...

Notch signaling is critical for cell fate decisions during development. Caenorhabditis elegans and vertebrate Notch ligands are more diverse than classical Drosophila Notch ligands, suggesting possible functional complexities. Here, we describe a developmental role in Notch signaling for OSM-11, which has been previously implicated in defecation and osmotic resistance in C. elegans. We find tha...

In this issue of Blood, back-to-back (dos-à-dos) papers by Chiu et al and Yee et al present complementary findings of structural investigations into the interaction between factor VIII (FVIII) and von Willebrand factor (VWF). The binding of FVIII to VWF contributes in a major way to the regulation of hemostasis.

Proxy-network based overlays have been proposed to protect Internet Applications against Denial-of-Service (DoS) attacks by hiding an application’s location. We study how a proxy network’s topology influences the effectiveness of location-hiding. We provide a general analysis of system dynamics under attack, and study how the speed of attack, speed of defense, and proxy network topology affect ...