Tagged Questions

3
votes
1answer
131 views

Using an MD5 hash as a password

Suppose Alice is using a password prompt that only accepts up to 32 characters for any particular password. Memorization of long strings of random characters is not one of Alice's strengths, so she ...
2
votes
3answers
164 views

Is it possible to work out the hash algorithm from a list of known message-hash pairs?

For example, in my situation I know hash(20) = 486e9638177faf1f34e49910491b77af. I also know the hashes for all values from 0 to 20. Is it possible to work out the ...
5
votes
0answers
58 views

MD4 First preimage - state of the art

What's the state of the attack to get the first preimage on MD4? Is it still this http://www.di.ens.fr/~leurent/files/MD4_FSE08.pdf in 2^102 ?
0
votes
0answers
54 views

Strength of Combining Hash functions [duplicate]

If I combine two hash functions, what will the impact on the strength of the resulting function. If I combine in following way: H1*H2 (multiply) H1 + H2 (concat) H1 Xor H2 H1 (H2) EDIT: Lets say H1 ...
2
votes
1answer
309 views

Example Rainbow Table Generation

I have read up on rainbow tables and think I understand the idea behind them. However, I find that it would be better for me to actually attempt to implement a (very basic) rainbow table generator in ...
6
votes
2answers
237 views

Attacks of the MAC construction $\mathcal{H}(m||k)$ for common hashes $\mathcal{H}$?

Consider a common practically-collision-resistant Merkle–Damgård hash function $\mathcal{H}$ (e.g. SHA-1, RIPEMD-160, SHA-256, SHA-512). We define a Message Authentication Code $\mathcal{C}$ $$(k,m) ...
3
votes
1answer
162 views

Is the last step of an iterated cryptographic hash still as resistant to preimage attacks as the original hash?

Considering a cryptographic hash, such as MD5 or SHA2, denoted by the function $H(m)$ where $m$ is an arbitrary binary string, there is a lot of material available that deals with potential weakness ...
14
votes
3answers
1k views

Reverse engineering a hash?

I understand this may not be the best place to ask a question like this, but I believe that this community may be the best/only place I can ask such a question. I have inputs and outputs from an ...
12
votes
2answers
329 views

What is the general justification for the hardness of finding preimages for cryptographic hash functions?

Since most cryptographic hash functions are simple, compact constructions does this simplicity impose a limit on the complexity and the size of a function that can generate preimages? That is, given a ...