A New Guess-and-Determine Method for Cryptanalysis of the GSM Encryption

Table 3

Comparison of related attacks (PW: precomputation workload; CC: computational complexity).

Attack	PW	CC	Known keystream	Success probability (%)	Memory requirement	Time to recover key
Proposed in [12]			2^20.8 bits	63	64 GB	Impractical attack
Biased birthday attack 1 [14]		1 second	bits	60	146 GB	Impractical attack
Biased birthday attack 2 [14]		1 second	bits	60	292 GB	Impractical attack
Subgraph attack [14]		3–6 minutes	bits	60	146 GB	Impractical attack
Proposed in [15]	0	2^51.24	Only 64 bits	18	0	7 hours
Proposed in [20]	0	2^54.04	Only 64 bits	100	0	7 hours
Proposed in [4]	NA	NA	Only 64 bits	81	984 GB	9 seconds
Proposed in [5]	NA	NA	Only 64 bits	80.08	3.84 TB	33 seconds
Proposed in this paper	0	2^52	Only 64 bits	96.6	64 GB	12 seconds

Large amount of keystream requirements makes first four attacks impractical; needing of lot of precomputation data is also a big obstacle in practicality of these four attacks.