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May
19
comment secure dynamicaly growing memory (libsodium)
This is more a programming question than a crypto question. See en.wikipedia.org/wiki/Data_structure_alignment. I believe you need to care about alignment, and so you should not malloc less than 64 bits.
May
15
comment Practical Uses for Timing Attacks on Hash Comparisons (e.g. MD5)?
There's no timing attack on MD5 as used here because there is no secret to extract. You have provided the password parameter, you know exactly what the internal state of the hash will be through the entire invocation. If you were trying to extract a salt, then maybe you could contemplate a timing attack. @fgrieu is correct about the comparison being vulnerable.
May
6
comment Information-theoretic bound on leakage by timing measurement
That occurred to me too. I figured I'd write up what I had so far.
May
6
answered Information-theoretic bound on leakage by timing measurement
May
6
comment SSL-connection between client and server: how can one make this connection secure?
C needs some way to know that the cert belongs to S. Why isn't there identifying information in the cert? The alternative is some out-of-band way to know the cert is correct, e.g. pinning.
Apr
3
revised Solve a problem, thought it was hash length extension, hours later, am I wrong?
added 316 characters in body
Apr
3
answered Solve a problem, thought it was hash length extension, hours later, am I wrong?
Feb
9
comment Client-Server application how can data be encrypted so only clients can read it
There has to be some kind of authentication framework, since encrypting data is pointless unless you can verify that you're communicating with the correct person. If this is just random strangers sharing data there's no way to tell if one of them is (acting on behalf of) the server.
Feb
6
answered Client-Server application how can data be encrypted so only clients can read it
Jan
30
awarded  Yearling
Jan
30
answered Is there any existing cipher capable of scaling from a 1 bit key up to a one-time-pad?
Jan
22
comment Compact digital signature for noisy data
@fgrieu Reed-Solomon codes are non-binary, I think they can be defined over any $GF(q)$. See Wikipedia
Dec
12
comment Recovering a constant salt for MD5
"I know that the hash is of length 21" - "hash" should be "salt", no?
Dec
2
comment Using the same symmetric key in both directions?
If your attacker can't inject messages then that's not something you have to worry about. TCP provides less of a barrier than you seem to think, though.
Dec
2
comment Using the same symmetric key in both directions?
@horsehair No, the attacker wouldn't replay the TCP packets, they would replay the message in new TCP packets that go the other way.
Nov
25
comment Minimum number of independent trials needed to detect a bias
Is this just confidence intervals for a binomial distribution?
Nov
20
comment BruteForcer XOR (bfxor.exe) to attack 64-bit keys and longer
That KGB agents found themselves in this scenario once doesn't imply that it is a "common mistake", especially in the digital age. In addition, there is no reason to believe that the reused pad would be just a handful of bytes reused as many times as is necessary to encrypt an entire file. It's an interesting problem and I'm certainly not telling you to stop your pursuit, but I am absolutely not convinced that it is of any practical value.
Nov
18
comment BruteForcer XOR (bfxor.exe) to attack 64-bit keys and longer
"Now this may all be laughable in 2014 though where most cryptographers and even I use 2048 to 8192-bit (256 to 1024 Bytes) Keys for XOR encryption" - No cryptographer in 2014 is using anything like a vigenere cipher.
Nov
14
comment Random Permutation polynomial
I'm not convinced that limiting the degree of the polynomial serves a purpose, and you have the problem that low-order permutation polynomials aren't going to be very random. $x + a$ defines a permutation for every $a$, but it's just a set of permutations of size $p$.
Nov
11
comment Random Permutation polynomial
1) That's different enough that you should probably ask separately 2) I don't know 3) it doesn't really sound like a crypto question anymore, mathoverflow.net might get you better answers.