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10h
comment Client-server authentication protocol suggestion
Also, this question would be a better fit for Security.SE, as it is more a question about protecting a deployed system than about the crypto.
10h
comment Client-server authentication protocol suggestion
"I know that I could just use SSL, but I would like to (for some reasons)" - What does that mean? Did you leave out some words? What would you like to? And what are the reasons? The first question a security professional is probably going to ask is: why not just use SSL? I encourage you to edit the question to make this clearer, if you'd like to get useful responses.
1d
comment Is it possible to forge elgamal in a determinsic way?
El Gamal signatures are not forgeable, when properly used.
1d
comment Is the strength of RSA over quadratic or other cyclotomic fields as strong as over the integers?
Can you explain what you mean by "compose the modulus of some other quadratic ring"? Do you mean that instead of multiplying two integers to get the modulus, we multiply two elements of some quadratic ring? Have you worked out what the corresponding version of Euler's lemma is? What is the order of the multiplicative group of such rings? What's the motivation for your question? Are you hoping to get a cryptosystem that will be faster than RSA, for a given security level?
2d
comment Are there any elliptic curve asymmetric encryption algorithms?
Thanks, DrLecter! Makes sense! On re-reading the question, the question is not as clear as I initially thought. The question says "Is there an algorithm which employs elliptic curve cryptography, fast asymmetric encryption, [...]" - I took that to mean it wants the encryption operation to be fast, like in RSA, but it's entirely possible that might not be the right reading. Perhaps the original author will take a moment to edit the question and make what he/she is looking for clearer.
2d
comment Are there any elliptic curve asymmetric encryption algorithms?
Those are all good schemes, but doesn't the question ask for encryption to be fast like in RSA? Do any of these schemes support encryption that is as fast as RSA's encryption? As far as I can tell, none of them are -- have I misunderstood? I think there's a tradeoff: RSA encryption will be faster than the ECC schemes; the ECC schemes will be faster for everything else, and will have shorter keys.
Apr
16
comment What happens if biometric data is stolen?
In addition, we expect people to do serious research on their own before asking, and to show us what they've done. There's a lot that has been written on this subject; you should try doing some searching on this topic before asking. For instance, have you tried Bruce Schneier's blog and books? Have you read through Wikipedia? Have you read standard introductions to biometrics, e.g., in Ross Anderson's Security Engineering book?
Apr
14
comment In Pedersen Key Distribution, can the public key be persistent?
Are you saying there is an attack if you re-use $(p,g,h)$ too many times? Are you saying that existing proofs don't make any promises if you re-use $(p,g,h)$ too many times? Can you give some intuition for what the nature of the alleged trouble is? I find it hard to believe that there is a real problem. It is bog-standard to re-use the public key $(p,g,h)$ in discrete-log-based cryptosystems; is there any reason that Pederson would be different?
Apr
7
comment How could Fully Homomorphic Encryption support power operations?
My perspective: The answer says that XOR and AND are universal, and thus any operation, including addition and multiplication, can be built out of XOR and AND gates. That is a correct statement. So the answer seems fine to me. But we can agree to disagree (or have a slightly different reaction) -- nothing wrong with that!
Apr
7
comment How could Fully Homomorphic Encryption support power operations?
@poncho, I don't understand your comment. This answer looks correct to me. The answer never says "ADD==XOR", does it? XOR and AND are universal; no need for NAND.
Apr
7
comment How could Fully Homomorphic Encryption support power operations?
You already answered your own question. "It enables arbitrary functions..." Power is a function.
Apr
7
comment Is it possible to determine or estimate the period for Blum-Micali PRG?
The premise seems faulty. Cycles can occur even if there is no fixed point. So, focusing on fixed points seems mis-placed, if you really care about cycles. But, as I explain in my answer, worrying about short cycles is also mis-placed concern.
Apr
6
comment Wrong Test Vector for HKDF with HMAC-SHA256
This question appears to be off-topic because it is about software development (try StackOverflow).
Apr
5
comment Should we MAC-then-encrypt or encrypt-then-MAC?
I edited the answer to more clearly express the point Josef was trying to make. Personally, I think the answer is fine (I upvoted it).
Apr
3
comment What are the exact steps to decryption in International data Encryption Algorithm (IDEA)?
What research have you done? Have you read the IDEA spec? Have you read reference code? We expect you to do some significant research on your own before asking here.
Apr
3
comment Key-dependent encryption in TAHOE-LAFS
What is ENC, specifically? How is it instantiated?
Apr
2
comment Combining multiple symmetric encryption algorithms - implications?
@StephenTouset, oh, right, thank you! Boy that was a dumb thing to write. :-) I appreciate the comment.
Mar
31
comment Can a commutative block cipher be indistinguishable from a random permutation, for fixed key?
@fgrieu, yes, maybe posting a separate question would be best. When you do, can you spell out how we choose a random set of permutations with the commutativity property? Is that notion uniquely defined?
Mar
30
comment HKDF vs TLS PRF. Which of the one is better?
Better, in what sense? More secure, in what sense? For what purposes? Under what threat model? This question is too vague as it stands; I suggest you edit it to make it more specific.
Mar
30
comment Is it possible to find an attack that can reduce the key space of the Hill cipher with $d*d$ key matrix to $26^d$
You tagged your question with hill-cipher. Look through the other questions with the same tag, and you'll find plenty of attacks on the Hill cipher that reduce the key space far further. There are also standard attacks described all over the Internet. Next time, please do more research before posting. We expect you to make a serious effort on your own to answer your own question before asking here.