Bruce Schneier is without question one of the leading computer security professionals alive today. A true renaissance man when it comes to IT security, he has been involved in the creation of a host of cryptographic algorithms (for example, Blowfish, Twofish, and Threefish); has written several books on cryptography and security topics, the most recent of which is Data and Goliath: The Hidden B...

With the explosive growth of internet technology robust methods are being developed to protect the proprietary rights of the multimedia. In this paper, an invisible watermarking technique is proposed, to embed multiple binary watermarks into digital images based on the concept of Visual Cryptography (VC). Unlike traditional watermarking schemes, the watermarks are not embedded directly into the...

We consider the following problem: two nodes want to reliably communicate in a dynamic multihop network where some nodes have been compromised, and may have a totally arbitrary and unpredictable behavior. These nodes are called Byzantine. We consider the two cases where cryptography is available and not available. We prove the necessary and sufficient condition (that is, the weakest possible co...

Wireless sensor networks (WSNs) are often deployed in potentially adverse or even hostile environment so that there are concerns on security issues in these WSNs. Sensor nodes with resource-constrained make security applications a challenging problem. Key agreement is a fundamental security service in WSNs, which enables sensor nodes to communicate securely with each other using cryptographic t...

Sampling integers with Gaussian distribution is a fundamental problem that arises in almost every application of lattice cryptography, and it can be both time consuming and challenging to implement. Most previous work has focused on the optimization and implementation of integer Gaussian sampling in the context of specific applications, with fixed sets of parameters. We present new algorithms f...

Cryptographic hardware has found many uses in ubiquitous and pervasive security devices with a small form factor, e.g. SIM cards, smart cards, electronic security tokens, and soon even RFIDs. With applications in banking, telecommunication, healthcare, ecommerce and entertainment, these devices use cryptography to provide security services like authentication, identification and confidentiality...

One of the fundamental problems of public key cryptography is protecting the private key. Private keys are too long to be remembered by the user, and storing them in the device which performs the private key operation is insecure as long as the device is subject to capture. In this paper, we propose server-assisted protocols for the ElGamal signature scheme which make the system capture resilie...

Computational notions of entropy (a.k.a. pseudoentropy) have found many applications, including leakage-resilient cryptography, deterministic encryption or memory delegation. The most important tools to argue about pseudoentropy are chain rules, which quantify by how much (in terms of quantity and quality) the pseudoentropy of a given random variable X decreases when conditioned on some other v...

The feature of non-infrastructure support in a wireless ad hoc network (WANET) makes it suffer from various attacks. Moreover, user authentication is the first safety barrier in a network. A mutual trust is achieved by a protocol which enables communicating parties to authenticate each other at the same time and to exchange session keys. For the resource-constrained WANET, an efficient and ligh...

A recent trend in cryptography is to protect data and computation against various side-channel attacks. Dziembowski and Faust (TCC 2012) have proposed a general way to protect arbitrary circuits against any continual leakage assuming that: (i) the memory is divided into the parts, which leaks independently (ii) the leakage in each observation is bounded (iii) the circuit has an access to a leak...