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2d
comment How broken is a xor of two multiply with carry generators?
3. The question is not well-defined. There are many variants of MWC generators. The security of the scheme might depend upon what variant you choose and what parameters you choose (e.g., the lag, the base, the multiplier, the initial carry). Can you provide a complete specification of your proposed scheme with all parameters specified? What size is the seed for each MWC generator?
2d
comment How broken is a xor of two multiply with carry generators?
1. Can you provide any motivation for this question? Why should we care? I could generate endless number of variants of a question that take the form "Consider the following rather-dubious PRNG that's probably not secure and hopefully no one uses; just how badly broken is it?", but I don't know if that'd be useful to the world at large. 2. What research have you done? What effort have you made? What is the best attack you can find on this cipher? We expect you to make a significant effort before asking here, and to show us what research/attempts you've made.
2d
comment I hashed my bag and in it I put… “Is there a hash for unordered items?”
In addition to the excellent answer below based on Merkle hash trees, you can also take a look at crypto.stackexchange.com/q/11420/351 and crypto.stackexchange.com/q/6497/351 and crypto.stackexchange.com/a/489/351 (H(sort(H(x),H(y),..))) and crypto.stackexchange.com/q/17935/351.
2d
comment I hashed my bag and in it I put… “Is there a hash for unordered items?”
possible duplicate of Hash of multiset of values, which lets me compute the hash of the union
Jun
29
comment What is a “lattice” in cryptography?
What research/self-study have you done? We expect you to do some research on your own before asking. See crypto.stackexchange.com/help/how-to-ask. Your question is covered in many standard places, e.g., textbooks and Wikipedia. If your question is answered in the obvious place on Wikipedia, you probably haven't done enough research before asking.
Jun
22
comment Which symmetric cipher is best for studying?
Study, for what purposes? What are your study goals? What do you want to learn? This will greatly affect the answer. (Also, you seem to have an implicit premise that the best way to learn whatever it is you want to learn is by devoting your time to studying a single modern symmetric cipher. I think there's a good chance that premise is not accurate.)
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
comment Creating a LCG with m = 32767
I'm voting to close this question as off-topic because it's not about cryptography. Non-cryptographic PRNGs are off-topic here.
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
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
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
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
5
comment Will ANY prior knowledge assist in determining contents of a SHA1 hash?
@InfernusDoleo, you'll be fine, if that 26-character secret key is truly secret and chosen uniformly using a crypto-quality randomness source. That large secret key means that the space of candidate inputs is very large, so brute-force won't work. The fact that you can see many outputs with related inputs doesn't help given that the secret key is so large.