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Software Seminar Series (S3)

Platon Kotzias

Wednesday, October 17, 2018

10:45am Meeting room 302 (Mountain View), level 3

Platon Kotzias, PhD Student, Instituto IMDEA Software

Coming of Age: A Longitudinal Study of TLS Deployment

Abstract:

The Transport Layer Security (TLS) protocol is the de-facto standard for encrypted communication on the Internet. However, it has been plagued by a number of different attacks and security issues over the last years. Addressing these attacks requires changes to the protocol, to server- or client-software, or to all of them. In this paper we conduct the first large-scale longitudinal study examining the evolution of the TLS ecosystem over the last six years. We place a special focus on the ecosystem's evolution in response to high-profile attacks. For our analysis, we use a passive measurement dataset with more than 319.3B connections since February 2012, and an active dataset that contains TLS and SSL scans of the entire IPv4 address space since August 2015. To identify the evolution of specific clients we also create the-to our knowledge-largest TLS client fingerprint database to date, consisting of 1,684 fingerprints. We observe that the ecosystem has shifted significantly since 2012, with major changes in which cipher suites and TLS extensions are offered by clients and accepted by servers having taken place. Where possible, we correlate these with the timing of specific attacks on TLS. At the same time, our results show that while clients, especially browsers, are quick to adopt new algorithms, they are also slow to drop support for older ones. We also encounter significant amounts of client software that probably unwittingly offer unsafe ciphers. We discuss these findings in the context of long tail effects in the TLS ecosystem.


Time and place:
10:45am Meeting room 302 (Mountain View), level 3
IMDEA Software Institute, Campus de Montegancedo
28223-Pozuelo de Alarcón, Madrid, Spain


Anais Querol

Tuesday, October 09, 2018

10:45am Meeting room 302 (Mountain View), level 3

Anais Querol, PhD Student, Instituto IMDEA Software

Conditional Differential Cryptanalysis of the ARX Symmetric Primitive Salsa20

Abstract:

Symmetric key cryptography is an essential part of communication systems, where a secret key is used to protect data confidentiality. Surprisingly, the only way of trusting these ciphers is to perform continuous analysis that update the security margin. With the advent of quantum computers in an arguably near future, the security of nowadays ciphers has been put into question. While most currently used asymmetric primitives would be completely broken, doubling the key size of symmetric constructions provides the same level of security with respect to exhaustive key search. However, we still have a long way to go in the field of quantum cryptography and further cryptanalysis must be carried out to reassure the validity of these emerging ciphers. We have studied the Salsa20 family of ciphers, which has received very little cryptanalysis ever since the most relevant result one decade ago despite the inclusion of this cipher suit in TLS 1.3. During this talk, I will explain a new attack to 8 rounds of Salsa using conditional differential cryptanalysis, which comprises the main result of my Master internship. This work has taken place at Inria Paris in the context of the ERC project QUASYModo under the supervision of the researcher María Naya Plasencia.


Time and place:
10:45am Meeting room 302 (Mountain View), level 3
IMDEA Software Institute, Campus de Montegancedo
28223-Pozuelo de Alarcón, Madrid, Spain


Software Seminar Series (S3) - Primavera 2018