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Feb
27
answered Are there any practical implementation of a homomorphic hashing or signature scheme?
Feb
27
revised Are there any practical implementation of a homomorphic hashing or signature scheme?
correct a typo
Feb
27
comment Are there any practical implementation of a homomorphic hashing or signature scheme?
sashank, I think you might need to specify more precisely exactly what you mean by homomorphic hashing.
Feb
27
revised Is Truecrypt's multiple/cascading encryption safe?
Eliminate a lot of the ranty bits. Focus on the question, and remove the undocumented assertions. Be less argumentative. Try to identify a question that is objectively answerable.
Feb
23
answered Why nobody considers counter re-keying as a standard Block Cipher Mode?
Feb
23
comment Why nobody considers counter re-keying as a standard Block Cipher Mode?
Your question is based upon the assumption that nobody has considered this alternative. That assumption is wrong. Please rephrase the question to avoid making such tendentious assumptions.
Feb
23
comment Is Guillou-Quisquater existentially unforgeable against adaptive message attack under a random oracle model?
Samuel, can you edit your question to fix any such typos? These details are important. You can click the little "edit" button at the bottom of your post to correct it. Thank you!
Feb
22
comment Computational indistinguishability and example of non polynomial algorithm
@wmnorth, I've edited my answer to give a natural answer that arises in distinguishing two probability distributions, but I'm starting to get the impression that I'm not going to be able to help you until you can more precisely state exactly what you want to know (and what you've already tried and where you got to stuck).
Feb
22
revised Computational indistinguishability and example of non polynomial algorithm
added 450 characters in body
Feb
22
comment Computational indistinguishability and example of non polynomial algorithm
@wmnorth, sorry, I can't make any sense of your question. I think you must have some hidden assumptions, or must be asking a different question than what you really want to know. What does it mean for an algorithm to take exponential time when trying to distinguish two probability ensembles/ It just means that the running time is exponential. I really don't understand what the confusion is. (If you are asking for a natural example of an exponential time algorithm for distinguishing two probability distributions, that's different; if so, edit your question!)
Feb
22
comment Computational indistinguishability and example of non polynomial algorithm
@wmnorth, any algorithm that spends, say, exponential time doing some computation before producing an output. (I suspect I must not be understanding your question; why don't you try explaining what you real confusion is?) Have you studied running time analysis of algorithms? If not, any good algorithms textbook should have something on big-O notation and running time analysis -- I very much recommend you read it.
Feb
22
answered homomorphic encryption special case of multi party computation?
Feb
22
revised Computational indistinguishability and example of non polynomial algorithm
added 334 characters in body
Feb
22
answered Computational indistinguishability and example of non polynomial algorithm
Feb
20
answered Why is RSA encryption significantly faster than decryption?
Feb
18
comment AES encryption with shared IV
If you follow this strategy, make sure to use a different key for generating the IV from the counter than you use for the actual encryption (where you use that IV), otherwise bad things could possibly happen.
Feb
16
comment Low complexity implementation of a small blocksize cipher (< 64 bit)
@TheLazyEngineer, it sounds like you might be making one of the most common crypto mistakes around: you are using encryption without message authentication, which is usually a mistake. It's important to use message authentication, to prevent forgery (and by the way, if you do, then your concerns about avalanche will go away).
Feb
15
comment Low complexity implementation of a small blocksize cipher (< 64 bit)
I think PRESENT is optimized for hardware implementations. I don't know whether there's a variant with a 44-bit block size. If you're OK with a 64-bit or larger block size, Skipjack and RC5 are also worth a look: they're very convenient for embedded microprocessors.
Feb
15
comment Low complexity implementation of a small blocksize cipher (< 64 bit)
@Thomas, yes. I agree with everything you wrote. On your question: Yes, $1 - e^{-b^2/2^{45}}$ is a more accurate estimate. However, if $b$ is much less than $2^{22}$, then $1 - e^{-b^2/2^{45}}$ is approximately equal to $b^2/2^{45}$ (using the approximation $e^{-x} \approx 1-x$ when $x>0$ is much smaller than 1).
Feb
15
answered Extract private RSA key from USB cryptographic token using Bardou et al. attack (variant of “million message attack”)