DSTC: DNS-based Strict TLS Configurations

Most TLS clients such as modern web browsers enforce coarse-grained TLS security configurations. They support legacy versions of the protocol that have known design weaknesses, and weak ciphersuites that provide fewer security guarantees (e.g. non Forward-Secrecy), mainly to provide backward compatibility. This opens doors to downgrade attacks, as is the case of the POODLE attack [18], which exploits the client's silent fallback to downgrade the protocol version to exploit the legacy version's flaws. To achieve a better balance between security and backward compatibility, we propose a DNS-based mechanism that enables TLS servers to advertise their support for the latest version of the protocol and strong ciphersuites (that provide Forward-Secrecy and Authenticated-Encryption simultaneously). This enables clients to consider prior knowledge about the servers' TLS configurations to enforce a fine-grained TLS configurations policy. That is, the client enforces strict TLS configurations for connections going to the advertising servers, while enforcing default configurations for the rest of the connections. We implement and evaluate the proposed mechanism and show that it is feasible, and incurs minimal overhead. Furthermore, we conduct a TLS scan for the top 10,000 most visited websites globally, and show that most of the websites can benefit from our mechanism

Postcards from the post-HTTP world: Amplification of HTTPS vulnerabilities in the web ecosystem

HTTPS aims at securing communication over the Web by providing a cryptographic protection layer that ensures the confidentiality and integrity of communication and enables client/server authentication. However, HTTPS is based on the SSL/TLS protocol suites that have been shown to be vulnerable to various attacks in the years. This has required fixes and mitigations both in the servers and in the browsers, producing a complicated mixture of protocol versions and implementations in the wild, which makes it unclear which attacks are still effective on the modern Web and what is their import on web application security. In this paper, we present the first systematic quantitative evaluation of web application insecurity due to cryptographic vulnerabilities. We specify attack conditions against TLS using attack trees and we crawl the Alexa Top 10k to assess the import of these issues on page integrity, authentication credentials and web tracking. Our results show that the security of a consistent number of websites is severely harmed by cryptographic weaknesses that, in many cases, are due to external or related-domain hosts. This empirically, yet systematically demonstrates how a relatively limited number of exploitable HTTPS vulnerabilities are amplified by the complexity of the web ecosystem

High-level Cryptographic Abstractions

The interfaces exposed by commonly used cryptographic libraries are clumsy, complicated, and assume an understanding of cryptographic algorithms. The challenge is to design high-level abstractions that require minimum knowledge and effort to use while also allowing maximum control when needed. This paper proposes such high-level abstractions consisting of simple cryptographic primitives and full declarative configuration. These abstractions can be implemented on top of any cryptographic library in any language. We have implemented these abstractions in Python, and used them to write a wide variety of well-known security protocols, including Signal, Kerberos, and TLS. We show that programs using our abstractions are much smaller and easier to write than using low-level libraries, where size of security protocols implemented is reduced by about a third on average. We show our implementation incurs a small overhead, less than 5 microseconds for shared key operations and less than 341 microseconds (< 1%) for public key operations. We also show our abstractions are safe against main types of cryptographic misuse reported in the literature

