Abstract not found

. This paper is concerned with generalisations of Paillier's probabilistic encryption scheme from the integers modulo a square to elliptic curves over rings. Paillier himself described two public key encryption schemes based on anomalous elliptic curves over rings. It is argued that these schemes are not secure. A more natural generalisation of Paillier's scheme to elliptic curves is given.

In wireless sensor networks there is a need to securely store monitored data in a distributed way whenever it is either not 12 desired or simply not possible to transmit regional volatile information to an authorised recipient in real-time. In partic- 13 ular, for wireless sensor network applications with an asynchronous character, the wireless sensor network itself needs to 14 store the monitored data. Since nodes may disappear over time, a replicated and read-protected, but yet space- and energy- 15 e#cient, data storage is mandatory. In this work we provide and analyse an approach for a tiny Persistent Encrypted Data 16 Storage (tinyPEDS) of the environmental fingerprint for asynchronous wireless sensor networks. Even if parts of the net- 17 work are exhausted, restoring rules ensure that, with a high probability, environmental information from past is still 18 available.

In-network data aggregation is a popular technique for reducing the energy consumption tied to data transmission in a multi-hop wireless sensor network. However, data aggregation in untrusted or even hostile environments becomes problematic when end-to-end privacy between sensors and the sink is desired. In this paper we revisit and investigate the applicability of additively homomorphic public-key encryption algorithms for certain classes of wireless sensor networks. Finally, we provide recommendations for selecting the most suitable public key schemes for different topologies and wireless sensor network scenarios.

Abstract. We present an efficient construction of a private disjointness testing protocol that is secure against malicious provers and honest-but-curious (semi-honest) verifiers, without the use of random oracles. In a completely semi-honest setting, this construction implements a private intersection cardinality protocol. We formally define both private intersection cardinality and private disjointness testing protocols. We prove that our construction is secure under the subgroup decision and subgroup computation assumptions. A major advantage of our construction is that it does not require bilinear groups, random oracles, or non-interactive zero knowledge proofs. Applications of private intersection cardinality and disjointness testing protocols include privacy-preserving data mining and anonymous login systems.

Abstract. This paper examines secure two-party computation of functions which depend only on the Hamming distance of the inputs of the two parties. We present efficient protocols for computing these functions. In particular, we present protocols which are secure in the sense of full simulatability against malicious adversaries. We show different applications of this family of functions, including a protocol we call m-point-SPIR, which is an efficient variant of symmetric private information retrieval (SPIR). It can be used if the server’s database contains N entries, at most N / log N of which have individual values, and the rest are set to some default value. This variant of PIR is unique since it can be based on the existence of OT alone. 1

We propose an elliptic curve scheme over the ring Z n 2, which is efficient and semantically secure in the standard model. There appears to be no previous elliptic curve cryptosystem based on factoring that enjoys both of these properties. KMOV scheme has been used as an underlying primitive to obtain efficiency and probabilistic encryption. Semantic security of the scheme is based on a new decisional assumption, namely, the Decisional Small-x e-Multiples Assumption. Confidence on this assumption is also discussed.

Abstract—We present an overview of end-to-end encryption solutions for convergecast traffic in wireless sensor networks that support in-network processing at forwarding intermediate nodes. Other than hop-by-hop based encryption approaches, aggregator nodes can perform in-network processing on encrypted data. Since it is not required to decrypt the incoming ciphers before aggregating, substantial advantages are 1) neither keys nor plaintext is available at aggregating nodes, 2) the overall energy consumption of the backbone can be reduced, 3) the system is more flexible with respect to changing routes, and finally 4) the overall system security increases. We provide a qualitative comparison of available approaches, point out their strengths, respectively weaknesses, and investigate opportunities for further research. Index Terms—Cryptography, wireless sensor networks, convergecast, concealed data aggregation. Ç 1

Abstract- Data aggregation in wireless sensor networks (WSN) helps eliminate information redundancy and increase the lifetime of the network. When homomorphic encryption is used for data aggregation, end-to-end encryption is achieved and aggregation function like average or minimum/maximum can be computed on the encrypted data. Aggregation functions like minimum/maximum rely on comparison operation. But, it has been shown that any homomorphic encryption is insecure against ciphertext only attacks if they support comparison operation. The order preserving encryption scheme (OPES) has been suggested for WSNs, for secure comparison of encrypted data at the aggregator node in WSNs. But, the computational cost at the sensor nodes in WSNs by using OPES is huge. This paper provides an alternative for OPES when used to calculate aggregation function minimum/maximum. In this paper we briefly describe some homomorphic encryption schemes and show how the sensed data is encrypted by using these homomorphic encryption schemes. we show how aggregation function minimum/maximum can be computed at the aggregator node in WSNs by performing addition operation and not comparison operation on the data encrypted with homomorphic encryption schemes. We also show how our scheme helps eliminate the encryption cost at the sensor node in WSNs. Index Terms—Wireless sensor networks, data encryption, data aggregation, homomorphic encryption schemes. 1

In this paper we discuss algorithms that allow the concealed data aggregation (CDA) in wireless sensor networks. We describe and evaluate three algorithms that were reported to suit to the WSN scenario. As result of the evaluation, where we emphasize the awareness to potential attack scenarios, we present a brief overview of strengths and weaknesses of the algorithms. Since no algorithm provides all desirable goals, we propose two approaches to cope with the problems. The first is the successive combination of two algorithms. It increases security, while the additional efforts can be minimized by carefully selected parameters. For the second approach we face specific weaknesses and engineer mechanisms that solve the particular issues. With the considered homomorphic message authentication code and a discussion of the id-issue we exemplary evaluate the two biggest issues of the very promising CMT algorithm.