4 ms·

The paper looks suspicious to me. - Novel crypto analysis technique which can't be revealed because "a lot of work to be done to obtain an optimized, more effi

by dchest 7y ago

The paper looks suspicious to me. - Novel crypto analysis technique which can't be revealed because "a lot of work to be done to obtain an optimized, more efficient and industry-level version". - Claim that success probability is low, but "we have a 2nd algorithm": "To date the probability of success is still very low (p = 0.025) but we are optimistic about the possibility of significantly increasing it in the upcoming months. Indeed we have a second algorithm, which is theoretically proven, with a success rate of 0.25. It is not yet fully tested and executed because it requires a higher computing power, although it is still reasonable for operational cryptanalysis (which can be repeated over time)." - Claim that SIMON algorithm had been introduced in the Linux 4.16 kernel (it was Speck, not Simon). May be an honest typo. - Testing on Odroid cluster. - Can't find anything on "Alba3 Group" or the authors (who have @protonmail.com address -- also suspicious). - "The only reference for this magnitude of cryptanalysis is [9]. In 2002, a 64-bit RC4 key was obtained in 1,754 days (300,000 participants). Today, to keep up with the evolution of computing power since 2002, it is necessary to divide by 2^10, or about 3 days with the same number of participants." It was RC5, not RC4 (it's even in the title of reference -- again, may be a typo), and how did they come up with 2^10 number? I don't math, but it also looks suspicious: https://twitter.com/colmmacc/status/1127100892883312640 https://twitter.com/colmmacc/status/1127100892883312640 See also: https://www.reddit.com/r/crypto/comments/bn5hds/crikey_key_recovery_attack_on_simon_3264/en37dh0/ https://www.reddit.com/r/crypto/comments/bn5hds/crikey_key_r...

wwwigham 7y ago
The math isn't too suspicious from what I can read, though I'm by no means an expert - it's just set stuff, from what I can tell. I think that Twitter post is just confusing the different fonts for the sets vs the scalars. "The cardinality of the set of keys is equal to two to the power of the length of the key" is a pretty sensible statement. The Yi is probably a typo, considering the `Xi = Xi` on the prior line is a bit redundant (and this is preprint, so I'd forgive it). In any case, my real takeaway: > Our main result is that we can find a 64-bit key in about three days (average time) on two Odroid MC1 clusters (8 Gb) [18] from two pairs of plaintext/ciphertext. The algorithm isn't strong vs key reuse. I'm unsure if it actually claimed to be so - key reuse is almost always a big problem, though, and in this case they're exploiting the birthday paradox to make the search for the key more efficient.
Merovius 7y ago
Just as the only thing I can add: > how did they come up with 2^10 number? I'd guess common interpretation of Moore's law as a doubling of computing power every 18 months. 2002 was 17y ago, so you end up with ~11 doublings. Discrepancy can be explained by ballparking.

by dchest 7y ago

wwwigham 7y ago

The math isn't too suspicious from what I can read, though I'm by no means an expert - it's just set stuff, from what I can tell. I think that Twitter post is just confusing the different fonts for the sets vs the scalars. "The cardinality of the set of keys is equal to two to the power of the length of the key" is a pretty sensible statement. The Yi is probably a typo, considering the `Xi = Xi` on the prior line is a bit redundant (and this is preprint, so I'd forgive it). In any case, my real takeaway: > Our main result is that we can find a 64-bit key in about three days (average time) on two Odroid MC1 clusters (8 Gb) [18] from two pairs of plaintext/ciphertext. The algorithm isn't strong vs key reuse. I'm unsure if it actually claimed to be so - key reuse is almost always a big problem, though, and in this case they're exploiting the birthday paradox to make the search for the key more efficient.

Merovius 7y ago

Just as the only thing I can add: > how did they come up with 2^10 number? I'd guess common interpretation of Moore's law as a doubling of computing power every 18 months. 2002 was 17y ago, so you end up with ~11 doublings. Discrepancy can be explained by ballparking.