CodesInChaos

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bio website github.com/CodesInChaos
location Munich, Germany
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visits member for 1 year, 11 months
seen 11 mins ago
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Aug
31
 comment HRNG for One Time Pad
@SimonJohnson Pretty much any universal hash works fine in that way. If done correctly, an attacker has a certain chance that his forged message gets accepted, and no matter how big is computational power, he can't increase that chance. The chance increases with the message length, but you can easily choose your parameters so that it's still extremely low.
Aug
31
 revised How to submit a new method of encryption?
edited body
Aug
31
 comment No SHA-1 Collision? Yet SHA1 is broken?
@fgrieu I think the reason people care so little is because it's a generic attack against the mode, which is used by most current(Pre-SHA-3) hashes. If there were an attack against the compression function of similar strength that'd do much more damage to the reputation of the hash. And of course the number of compression function calls an attacker needs is still around $2^n$. [btw 2 k is the number of blocks, not k]
Aug
30
 revised No SHA-1 Collision? Yet SHA1 is broken?
added 599 characters in body
Aug
30
 comment Can I build a secure tweakable block cipher from a normal one by adding key and tweak?
I never understood why DES was treated as having a 64 bit key, and not a 56 bit key.
Aug
30
 answered No SHA-1 Collision? Yet SHA1 is broken?
Aug
30
 comment Do I have to have a different salt for each password?
How many valid passwords are there in your database?
Aug
30
 answered Do I have to have a different salt for each password?
Aug
30
 comment Proof of work for standard computers
@DavidSchwartz The please post an answer that describes an algorithm. I for one see no way to make collisions of any kind work. My impression is that a computer with 1GB memory and a billion cores would solve your problem a billion times as fast as a computer with a single core, since there are n^2 possible pairings he can pick from to compare.
Aug
30
 comment Proof of work for standard computers
@DavidSchwartz You need to make it work well on standard computers, and hard on specialized computers. And at least for hamming-distance I don't see what kind of algorithm you envision.
Aug
30
 comment Proof of work for standard computers
For hamming distance, I don't know what data structure the worker should use to efficiently check if a near-collision occurred. If you think hamming distance works well, please post an answer describing how it would work in practice @DavidSchwartz.
Aug
30
 comment Proof of work for standard computers
For prefix collisions it's properties are much worse than a prefix pre-image with the same hash function(scrypt or plain hash). An attacker who as large shared memory and many small parallel If you want to use high memory requirement to give an advantage to a CPU, the worker must not be able to share that memory between cores. That's because a PC has a lot of memory per core, but the total amount of memory isn't larger than that of the attacker.
Aug
30
 revised Proof of work for standard computers
added 9 characters in body
Aug
30
 comment Which blind signature schemes exist, and how do they compare?
The problem is finding a scheme that's actually secure/production ready. If you're referring to A Novel Untraceable Blind Signature Based on Elliptic Curve..., it gives me a bad feeling. It seems like there is a way for the requester to obtain two valid signatures in one operation. And it's generally very sloppy.
Aug
29
 reviewed Approve suggested edit on ntru tag wiki
Aug
29
 reviewed Approve suggested edit on proof-of-work tag wiki excerpt
Aug
29
 reviewed Approve suggested edit on ntru tag wiki excerpt
Aug
29
 reviewed Approve suggested edit on proof-of-work tag wiki
Aug
29
 comment Random Sequence Generator function
Please don't cross post. Nobody suggested you should. Someone suggested a migration, and even that was dubious.
Aug
29
 comment Is this a good way to encrypt a file?
Your salt encryption step doesn't make much sense. Why not just include the plain salt?
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