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...

In the recent past, a lot of work has been done in establishing public key infrastructures (PKIs) for electronic commerce (e-commerce) applications. Unfortunately, most of these PKIs can only be used to authenticate the participants of e-commerce applications; they can't be used to properly authorize the participants and to control access to system resources accordingly. Consequently, these PKI...

With this construction we show that MD5 collisions can be crafted easily in such a way that the principles underlying the trust in Public Key Infrastructure are violated. In particular we find it worrying that from one certificate alone it cannot be determined whether another, different certificate may exist with the same signature. For the second certificate the issuing Certification Authority...

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...

Nested certificates are used to certify their subject certificates. In this way, the subject certificates can be verified via their nested certificates without using signature verification methods based on public key cryptosystems. Such a verification method is called as subject certificate verification. In this paper, subject certificate verification method will be introduced. It will be shown...

Simulation-based security notions for cryptographic protocols are regarded as highly desirable, primarily because they admit strong composability and, consequently, a modular design. In this paper, we give a simulation-based security definition for two-round authenticated message exchange and show that a concrete protocol, 2AMEX-1, satisfies our security property, that is, we provide an ideal f...

Much of the literature related to public key infrastructure (PKI) uses terms such as “trust” extensively and assumes that certification authorities (CAs) are trusted third parties (TTPs). It is certainly true that the best known CAs today are commercial TTPs, and such CAs have played an important role in making the general public aware of PKIs. But, not all PKIs need adopt this sort of CA model...

Advances in wireless network technology and the continuously increasing users of Personal Trusted Device (PTD) make the latter an ideal channel for offering personalized services to mobile users. In this paper, we apply some cryptology (such as public key infrastructure, hashing chain and digital signature) to propose a realistic mobile ticket system such that fairness, non-repudiation, anonymi...

It is generally accepted that data encryption is the key role in current and future technologies. Many Public key cryptography schemes were presented, divided into different classes depending on a specific mathematical problem. Cryptography plays an important task in accomplishing information security. It is used for encrypting or signing data at the source before transmission, and then decrypt...

In this paper we propose a new approach to privately compute the set-union cardinality and the set-intersection cardinality among multiple honest-but-curious parties. Our approach is inspired by a proposal of Ashok and Mukkamala (DBSec’14) which deploys Bloom filters to approximate the size tightly. One advantage of their solution is that it avoids ample public-key cryptography. Unfortunately, ...