Secure usage of public key certificates relies on the possibility to revoke such a certificate in certain situations, for example in case its corresponding private key is compromised. The usual approach for providing revocation information is based on Certificate Revocation Lists (CRLs). CRLs need to be downloaded frequently by end-users to insure the timeliness of the revocation information. I...

Good public-key infrastructures (PKIs) are essential to make electronic commerce secure. Quite recently, certificate verification trees (CVTs) have been introduced as a tool for implementation of large-scale certification authorities (CAs). In most aspects, the CVT approach outperforms previous approaches like X.509 and certificate revocation lists, SDSI/SPKI, certificate revocation trees, etc....

Managing public key certificates revocation has long been a central issue in public key infrastructures. Though various certificate revocation mechanisms have been proposed to address this issue, little effort has been devoted to the empirical analysis of real-world certificate revocation data. In this paper, we conduct such an empirical analysis based on a large amount of data collected from V...

We introduce a revocation model for handling personal data in cyberspace. The model is motivated by a series of workshops undertaken by the EnCoRe project aimed at understanding the control requirements of a variety of data subjects. We observe that there is a lack of understanding of the various technical options available for implementing revocation preferences, and introduce the concept of i...

Enhanced Privacy ID (EPID) is a cryptographic scheme that enables the remote authentication of a hardware device while preserving the privacy of the device. EPID can be seen as a direct anonymous attestation scheme with enhanced revocation capabilities. In EPID, a device can be revoked if the private key embedded in the hardware device has been extracted and published widely so that the revocat...

There are few studies on how social workers deal with cases regarding transnational surrogacy. Our study intends to contribute to filling this gap. In Sweden, surrogacy as an assisted reproductive technology method is not permitted. As a result, many prospective parents have turned abroad, mainly to India, for surrogacy. There are no laws regulating surrogacy in Sweden, and difficulties have ar...

There are several problems associated with the current ways that certificates are published and revoked. This paper discusses these problems, and then proposes a solution based on the use of WebDAV, an enhancement to the HTTP protocol. The proposed solution provides instant certificate revocation, minimizes the processing costs of the certificate issuer and relying party, and eases the administ...

Public Key Infrastructure is a key infrastructure for secure and trusted communication on the Internet. This paper revisits the problem of providing timely certificate revocation focusing on the needs of mobile devices. We survey existing schemes then present a new approach where the principal’s server functions as the directory for its own revocation information. We evaluate the properties and...

BACKGROUND A trial-level surrogate end point for a randomized clinical trial may allow assessment of the relative benefits of the treatment to be performed at an earlier time point and potentially with a smaller sample size. However, determining whether an end point is a reliable trial-level surrogate based on results of previous trials is not straightforward. The question of trial-level surrog...

The perinatal outcome of pregnancies (both single and multiple) established after in-vitro fertilization (IVF)-surrogacy was evaluated and compared to the outcome of pregnancies that resulted from standard IVF. Analysis of medical records and a telephone interview with physicians, IVF-surrogates, and commissioning mothers were conducted to assess prenatal follow up and delivery care in several ...