Changes between Version 5 and Version 6 of HadoopA51


Ignore:
Timestamp:
Jan 19, 2010, 1:13:04 AM (14 years ago)
Author:
lgrijincu
Comment:

--

Legend:

Unmodified
Added
Removed
Modified
  • HadoopA51

    v5 v6  
    88
    99== History & Motivation ==
     10
     11=== History ===
    1012A5/1 is one of the most prolific stream ciphers used worldwide (surpassing the one used in ssh or https by total size of encrypted data per year). It is used to provide OTA communication privacy and authentification in the GSM cell phone networks between a cell phone and the first cell tower.
    1113
    1214Though at first the algorithm was not public, it was made available by researchers through reverse engineering and hardware monitoring. A reference implementation is given in https://svn-batch.grid.pub.ro/svn/PP2009/proiecte/HadoopA51/docs/a5/a5-1.c
    1315
     16Through time the algorithm was proven weak & broken (a selection of proofs):
     17 * 1997 - Jovan Golic published "Cryptanalysis of Alleged A5 Stream Cipher" (http://jya.com/a5-hack.htm). Their attach uses a time-memory trade-off attack (based on the birthday paradox) which reveals an unknown internal state at a known time for a known keystream sequence. This internal state is then used to obtain the secret key.
     18 * 2000 - Eli Biham and Orr Dunkelman analize A5/1 in "Cryptanalysis of the A5/1 GSM Stream Cipher" demonstrate an attack on A5/1 which relies on ~2^20 known plaintext data.
     19 * 2003 - Barkan et al. published several active attacks on GSM by forcing a phone to use A5/2 (which is weaker than A5/1). As the key used in A5/2 and A5/1 in GSM implementations is the same, this lead to breaking the A5/1 code.
     20 * 2005 - The same authors in "Conditional Estimators: An Effective Attack on A5/1" provide yet another attack on A5/1.
     21 * 2009 - Karsten Nohl and Chris Paget provide details of an rainbow table attack on A5/1 in "GSM: SRSLY?" at the 26th Chaos Communication Congress (26C3). This attack was announched in September 2009 and lead to this project (HadoopA51)
    1422
    1523