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Jun
17
answered Brute-force attack given multiple hash prefixes
Jun
17
comment Brute-force attack given multiple hash prefixes
There's no "big question" here. SHA-1 is almost certainly such a function -- if it wasn't, it would be horribly broken, and we probably would have noticed this deviation from random from now. So from the perspective of an attacker, yes, an attack can absolutely treat SHA-1 in this way. As a result, the bottom line is: 2 candidates are enough to filter down to the true secret. Universal hash functions are a distraction, and the last paragraph introduces uncertainty that doesn't really exist in practice.
Jun
7
revised Is randomsound for increasing entropy pool not doing what it is supposed to do?
deleted 7 characters in body
Jun
7
comment Is it possible to choose which point will have the public key of a given Elliptic Curve?
What are you free to choose? Are you free to choose the generator? The definition of the curve? (i.e., the equation defining the curve) Or are those fixed? Please edit your question to clarify -- as it stands it can't be answered definitively, as the answer depends on those constraints.
Jun
4
comment How do we know a cryptographic primitive won't fail suddenly?
You can't be sure. You can't be sure any of them are secure, and you can't be sure you'll have advance warning of a break. See What's the mathematical model behind the security claims of symmetric ciphers and digest algorithms? and How to prove the security of the PRNG? for more.
May
20
answered Severity of Cooking NIST P Curve Constants
May
18
comment Is what i'm trying to do safe?
@VincentAdvocaat, what I meant was that you didn't mention you had tried specifically TLS with pre-shared keys....
May
17
comment Is what i'm trying to do safe?
@VincentAdvocaat, then you should mention that in the question. We expect you to tell us what you've considered and what you've tried in the question. No one likes taking the time to write an answer and then have the original poster come back and say "I already knew of that".
May
15
comment Is what i'm trying to do safe?
@SOJPM, pre-shared keys for TLS seem like a counterexample to the claim that TLS handshakes always require asymmetric crypto -- no?
May
15
revised Is what i'm trying to do safe?
added 108 characters in body
May
15
answered Is what i'm trying to do safe?
May
6
comment Brute-force attack given small search-space and hash prefix
This answer is incorrect. It assumes we only have 8 bits of the hash, but as the OP has clarified, we actually have 32 bits of the hash.
May
6
comment Brute-force attack given small search-space and hash prefix
I encourage you to edit the question to incorporate this information. Comments exist to help you improve the question; clarifications shouldn't be left in the comments, as they can disappear at any time, and readers shouldn't need to read the comments to understand what you're asking.
May
6
answered Brute-force attack given small search-space and hash prefix
May
6
comment Brute-force attack given small search-space and hash prefix
What's a character, in terms of bits, in your implementation? Is the output of sha1_hex() in hex, so each character is 4 bits of the hash, and the first 8 characters are the first 32 bits of the SHA1 hash?
Apr
27
comment Can cycle finding techniques reduce the memory usage of the MitM attack against 2DES and 3DES?
Yes, it works. It's a standard trick; kudos for re-discovering it. I see no reason the table size would amount to $2^{n/2}$. The complications in working out exact parameters arise when you work out the details of (a) parallelism, (b) distinguished points, (c) the cost of memory and routing networks, to get the exact optimal tradeoff (if you care about constant factors).
Apr
26
comment Adding two public keys
@RickyDemer, I don't know. I guess that's a different question. If you're suggesting that might be what the OP wanted, if so, he needs to specify his requirements or goals in the question. Right now the question only asks for "another, more widely used" scheme. I can only answer the question that was asked....
Apr
26
comment Is there are code hidden in Wired Magazine's December 2014 Issue?
@jww, are you sure you've got the right site? This question is clearly off-topic for PP&CG: codegolf.stackexchange.com/help/on-topic
Apr
26
answered Adding two public keys
Apr
15
awarded  Popular Question