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Dec
3
comment Generalizing the conversion of Diffie-Hellman to El Gamal
I suppose this depends on what you understand with "two-round key-exchange protocol". Diffie-Hellman is actually only one round, since the message from Alice to Bob and the one from Bob to Alice are completely independent from each other. We need a KE protocol which is secure against repetitions of the first message (as this is Alice's public key).
Dec
2
revised Why is MixColumns omitted from the last round of AES?
why is this combination efficiently implemented together?
Dec
2
revised A mathematical explanation of the DES encryption system
formatting, adding some links
Dec
2
comment How much would it cost in U.S. dollars to brute force a 256 bit key in a year?
Factoring 256-bit numbers is not really a big problem nowadays, and is much faster than brute-forcing a similar-size key. The RSA key sizes where factoring needs a quantum computer are much larger. (Welcome to Cryptography Stack Exchange, by the way.)
Dec
2
comment How do we find the last two correspondences in an otherwise known even permutation?
@jug: a \over b results in $a \over b$. You can get a binomial coefficient by \binom{a}{b} = $\binom{a}{b}$. (I was so free to edit your comment.)
Nov
30
comment How to generate a list of unique random strings?
Welcome to Cryptography Stack Exchange. Sorry, your question is not clear. Do you want to know how to use the output of a random number generator to generate such a list? (Then this would be off-topic here, and might be better on Stack Overflow.) Or do you want to create a random number generator? (Then it still lacks information ... or it simply gets a list of known RNG algorithms, and list-questions are off-topic here.)
Nov
30
comment Software implementation of a commutative cipher?
Do you have a reference for Pohlig-Hellman? A very short googling finds only an algorithm for calculating discrete logarithms, and I don't see how this would apply here.
Nov
30
revised Software implementation of a commutative cipher?
It doesn't work this way - thanks to poncho for pointing this out.
Nov
30
comment Is it a good idea to use bitwise XOR on a set of MD5 sums?
@fgrieu: Thanks for the note. Such occasions are when I wish I could downvote my own answer.
Nov
30
revised Is it a good idea to use bitwise XOR on a set of MD5 sums?
added 530 characters in body
Nov
30
revised How can I make my cipher show the avalanche effect?
spelling (sorry, cypher looks just wrong).
Nov
30
comment How can I make my cipher show the avalanche effect?
If you want any constructive answers, you should show how your cipher currently works (in mathematical formulas, preferable). Then we can have a look to see how to improve it.
Nov
30
revised How can I make my cipher show the avalanche effect?
formatting, tags
Nov
30
comment How can I make my cipher show the avalanche effect?
Welcome to Cryptography Stack Exchange. @Avinash, your question was migrated here because it is more on-topic here than on Stack Overflow. Please register your account here to be able to comment and accept an answer.
Nov
30
revised Protocol to generate Client Certificates at the start of a SSL session automatically?
link update
Nov
30
reviewed Approve Is it a good idea to use bitwise XOR on a set of MD5 sums?
Nov
30
answered Is it a good idea to use bitwise XOR on a set of MD5 sums?
Nov
30
comment Is it a good idea to use bitwise XOR on a set of MD5 sums?
One property of XOR is its commutativity (and associativity) - A XOR B XOR C = B XOR C XOR A, i.e. you can't detect changes in order, but at the same time, you don't have to sort before aggregating. No idea if this is positive or negative for your use case.
Nov
30
comment Hash or encryption function for challenge-response protocol?
Don't use MD5, it is broken (i.e. not collision-resistant any more). Even if it might be secure in your protocol, it is better for your reputation to use SHA-2 instead.
Nov
29
answered Software implementation of a commutative cipher?