Route 66: Passively Breaking All GSM Channels

Philip S. Vejre, Andrey Bogdanov

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review


The A5/2 stream cipher used for encryption in the GSM mobile phone standard has previously been shown to have serious weaknesses. Due to a lack of key separation and flaws in the security protocols, these vulnerabilities can also compromise the stronger GSM ciphers A5/1 and A5/3. Despite GSM's huge impact in the field, only a small selection of its channels have been analyzed. In this paper, we perform a complete practical-complexity, ciphertext-only cryptanalysis of all 66 encoded GSM channels. Moreover, we present a new passive attack which recovers the encryption key by exploiting the location updating procedure of the GSM protocol. This update is performed automatically even when the phone is not actively used. Interestingly, the attack potentially enables eavesdropping of future calls.
Original languageEnglish
Title of host publicationInformation Security and Privacy : 19th Australasian Conference, ACISP 2014. Proceedings
Publication date2014
ISBN (Print)978-3-319-08343-8
ISBN (Electronic)978-3-319-08344-5
Publication statusPublished - 2014
Event19th Australasian Conference on Information Security and Privacy - Wollongong, Australia
Duration: 7 Jul 20149 Jul 2014
Conference number: 19


Conference19th Australasian Conference on Information Security and Privacy
SeriesLecture Notes in Computer Science

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