# Tag Info

1

I'm not aware of any case where somebody actually searched for such a collision. However it would certainly be possible as the same workload ($2^{64}$) was already accomplished a few years ago (2002) by this project, having brute-forced RC5-64. Now assume you'd use the full power of the bitcoin blockchain (300 Peta-Hashes / s = 600 Peta-Hashes /s for ...

1

From what you say, I assume that you are talking about the Crypto 3 challenge from HackingWeek. As Ruggero explained, the curve is vulnerable to both the MOV attack and the older FR attack that works similarily, using Weil or Tate pairings (respectivly). A simple sage code for the FR-attack would be: q = 134747661567386867366256408824228742802669457 Zq = ...

3

In your particular case the order of the point divides $p-1$, this means that the embedding degree of your curve is 1. You should be able to apply the MOV attack to transfer your instance of ECDLP into an instance of DLP over $\mathbb{F}_{p}^*$. This would allow you to use the Index Calculus to solve your problem. As the Index Calculus is subexponential, ...

1

Online attacks involve an online entity - an entity that is available in real time to be used by an attacker. So if you attack a network service then you perform an online attack. Offline attacks are attacks that can be performed without such an entity, e.g. when an attacker has access to an encrypted file. Online entities can perform additional security ...

0

In the context of algorithms, the terms online sometimes refers to working on a stream of the input data. To be more precisely: the whole data set is unknown at the time the algorithm starts. So your algorithm has to take decisions that might be wrong. Heuristics and approximation are part of these. Offline algorithms instead work on the full data set, that ...

5

An offline attack require work from the attacker only (or mostly), with no (or little) communication with the system (e.g. server) under attack (holding the key). An online attack requires (typically significant) work of the system under attack (including communication). The computing power or communication bandwidth of the system under attack is typically ...

1

I don't think anyone has addressed the time issue. According to the Margolus-Levitin theorem the limit on the number of operations per second is $6\times10^{33}$ per Joule. The Sun's energy output is about $3.83\times10^{26}$J/sec. You would need to save up the energy output of the Sun for about 25 years to be able to then do $2^{255}$ operations in one ...

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