This document defines a practical architecture and protocols for offering privacy for a user who requests and uses an X.509 certificate containing a pseudonym, while still retaining the ability to map such a certificate to the real user who requested it. The architecture is compatible with IETF certificate request formats such as PKCS10 (RFC 2986) and CMC (RFC 5272). The architecture separates ...

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...

Signcryption is a useful cryptographic primitive that achieves confidentiality and authentication in an efficient manner. As an extension of signcryption in certificate-based cryptography, certificate-based signcryption preserves the merits of certificate-based cryptography and signcryption simultaneously. In this paper, we present an improved security model of certificate-based signcryption th...

For the last decade, perhaps the most commonly used type of end-user security has been the HTTP Secure (HTTPS) protocol employed by web browsers (which runs over the Secure Sockets Layer, SSL or its successor, TLS). In HTTPS, any service (such as a website) may create its own cryptographic certificate to secure its communication channel, and clients use this certificate to verify data from, and...

We give the first linear-time certifying algorithms to recognize trivially perfect graphs, with sublinear certificates for negative output. In case of membership in the class of trivially perfect graphs, our algorithms provide as certificate a structure for the input graph that characterizes the class, and in case of non-membership they provide as certificate a forbidden induced subgraph of the...

Program verification techniques based on programming logics and verification condition generators provide a powerful means to reason about programs. Whereas these techniques have very often been employed in the context of high-level languages in order to benefit from their structural nature, it is often required, especially in the context of mobile code, to prove the correctness of compiled pro...