Initialisation flaws in the A5-GMR-1 satphone encryption algorithm
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Accepted Version
(PDF 292kB)
A5GMR1_Init_AISC16_vFinal.pdf. |
Description
A5-GMR-1 is a synchronous stream cipher used to provide confidentiality for communications between satellite phones and satellites. The keystream generator may be considered as a finite state machine, with an internal state of 81 bits. The design is based on four linear feedback shift registers, three of which are irregularly clocked. The keystream generator takes a 64-bit secret key and 19-bit frame number as inputs, and produces an output keystream of length between $2^8$ and $2^{10}$ bits. Analysis of the initialisation process for the keystream generator reveals serious flaws which significantly reduce the number of distinct keystreams that the generator can produce. Multiple (key, frame number) pairs produce the same keystream, and the relationship between the various pairs is easy to determine. Additionally, many of the keystream sequences produced are phase shifted versions of each other, for very small phase shifts. These features increase the effectiveness of generic time-memory tradeoff attacks on the cipher, making such attacks feasible.
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ID Code: | 211591 | ||
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Item Type: | Chapter in Book, Report or Conference volume (Conference contribution) | ||
ORCID iD: |
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Measurements or Duration: | 7 pages | ||
Keywords: | Cryptanalysis, Initialisation, Satellite phones, Stream ciphers, Time-memory attacks | ||
DOI: | 10.1145/2843043.2843357 | ||
ISBN: | 978-1-4503-4042-7 | ||
Pure ID: | 32977607 | ||
Divisions: | Past > Institutes > Institute for Future Environments Past > QUT Faculties & Divisions > Science & Engineering Faculty Current > Schools > School of Mathematical Sciences |
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Copyright Owner: | Consult author(s) regarding copyright matters | ||
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Deposited On: | 07 Jul 2021 04:06 | ||
Last Modified: | 20 Jul 2024 19:24 |
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