## CryptoDB

### Keith M. Martin

#### Publications

Year
Venue
Title
2015
EPRINT
2015
EPRINT
2014
EPRINT
2009
EPRINT
We consider symmetric key predistribution in grid-based wireless sensor networks. Networks consisting of wireless sensor nodes arranged in a grid pattern have many useful applications, including environmental monitoring and agribusiness. The structured physical distribution of nodes in such networks facilitates efficient distribution of keys to the nodes prior to deployment. It has been shown that combinatorial objects known as distinct-difference configurations (DDCs) can be used to construct effective key predistribution schemes (KPSs) for grid-based networks. In this paper we observe that the regular topology of a grid-based network enables an efficient trade-off between the connectivity, resilience and storage requirements of a KPS, and we discuss the balancing of these properties to suit application requirements. We then show how recent results on the construction of DDCs can be used to produce KPSs that achieve the desired balance, and we provide explicit algorithms for the instantiation of these schemes.
2004
EPRINT
Threshold schemes allow secret data to be protected amongst a set of participants in such a way that only a pre-specified threshold of participants can reconstruct the secret from private information (shares) distributed to them on system setup using secure channels. We consider the general problem of designing unconditionally secure threshold schemes whose defining parameters (the threshold and the number of participants) can later be changed by using only public channel broadcast messages. In this paper we are interested in the efficiency of such threshold schemes, and seek to minimise storage costs (size of shares) as well as optimise performance in low bandwidth environments by minimising the size of necessary broadcast messages. We prove a number of lower bounds on the smallest size of broadcast message necessary to make general changes to the parameters of a threshold scheme in which each participant already holds shares of minimal size. We establish the tightness of these bounds by demonstrating optimal schemes.
2004
EPRINT
We consider the problem of changing the parameters of an established ideal $(k,n)$-threshold scheme without the use of secure channels. We identify the parameters $(k',n')$ to which such a scheme can be updated by means of a broadcast message and then prove a lower bound on the size of the relevant broadcast. The tightness of this bound is demonstrated by describing an optimal procedure for updating the parameters of an ideal scheme.
2003
EPRINT
In threshold cryptography the goal is to distribute the computation of basic cryptographic primitives across a number of nodes in order to relax trust assumptions on individual nodes, as well as to introduce a level of fault-tolerance against node compromise. Most threshold cryptography has previously looked at the distribution of public key primitives, particularly threshold signatures and threshold decryption mechanisms. In this paper we look at the application of threshold cryptography to symmetric primitives, and in particular the encryption or decryption of a symmetric key block cipher. We comment on some previous work in this area and then propose a model for shared encryption / decryption of a block cipher. We will present several approaches to enable such systems and will compare them.
1997
JOFC
1996
JOFC
1995
EUROCRYPT
1994
ASIACRYPT
1993
CRYPTO
1992
AUSCRYPT
1990
AUSCRYPT

Asiacrypt 2009
Asiacrypt 2008
Eurocrypt 2002
Asiacrypt 2002