Digital certificates and threshold cryptography

This dissertation discusses the use of secret sharing cryptographic protocols for distributing and sharing of secret documents, in our case PDF documents. We discuss the advantages and uses of such a system in the context of collaborative environments. Description of the cryptographic protocol involved and the necessary Public Key Infrastructure (PKI) shall be presented. We also provide an implementation of this framework as a “proof of concept” and fundament the use of a certificate extension as the basis for threshold cryptography. Details of the shared secret distribution protocol and shared secret recovery protocol shall be given as well as the associated technical implementation details. The actual secret sharing algorithm implemented at this stage is based on an existing well known secret sharing scheme that uses polynomial interpolation over a finite field. Finally we conclude with a practical assessment of our prototype

A New Strong Proactive Verifiable Secret Sharing Scheme with Unconditional Security

Title from PDF of title page, viewed on January 20, 2011.Thesis advisor: Lein Harn.Vita.Thesis (M.S.)--School of Computing and Engineering. University of Missouri--Kansas City, 2010.Includes bibliographic references (pages 55-58).In secret sharing scheme, the master secret and all the private shares (which are distributed by the dealer to the shareholders) are the two secrets which are to be maintained confidentially. In all the secret sharing schemes proposed till date, private shares are reused to reconstruct the master secret. But we proposed a new way of Proactive Secret Sharing Scheme in which, instead of renewing the private shares frequently at the beginning of each timeslot during the share renewal process, each time master secret is renewed. In this way private shares can be reused for a longer period of time and to construct different master secrets. In addition, after each renewing process, shareholders can work together to verify that their private shares are consistent without revealing private shares. We also proposed protocols to generate and renew master secret, authenticate public shares of the master secret, add or revoke shares and change threshold of the master secret. Thus an enhancement to Proactive Secret Sharing is proposed in this thesis and this unique feature simples the implementation of PSS as the change is to be made only to the master secret (central server) without effecting all private shares.Introduction -- Related Work -- Our Scheme -- Conclusion

Secret sharing using artificial neural network

Secret sharing is a fundamental notion for secure cryptographic design. In a secret sharing scheme, a set of participants shares a secret among them such that only pre-specified subsets of these shares can get together to recover the secret. This dissertation introduces a neural network approach to solve the problem of secret sharing for any given access structure. Other approaches have been used to solve this problem. However, the yet known approaches result in exponential increase in the amount of data that every participant need to keep. This amount is measured by the secret sharing scheme information rate. This work is intended to solve the problem with better information rate

Secret Sharing Schemes with Veto Capabilities

A secret sharing scheme permits a secret to be shared among participants in such a way that only qualified subsets of participants can recover the secret, but any non-qualified subset has absolutely no information on the secret. In this paper we consider the problem of designing efficient secret sharing schemes having the additional feature that qualified minorities can forbid any other set of participants from reconstructing the secret key