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Oct
3
comment Calculating ciphersize of Paillier, SSE and OPE
A Paillier ciphertext will be a lot longer than 64 bits. Probably more like 4096 bits (assuming a 2048-bit key, which is about the level needed to provide good security today, given the state of modern factoring algorithms).
Oct
3
comment Reordering non-block-aligned parts with DES in ECB mode
Can you tell me the context where you ran into this? What makes you think it is possible to exchange the first line with the last? Why are you so set on that specific goal? That seems awfully specific (as opposed to, say, swapping some pair of entries of the attacker's choice). I assume you know that you can swap any pair of ciphertext blocks, and the corresponding plaintext blocks will be swapped? So if you can find a pair of blocks that, when swapped, leaves the format of the plaintext undisturbed (and such that the exchange is favorable to the attacker), that's a valid attack.
Oct
3
revised Generate key pair deterministically from a particular seed
Clean up teh question and title.
Oct
3
revised Using multiple secret keys
added 168 characters in body; added 40 characters in body
Oct
3
answered Using multiple secret keys
Oct
3
comment Using multiple secret keys
Yeah, that's not gonna work. Someone who is not physically at the specific location, but who knows where the specific location is, can still infer the key and decrypt the ciphertext. There's been academic work on this sort of problem (e.g., by Dorothy Denning), but it's a much harder problem than you seem to realize.
Oct
2
comment Extracting only the entropy
@Blaze, oh, good grief. No it doesn't. Read the paper. Nowhere does the paper say "/dev/random is no good". I challenge you to find anywhere where it says that. If you are thinking of the title ("/dev/random is not robust"), by 'robust' they are referring to a particular technical/mathematical definition of robustness. Failure to meet that definition doesn't mean that "/dev/random is no good". As the abstract says "it remains unclear if these attacks lead to actual exploitable vulnerabilities in practice".
Oct
2
comment Using multiple secret keys
Why do you want to use these keys? What are your goals? What threat are you trying to avoid? What are you trying to achieve? What bad outcomes are you trying to avoid?
Oct
2
comment Extracting only the entropy
@Blaze, OK, well, I'll put it this way then: it sounds to me like you may be drawing unwarranted and overly strong conclusions. The research you cite does not imply that "/dev/random is no good" (nor do the authors of those papers make broad claims like that). Be careful; cryptography is a subtle and nuanced business, you can't always reduce things to simple sound bites.
Oct
2
reviewed Approve attribute-based-encry tag wiki excerpt
Oct
2
reviewed Approve attribute-based-encry tag wiki
Oct
2
comment Paillier Crypto System : Pros and Cons?
Please also make sure to describe what research you've done. We expect you to show some evidence of effort on your own before asking. Make sure to read the help center.
Oct
2
comment Extracting only the entropy
@Blaze, careful there. There is no good way to do accurate entropy estimation (at least not in general, without knowing anything about the source). But be careful about what inferences you draw. That doesn't mean /dev/random is no good. In general, there's a lot of work on this sort of topic; I encourage you to read up on it before drawing too many conclusions.
Oct
2
comment Extracting only the entropy
@CodesInChaos, Ahh, that might explain it. Thank you! That would suggest the follow-up question: why does he/she want that? If we knew the source of this requirement, there might be a better solution. (Especially when /dev/random already exists...)
Oct
2
comment Extracting only the entropy
I don't know what you mean by "inject pseudo entropy". A hash does not inject entropy. I'm not familiar with "pseudo entropy" as a technical term. Can you tell us more about what your real problem is? You might want to edit the question to provide more context and to explain the particular application setting and what you're trying to achieve or what problem you're trying to fix.
Oct
1
answered Extracting only the entropy
Oct
1
comment Estimating bits of entropy
Can you tell us more? Why do you want to measure the amount of entropy? What do you know about the source of the byte stream? The answer is going to depend heavily on the answers to these questions and on other details, so if you can give us more details, we might be more likely to be able to give you a good answer. This is not a simple subject with a simple one-line answer...
Oct
1
comment How to calculate y value from ((y*y) mod prime) efficiently
Duplicate of crypto.stackexchange.com/q/6518/351
Sep
30
answered Why should I make my cipher public?
Sep
30
answered Non-interactive proof that an element is in a subgroup