Compression is desirable for network applications as it saves bandwidth; however, when data is compressed before being encrypted, the amount of compression leaks information about the amount of redundancy in the plaintext. This side channel has led to successful CRIME and BREACH attacks on web traffic protected by the Transport Layer Security (TLS) protocol. The general guidance in light of these attacks has been to disable compression, preserving confidentiality but sacrificing bandwidth. In this paper, we examine two techniques---heuristic separation of secrets and fixed-dictionary compression---for enabling compression while protecting high-value secrets, such as cookies, from attack. We model the security offered by these techniques and report on the amount of compressibility that they can achieve.
Joint work with Janaka Alawatugoda (QUT) and Colin Boyd (NTNU).
Dr Douglas Stebila is a Senior Lecturer in cryptography at the Queensland University of Technology in Brisbane, Australia. His research focuses on improving the security of Internet cryptography protocols such as SSL/TLS and SSH. His previous work on the integration and standardization of elliptic curve cryptography in SSL/TLS has been deployed on hundreds of millions of web browsers and servers worldwide. He holds an MSc from the University of Oxford and a PhD from the University of Waterloo.
Last modified: Tuesday, 24-Nov-2015 10:07:14 NZDT
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