Group communication can benefit from Internet Protocol (IP) multicast protocol to achieve efficient exchange of messages. However, IP multicast does not provide any mechanisms for authentication. In literature, many solutions to solve this problem were presented. It has been shown that Wong and Lam protocol is the only protocol that can resist both packet loss and pollution attacks. In contrast...

This paper studies ways to backdoor lattice-based systems following Young and Yung’s work on backdooring RSA and discrete-log based systems. For the NTRU encryption scheme we show how to build a backdoor and to change the system so that each ciphertext leaks information about the plaintext to the owner of the backdoor. For signature schemes the backdoor leaks information about the signing key t...

The purpose of this paper is to compare side-by-side the NTRU and BGV schemes in their non-scale invariant (messages in the lower bits), and their scale invariant (message in the upper bits) forms. The scale invariant versions are often called the FV and YASHE schemes. As an additional optimization, we also investigate the affect of modulus reduction on the scale-invariant schemes. We compare t...

The continuous dependence on electronic media has radically changed our interactions, many of which are now performed online. In many occasions users need to authenticate to remote machines, but the hostile environment of the Internet may severely expose users and service providers. To counter these shortcomings, strong authentication is pushed forward. As a means to authenticate individuals, b...

A PIR scheme is a scheme that allows an user to get an element of a database without giving any information about what part of the database he is interested in. In this paper we present a lattice-based PIR scheme, using an NTRU-like approach, in which the computational cost is a few thousand bit-operations per bit in the database. This improves the protocol computational performance by two orde...

We describe plausible lattice-based constructions with properties that approximate the soughtafter multilinear maps in hard-discrete-logarithm groups, and show an example application of such multi-linear maps that can be realized using our approximation. The security of our constructions relies on seemingly hard problems in ideal lattices, which can be viewed as extensions of the assumed hardne...

The security of many cryptographic schemes has been based on special instances of the Learning with Errors (LWE) problem, e.g., Ring-LWE, LWE with binary secret, or LWE with ternary error. However, recent results show that some subclasses are weaker than expected. In this work we show that LWE with binary error, introduced by Micciancio and Peikert, is one such subclass. We achieve this by appl...