Eesti elektrooniline ID-kaart ja selle turvaväljakutsed

Eesti elektrooniline isikutunnistust (ID-kaart) on üle 18 aasta pakkunud turvalist elektroonilist identiteeti Eesti kodanikele. Avaliku võtme krüptograafia ja kaardile talletatud privaatvõti võimaldavad ID-kaardi omanikel juurde pääseda e-teenustele, anda juriidilist jõudu omavaid digiallkirju ning elektrooniliselt hääletada. Käesolevas töös uuritakse põhjalikult Eesti ID-kaarti ning sellega seotud turvaväljakutseid. Me kirjeldame Eesti ID-kaarti ja selle ökosüsteemi, seotud osapooli ja protsesse, ID-kaardi elektroonilist baasfunktsionaalsust, seotud tehnilisi ja juriidilisi kontseptsioone ning muid seotud küsimusi. Me tutvustame kõiki kasutatud kiipkaardiplatforme ja nende abil väljastatud isikutunnistuste tüüpe. Iga platformi kohta esitame me detailse analüüsi kasutatava asümmeetrilise krüptograafia funktsionaalsusest ning kirjeldame ja analüüsime ID-kaardi kauguuendamise lahendusi. Lisaks esitame me süstemaatilise uurimuse ID-kaardiga seotud turvaintsidentidest ning muudest sarnastest probleemidest läbi aastate. Me kirjeldame probleemide tehnilist olemust, kasutatud leevendusmeetmeid ning kajastust ajakirjanduses. Käesoleva uurimustöö käigus avastati mitmeid varem teadmata olevaid turvaprobleeme ning teavitati nendest seotud osapooli. Käesolev töö põhineb avalikult kättesaadaval dokumentatsioonil, kogutud ID-kaartide sertifikaatide andmebaasil, ajakirjandusel,otsesuhtlusel seotud osapooltega ning töö autori analüüsil ja eksperimentidel.For more than 18 years, the Estonian electronic identity card (ID card) has provided a secure electronic identity for Estonian residents. The public-key cryptography and private keys stored on the card enable Estonian ID card holders to access e-services, give legally binding digital signatures and even cast an i-vote in national elections. This work provides a comprehensive study on the Estonian ID card and its security challenges. We introduce the Estonian ID card and its ecosystem by describing the involved parties and processes, the core electronic functionality of the ID card, related technical and legal concepts, and the related issues. We describe the ID card smart card chip platforms used over the years and the identity document types that have been issued using these platforms. We present a detailed analysis of the asymmetric cryptography functionality provided by each ID card platform and present a description and security analysis of the ID card remote update solutions that have been provided for each ID card platform. As yet another contribution of this work, we present a systematic study of security incidents and similar issues the Estonian ID card has experienced over the years. We describe the technical nature of the issue, mitigation measures applied and the reflections on the media. In the course of this research, several previously unknown security issues were discovered and reported to the involved parties. The research has been based on publicly available documentation, collection of ID card certificates in circulation, information reflected in media, information from the involved parties, and our own analysis and experiments performed in the field.https://www.ester.ee/record=b541416

Practical fair anonymous undeniable signatures

We present a new model for undeniable signatures: fair-anonymous undeniable signatures. This protocol can not only preserve the privacy of the signer (i.e. anonymity) but also track the illegal utilization of the valid signatures. In addition, our model prevents the trusted centre from forging a valid signature for any signer

Group theory in cryptography

This paper is a guide for the pure mathematician who would like to know more about cryptography based on group theory. The paper gives a brief overview of the subject, and provides pointers to good textbooks, key research papers and recent survey papers in the area.Comment: 25 pages References updated, and a few extra references added. Minor typographical changes. To appear in Proceedings of Groups St Andrews 2009 in Bath, U

An Overview of Cryptography (Updated Version, 3 March 2016)

There are many aspects to security and many applications, ranging from secure commerce and payments to private communications and protecting passwords. One essential aspect for secure communications is that of cryptography...While cryptography is necessary for secure communications, it is not by itself sufficient. This paper describes the first of many steps necessary for better security in any number of situations. A much shorter, edited version of this paper appears in the 1999 edition of Handbook on Local Area Networks published by Auerbach in September 1998

REISCH: incorporating lightweight and reliable algorithms into healthcare applications of WSNs

Healthcare institutions require advanced technology to collect patients' data accurately and continuously. The tradition technologies still suffer from two problems: performance and security efficiency. The existing research has serious drawbacks when using public-key mechanisms such as digital signature algorithms. In this paper, we propose Reliable and Efficient Integrity Scheme for Data Collection in HWSN (REISCH) to alleviate these problems by using secure and lightweight signature algorithms. The results of the performance analysis indicate that our scheme provides high efficiency in data integration between sensors and server (saves more than 24% of alive sensors compared to traditional algorithms). Additionally, we use Automated Validation of Internet Security Protocols and Applications (AVISPA) to validate the security procedures in our scheme. Security analysis results confirm that REISCH is safe against some well-known attacks