Laurent Chuat

Efficient gossip protocols for verifying the consistency of Certificate logs

The level of trust accorded to certification authorities has been decreasing over the last few years as several cases of misbehavior and compromise have been observed. Log-based approaches, such as Certificate Transparency, ensure that fraudulent TLS certificates become publicly visible. However, a key element that log-based approaches still lack is a way for clients to verify that the log behaves in a consistent and honest manner. This task is challenging due to privacy, efficiency, and deployability reasons. In this paper, we propose the first (to the best of our knowledge) gossip protocols that enable the detection of log inconsistencies. We analyze these protocols and present the results of a simulation based on real Internet traffic traces. We also give a deployment plan, discuss technical issues, and present an implementation.

PKI Safety Net (PKISN): Addressing the Too-Big-to-Be-Revoked Problem of the TLS Ecosystem

In a public-key infrastructure (PKI), clients must have an efficient and secure way to determine whether a certificate was revoked (by an entity considered as legitimate to do so), while preserving user privacy. A few certification authorities (CAs) are currently responsible for the issuance of the large majority of TLS certificates. These certificates are considered valid only if the certificate of the issuing CA is also valid. The certificates of these important CAs are effectively too big to be revoked, as revoking them would result in massive collateral damage. To solve this problem, we redesign the current revocation system with a novel approach that we call PKI Safety Net (PKISN), which uses publicly accessible logs to store certificates (in the spirit of Certificate Transparency) and revocations. The proposed system extends existing mechanisms, which enables simple deployment. Moreover, we present a complete implementation and evaluation of our scheme.

The SCION internet architecture

Adhering to the end-to-end principle even more than the current Internet yields highly available point-to-point communication.

RITM: Revocation in the Middle

Although TLS is used on a daily basis by many critical applications, the public-key infrastructure that it relies on still lacks an adequate revocation mechanism. An ideal revocation mechanism should be inexpensive, efficient, secure, and privacypreserving. Moreover, rising trends in pervasive encryption pose new scalability challenges that a modern revocation system should address. In this paper, we investigate how network nodes can deliver certificate-validity information to clients. We present RITM, a framework in which middleboxes (as opposed to clients, servers, or certification authorities) store revocation-related data. RITM provides a secure revocation-checking mechanism that preserves user privacy. We also propose to take advantage of content-delivery networks (CDNs) and argue that they would constitute a fast and cost-effective way to disseminate revocations. Additionally, RITM keeps certification authorities accountable for the revocations that they have issued, and it minimizes overhead at clients and servers, as they have to neither store nor download any messages. We also describe feasible deployment models and present an evaluation of RITM to demonstrate its feasibility and benefits in a real-world deployment.

SCION: A Secure Internet Architecture

This book describes the essential components of the SCION secure Internet architecture, the first architecture designed foremost for strong security and high availability. Among its core features, SCION also provides route control, explicit trust information, multipath communication, scalable quality-of-service guarantees, and efficient forwarding. The book includes functional specifications of the network elements, communication protocols among these elements, data structures, and configuration files. In particular, the book offers a specification of a working prototype. The authors provide a comprehensive description of the main design features for achieving a secure Internet architecture. They facilitate the reader throughout, structuring the book so that the technical detail gradually increases, and supporting the text with a glossary, an index, a list of abbreviations, answers to frequently asked questions, and special highlighting for examples and for sections that explain important research, engineering, and deployment features. The book is suitable for researchers, practitioners, and graduate students who are interested in network security.

Deadline-Aware Multipath Communication: An Optimization Problem

Multipath communication not only allows improved throughput but can also be used to leverage different path characteristics to best fulfill each applications objective. In particular, certain delay-sensitive applications, such as real-time voice and video communications, can usually withstand packet loss and aim to maximize throughput while keeping latency at a reasonable level. In such a context, one hard problem is to determine along which path the data should be transmitted or retransmitted. In this paper, we formulate this problem as a linear optimization, show bounds on the performance that can be obtained in a multipath paradigm, and show that path diversity is a strong asset for improving network performance. We also discuss how these theoretical limits can be approached in practice and present simulation results.

The SCION Architecture

This chapter provides an overview of SCION. The goals to be met by a secure Internet architecture were described in the previous chapter, but to recapitulate briefly, our main aim is to design a network architecture that offers highly available and efficient point-to-point packet delivery, even if some of the network operators and devices are actively malicious. The following chapters describe the SCION architecture in increasing detail.

OPT and DRKey

This chapter presents Origin and Path Trace (OPT)—lightweight, scalable, and secure protocols for shared key setup, source authentication, and path validation. In-network source authentication and path validation are fundamental primitives for constructing higher-level security mechanisms such as DDoS mitigation, path compliance, packet attribution, or protection against flow redirection.

Isolation Domains (ISDs)

This chapter discusses SCION isolation domains in more detail. As briefly sketched in Chapter 2, an isolation domain (abbreviated as ISD to distinguish it from the common abbreviation ID) constitutes a logical clustering of the Internet’s most coarse-grained organizational unit, namely that of an autonomous system, or AS for short. An AS is a self-contained network administrated by a single entity (e.g., by an Internet service provider (ISP) or a university) and communicates with other ASes through well-defined interfaces based on contractual business relations. Figure 2.1 on Page 18 sketches how ASes are grouped into ISDs.

Configuration File Formats

This chapter describes the details of SCION configuration files. All SCION configuration files are represented in JSON [42] format.