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Jan
7
comment Permutation of keys that guarantees different hashes
You might want to clarify your question. The only functions that satisfy $H(x) = H(y)\ \forall x \ne y$ are constant ones, and those obviously cannot satisfy the second criterion. So, as written, the answer is trivially "no."
Jan
7
answered 2 Part Encryption
Jan
7
reviewed Close how to change math.random() implemented in javascript to securerandom
Jan
6
comment Hash function that allows to decide if A > B if you only have hash(A) and hash(B)?
Related, not quite duplicate: crypto.stackexchange.com/questions/8160/…
Jan
6
revised Uniformly distributed secure floating point numbers in [0,1)
added 167 characters in body
Jan
6
revised Homemade Randomized RSA
"mod" -> "\bmod", misc. copyedits
Jan
6
comment Homemade Randomized RSA
You can use the public key to implement an encryption oracle, but that's not the only thing you can do with it. So, you know $e$ (since it's public), and have a guess for $m$. What can you do with those? Will it help you answer @Henrick's question?
Jan
3
comment Is there an asymmetric encryption algorithm where the public key cannot be derived from the private key
I just posted a question about the security of this scheme.
Jan
3
asked Could this “symmetric RSA” scheme provide key compromise resistant communications?
Jan
3
comment Is there an asymmetric encryption algorithm where the public key cannot be derived from the private key
Hmm, yes, that might work. You'd presumably need a non-standard way of generating $e$ and $d$ (since simply setting e.g. $e = 65537$ is obviously a non-starter here), but just picking a random $e$ coprime to $\lambda(n)$ might work. I've never seen any actual security analysis for this RSA variant, though; in particular, I wonder just what kind of message padding it would need to be secure both as an encryption scheme and as an authentication scheme at the same time.
Jan
3
revised Is there an asymmetric encryption algorithm where the public key cannot be derived from the private key
added 209 characters in body
Jan
3
comment Is there an asymmetric encryption algorithm where the public key cannot be derived from the private key
Doesn't knowing both the encryption and the decryption exponent allow factoring the modulus?
Jan
3
answered Is there an asymmetric encryption algorithm where the public key cannot be derived from the private key
Jan
3
comment What is the correct definition of the blowfish F-function?
It seems to me that you've misinterpreted the pseudocode here while translating it to C: the code is clearly using x + y mod 2**32 to mean "add x and y modulo 2**32", or, in other words, "add x and y using 32-bit integer arithmetic" -- not "reduce y modulo 2**32 and add the result to x" like your C code reads.
Jan
3
comment Uniformly distributed secure floating point numbers in [0,1)
@user: I did. There does not appear to be any basis for that assertion, as the code given in the answer actually gives exactly the same results as casting to float and dividing.
Jan
3
comment Why does DES implement so much Cross Wiring?
@RichieFrame: Your comment seem to directly contradict the answer given by Yehuda Lindell below. If you don't agree with the answer, or think there's more to this, you might want to consider adding an answer of your own.
Jan
3
revised Uniformly distributed secure floating point numbers in [0,1)
added 594 characters in body
Jan
3
answered Uniformly distributed secure floating point numbers in [0,1)
Jan
2
answered Continuous stream of strong randomness from limited entropy?
Jan
2
comment What is the difference between key size and block size (for AES)
I'm not 100% sure what you're trying to ask here, but I am pretty sure that, whatever it is, it's probably too broad to be effectively answerable here. You might want to start by picking up an introductory book on cryptography, which should explain how block ciphers like AES work, and how they can and should be used.