Challenge "CMEA 2"  

  By: admin on Dec. 6, 2010, 8:24 p.m.

CMEA is a block cipher and was one of the 4 cryptographic primitives of the mobile communications network in the US. It is your challenge to perform a known-plaintext attack on CMEA with 40 known plaintext blocks given.

 Last edited by: admin on Oct. 31, 2021, 2:54 a.m., edited 1 time in total.

Re: Challenge  

  By: D3d4lu5 on July 26, 2017, 4:56 p.m.

Do I need special computational power to solve this challenge?

My program works quite well for "CMEA 1" and finds the key in a few minutes.

But for this challenge it can not rule out a single putative T(0) in the primary phase and also not a single (K6,K7)-pair for most of the 164 putative T(0) in the backtracking step.

Also the average number of possible T(j) to test for each T(0) in the meet-in-the-middle is about 40000.

Are there better results for the primary phase and the backtracking or do I need to buy a faster computer? [HTML_REMOVED]

Re: Challenge  

  By: AnLeRo on Aug. 2, 2017, 5:26 p.m.

I did not solve the challenge myself, but in general you need more computational power for level III challenges than for level II.

Re: Challenge  

  By: madness on April 29, 2021, 1:37 p.m.

I doubt that I will get any useful info on the forum, but I seem to have eliminated all possibilities for T[0].

Re: Challenge  

  By: be on April 30, 2021, 11:11 a.m.

I seem to have eliminated all possibilities for T[0].

Please send me a private email and explain a bit more what you want to know. If I can't help, I'll bring you in contact with the author of the challenge. Best regards, BE

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