The use of cryptographic hash functions like MD5 or SHA for message authentication has become a standard approach inmanyInternet applications and protocols. Though very easy to implement, these mechanisms are usually based on ad hoc techniques that lack a sound security analysis. We present new constructions of message authentication schemes based on a cryptographic hash function. Our schemes, NMAC and HMAC, are proven to be secure as long as the underlying hash function has some reasonable cryptographic strengths. Moreover we show, in a quantitativeway, that the schemes retain almost all the security of the underlying hash function. In addition our schemes are e cient and practical. Their performance is essentially that of the underlying hash function. Moreover they use the hash function (or its compression function) as a black box, so that widely available library code or hardware can be used to implement them in a simple way, and replaceability of the underlying hash function is easily supported.

Abstract — As mobile ad hoc network applications are deployed, security emerges as a central requirement. In this paper, we introduce the wormhole attack, a severe attack in ad hoc networks that is particularly challenging to defend against. The wormhole attack is possible even if the attacker has not compromised any hosts, and even if all communication provides authenticity and confidentiality. In the wormhole attack, an attacker records packets (or bits) at one location in the network, tunnels them (possibly selectively) to another location, and retransmits them there into the network. The wormhole attack can form a serious threat in wireless networks, especially against many ad hoc network routing protocols and location-based wireless security systems. For example, most existing ad hoc network routing protocols, without some mechanism to defend against the wormhole attack, would be unable to find routes longer than one or two hops, severely disrupting communication. We present a new, general mechanism, called packet leashes, for detecting and thus defending against wormhole attacks, and we present a specific protocol, called TIK, that implements leashes. I.

We introduce a new technique for constructing a family of universal hash functions.

As mobile ad hoc network applications are deployed, security emerges as a central requirement. In this paper, we introduce the wormhole attack, a severe attack against ad hoc routing protocols that is particularly challenging to defend against. We show how an attacker can use the wormhole attack to cripple a range of ad hoc network routing protocols. In the wormhole attack, an attacker records packets (or bits) at one location in the network, tunnels them to another location, and retransmits them there into the network. Most existing ad hoc network routing protocols, without some mechanism to defend them against the wormhole attack, would be unable to find routes longer than one or two hops, severely disrupting communication.

This paper presents a novel cryptographic capability system addressing the security and performance needs of network attached storage systems in which file management functions occur at a different location than the file storage device. In our NASD system file managers issue capabilities to client machines, which can then directly access files stored on the network attached storage device without intervention by a file server. These capabilities may be reused by the client, so that interaction with the file manager is kept to a minimum. Our system emphasizes performance and scalability while separating the roles of decision maker (issuing capabilities) and verifier (validating a capability). We have demonstrated our system with adaptations of both the NFS and AFS distributed file systems using a prototype NASD implementation. Sponsored by DARPA/ITO through ARPA Order D306, and issued by the Indian Head Division, NSWC under contract

With the advent of the Pentium processor parallelization finally became available to Intel based computer systems. One of the design principles of the MD4-family of hash functions (MD4, MD5, SHA-1, RIPEMD-160) is to be fast on the 32-bit Intel processors. This paper shows that carefully coded implementations of these hash functions are able to exploit the Pentium's superscalar architecture to its maximum e#ect: the performance with respect to execution on a non-parallel architecture increases by about 60%. This is an important result in view of the recent claims on the limited data bandwidth of these hash functions.

This paper gives a survey on cryptographic hash functions. It gives an overview of all types of hash functions and reviews design principals and possible methods of attacks. It also focuses on keyed hash functions and provides the applications, requirements, and constructions of keyed hash functions.

Organizations use Web caches to avoid transferring the same data twice over the same path. Numerous studies have shown that forward proxy caches, in practice, incur miss rates of at least 50%. Traditional Web caches rely on the reuse of responses for given URLs. Previous analyses of real-world traces have revealed a complex relationship between URLs and reply payloads, and have shown that this complexity frequently causes redundant transfers to caches. For example, redundant transfers may result if a payload is aliased (accessed via different URLs), or if a resource rotates (alternates between different values) , or if HTTP's cache revalidation mechanisms are not fully exploited. We implement and evaluate a technique known in the literature as Duplicate Transfer Detection (DTD), with which a Web cache can use digests to detect and potentially eliminate all redundant payload transfers. We show how HTTP can support DTD with few or no protocol changes, and how a DTD-enabled proxy cache can interoperate with unmodified existing origin servers and browsers, thereby permitting incremental deployment. We present both simulated and experimental results that quantify the benefits of DTD.

Abstract — As mobile ad hoc network applications are deployed, security emerges as a central requirement. In this paper, we introduce the wormhole attack, a severe attack in ad hoc networks that is particularly challenging to defend against. The wormhole attack is possible even if the attacker has not compromised any hosts, and even if all communication provides authenticity and confidentiality. In the wormhole attack, an attacker records packets (or bits) at one location in the network, tunnels them (possibly selectively) to another location, and retransmits them there into the network. The wormhole attack can form a serious threat in wireless networks, especially against many ad hoc network routing protocols and location-based wireless security systems. For example, most existing ad hoc network routing protocols, without some mechanism to defend against the wormhole attack, would be unable to find routes longer than one or two hops, severely disrupting communication. We present a general mechanism, called packet leashes, for detecting and thus defending against wormhole attacks, and we present a specific protocol, called TIK, that implements leashes. We also discuss topology-based wormhole detection, and show that it is impossible for these approaches to detect some wormhole topologies. Index Terms — Ad hoc networks, computer network security, computer networks, tunneling, wireless LAN, wormhole, packet

Advances in microelectronics, material science and wireless technology have led to the development of sensors that can be used for accurate monitoring of inaccessible environments. Health monitoring, telemedicine, military and environmental monitoring are some of the applications where sensors can be used. The sensors implanted inside the human body to monitor parts of the body are called biosensors. These biosensors form a network and collectively monitor the health condition of their carrier or host. Health monitoring involves collection of data about vital body parameters from different parts of the body and making decisions based on it. This information is of personal nature and is required to be secured. Insecurity may also lead to dangerous consequences. Due to the extreme constraints of energy, memory and computation securing the communication among the biosensors is not a trivial problem. Key distribution is central to any security mechanism. In this paper we propose an approach wherein, biometrics derived from the body are used for securing the keying material. This method obviates the need for expensive computation and avoids unnecessary communication making our approach novel compared to existing approaches.