Public-key cryptography is widely used to secure transactions among distributed systems and the Public Key Infrastructure (PKI) is the infrastructure that allows to securely deliver the public keys to these systems. The public key delivery is usually performed by way of a digital document called certificate. Digital certificates have a limited life-time and the revocation is the mechanism under...

This paper proposes a “mechanism-based PKI”, in which only a mechanism for generating user's private keys is installed on a smart card. The private key is generated inside the smart card at the event that the legitimate user gives a “seed of private key” to his/her smart card in order to sign a massage. The key exists nowhere except while users are signing a massage. Thus, users no longer need ...

The classical certificate systems are computationally inefficient, since they use signature operations based on public key cryptosystems. The nested certificates (A. Levi, Design and performance evaluation of the nested certification scheme and its applications in public key infrastructures, Ph.D. Thesis, Department of Computer Engineering, Boğaziçi University, Istanbul, Turkey) are proposed to...

Public health surveillance is the cornerstone of public health practice. The uses of surveillance include the identification of patterns of health among population subgroups. The assessment of race and ethnicity in public health surveillance is fundamental to the reduction of preventable excesses in poor health among racial and ethnic populations. We review the use of race and ethnic variables ...

We analyze the notion of “local names” in SPKI/SDSI. By interpreting local names as distributed groups, we develop a simple logic program for SPKI/SDSI’s linked localname scheme and prove that it is equivalent to the nameresolution procedure in SDSI 1.1 and the 4-tuple-reduction mechanism in SPKI/SDSI 2.0. This logic program is itself a logic for understanding SDSI’s linked local-name scheme an...

Public key infrastructure has been proposed as a promising foundation for verifying the authenticity of communicating parties and transferring trust over the internet. One of the key issues in public key infrastructure is how to manage certificate revocations. Various technical solutions dealing with key revocation have been proposed. However, to the best of our best knowledge, no rigorous effo...

The Public Key Infrastructure(PKI) provides facilities for data encryption, digital signature and time stamping. It is a system where different authorities verify and authenticate the validity of each participant with the use of digital certificates. A Certificate Policy (CP) is a named set of rules and it indicates the applicability of a certificate in a Public Key Infrastructure. Sometimes tw...

SPKI/SDSI is a proposed public key infrastructure standard that incorporates the SDSI public key infrastructure. SDSI’s key innovation was the use of local names. We previously introduced a Logic of Local Name Containment that has a clear semantics and was shown to completely characterize SDSI name resolution. Here we show how our earlier approach can be extended to deal with a number of key fe...

Nested certification is a methodology for efficient certificate path verification. Nested certificates can be used together with classical certificates in the Public Key Infrastructures (PKIs). Such a PKI, which is called Nested certificate based PKI (NPKI), is proposed in this paper as alternative to classical PKI. The NPKI formation model is a transition from an existing PKI by issuing nested...

current article is allocated to the report of a research in which the income elasticities of urban families” demand for public education in time period of 2008-2013 were estimated separately according to the income deciles and by applying rotterdam demand system, it was clarified that public education is normal commodity. different size of estimative elasticities indicated that public education...