Multi-ciphersuite security of the Secure Shell (SSH) protocol

Bergsma, Florian, Dowling, Benjamin, Kohlar, Florian, Schwenk, Jörg, & Stebila, Douglas (2014) Multi-ciphersuite security of the Secure Shell (SSH) protocol. In Proceedings of the 2014 ACM SIGSAC Conference on Computer and Communications Security, ACM, Scottsdale, Arizona, pp. 369-381.

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Abstract

The Secure Shell (SSH) protocol is widely used to provide secure remote access to servers, making it among the most important security protocols on the Internet. We show that the signed-Diffie--Hellman SSH ciphersuites of the SSH protocol are secure: each is a secure authenticated and confidential channel establishment (ACCE) protocol, the same security definition now used to describe the security of Transport Layer Security (TLS) ciphersuites. While the ACCE definition suffices to describe the security of individual ciphersuites, it does not cover the case where parties use the same long-term key with many different ciphersuites: it is common in practice for the server to use the same signing key with both finite field and elliptic curve Diffie--Hellman, for example. While TLS is vulnerable to attack in this case, we show that SSH is secure even when the same signing key is used across multiple ciphersuites. We introduce a new generic multi-ciphersuite composition framework to achieve this result in a black-box way.

Impact and interest:

3 citations in Scopus
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ID Code: 78683
Item Type: Conference Paper
Refereed: Yes
Additional URLs:
Keywords: Secure Shell (SSH), key agility, cross-protocol security, multi-ciphersuite, authenticated and confidential channel establishment
DOI: 10.1145/2660267.2660286
ISBN: 9781450329576
Subjects: Australian and New Zealand Standard Research Classification > INFORMATION AND COMPUTING SCIENCES (080000) > COMPUTER SOFTWARE (080300) > Computer System Security (080303)
Australian and New Zealand Standard Research Classification > INFORMATION AND COMPUTING SCIENCES (080000) > DATA FORMAT (080400) > Data Encryption (080402)
Divisions: Current > Schools > School of Electrical Engineering & Computer Science
Current > Institutes > Institute for Future Environments
Current > QUT Faculties and Divisions > Science & Engineering Faculty
Funding:
Copyright Owner: Copyright 2014 ACM
Deposited On: 17 Nov 2014 00:35
Last Modified: 13 Nov 2016 06:56

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