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Dec
6
comment Can insecure algorithms be combined to form a secure algorithm?
Also, they are hoping it will be safe, but there is no proof that this is safe.
Dec
6
comment Slow one-way pseudo-random permutation?
Also, why does your application require such a complex construct? Why not just store a unique random serial number in the 2-D barcode, and have a back-end database that maps the serial number to whatever data is associated to that card (of course, the data can be encrypted under one merchant's key if you wish). Perhaps I haven't quite understood the application yet.
Dec
6
comment Slow one-way pseudo-random permutation?
Why do you need the output to be the same length as the input? If you're willing to have (say) a 256-bit output, your goals are easy to achieve; just use the SHA256 hash. If the output is going to be stored in a database but not stored on the card, that'd suffice. Also, why do you need it to be bijective (i.e., a permutation)? If collisions are non-trivial to find, is that good enough?
Dec
6
comment Enhance CSPRNG output
@user1028028, it doesn't matter if the PRNGs are independent. What matters is that their seeds (their keys) are independently chosen. That's how you can tell: check how you've generated them.
Dec
6
revised Can insecure algorithms be combined to form a secure algorithm?
Clarify the question.
Dec
6
comment Enhance CSPRNG output
"Unrelated" is NOT the criterion. The criterion is that the keys be independently chosen, not that the algorithms be "unrelated" or "independent" (whatever that would mean). You can even use the same CSPRNG algorithm, as long as you have two independent keys.
Dec
6
comment Enhance CSPRNG output
How are they keyed? With two independent keys? Also, if one is a CSPRNG, then it cannot be biased (to be cryptographically secure means that it can't be biased).
Dec
6
comment If H(m) = 0 for some m, how can a DSA signature be forged?
As DrLecter says, when asking this sort of question, please make sure to describe what you've tried and where you got stuck. We expect you to make a serious effort before asking here and to show us what you've tried and where you got stuck.
Dec
6
comment Is an elliptic curve over $\mathbb{F}_p$ order preserving for the points $(x,y) \in \mathbb{Z}_p$?
Could you define what you mean by $E(x)=y$? If $E$ is the curve, then $E(x)$ is not well-defined. Do you mean $x,y$ such that $(x,y)$ is on the curve (i.e., $y^2=x^3+ax+b \pmod p$)?
Dec
6
comment Is there any analysis of freebsd's “geli” encrypted geometry provider?
Got any suggested links for reading about how geli works and how its crypto works? Any overviews or other resources that you think might be a helpful place to start for those who might want to start taking a look at it? If yes, that might be worth editing into your question.
Dec
5
revised How hard is to invert the function that computes the middle-bits of (x^2)?
added 465 characters in body
Dec
5
answered How hard is to invert the function that computes the middle-bits of (x^2)?
Dec
4
comment Who uses Dual_EC_DRBG?
@nymble That patent does not appear to patent Dual_EC_DBRG. Nor does it appear to patent any backdoor. Rather, the patent lists Dual_EC_DBRG in the prior art, and claims to patent a method for generating the points P,Q in a way that is verifiably free of backdoors.
Dec
2
answered Why use two affine transformations in Multivariate Cryptography?
Nov
24
awarded  Good Answer
Nov
24
answered What is the difference between a bijective random oracle and a random permutation?
Nov
21
awarded  Nice Question
Nov
20
comment How to prove this LFSR equation?
I suggest you edit the question to include that information, to make this question self-contained, as well as to define the notation $(f,g)$ and $[f,g]$ for polynomials and $+$ for solution spaces. Also, I suggest you edit the question to show what you've tried so far and where you got stuck.
Nov
18
comment Should we sign-then-encrypt, or encrypt-then-sign?
@louism, that's a separate question. This isn't a discussion forum -- questions should be posted separately (see the Ask Question on the upper right). But make sure to first read the help center, and do your research (try to answer the question on your own using Google, Wikipedia, search on this site, etc.) before asking.
Nov
17
comment Bellovin 96' attack on IPsec ESP protocol on encryption only option
Did you read the description in the paper carefully, one step at a time? Where did you get lost? Are you familiar with other attacks on modes of operation?