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Jan
9
comment Why can’t the public key exponent in RSA be negative?
While not precisely a duplicate, at least my answer to this related question also answers yours.
Jan
9
revised Do we have anyway of knowing if avoiding self-permutation in RC4 makes it any stronger?
link to Finney's original sci.crypt post
Jan
9
revised Do we have anyway of knowing if avoiding self-permutation in RC4 makes it any stronger?
added 752 characters in body
Jan
9
answered Do we have anyway of knowing if avoiding self-permutation in RC4 makes it any stronger?
Jan
9
comment Do we have anyway of knowing if avoiding self-permutation in RC4 makes it any stronger?
Technically, since RC4 key length is capped at 256 bytes (and the key is repeated if it's shorter than that), just concatenating $k_{ip}$ and $k_u$ won't work; you'd have to actually run the key setup twice, first with $k_{ip}$ and then with $k_u$. Still, for any initial permutation $p_1$ and any target permutation $p_2$, there is an RC4 key (possibly several, in fact, but at least one is easy to find) that transforms $p_1$ into $p_2$. In that sense, every key in the OP's modified RC4 is provably equivalent to some key in normal RC4.
Jan
8
revised Permutation of keys that guarantees different hashes
deleted 15 characters in body
Jan
7
comment Rule 30 Cellular Automaton for Cryptography
This paper seems to say "no, it's not secure", but I haven't read it fully yet.
Jan
7
comment Why IV does not have to be secret yet has to be random
You may also find this question useful.
Jan
7
answered Permutation of keys that guarantees different hashes
Jan
7
comment Permutation of keys that guarantees different hashes
@fgrieu: I suspect the OP actually wants $$\exists H,m\ \forall x,y: (x \ne y \land H(x) = H(y)) \implies H(m(x)) \ne H(m(y)),$$ rather than $$\exists H,x,y\ \forall m: x \ne y \land H(x) = H(y) \land (m \ne {\rm id} \implies H(m(x)) \ne H(m(y))).$$
Jan
7
comment Permutation of keys that guarantees different hashes
@petermlm: Yes, but if $H(x) = H(y)$ for all $x$ and $y$ (that's what $\forall$ means), then the output of $H$ is constant.
Jan
7
comment What is the difference between MACTripleDES and TripleDES?
That would be a valid question on Stack Overflow, but not here. (Or you could just look at the documentation, and specifically the ComputeHash(Byte[]) method). Also, you cannot "encrypt" or "decrypt" anything with a MAC; that's not what they're for.
Jan
7
answered What is the difference between MACTripleDES and TripleDES?
Jan
7
comment What is the difference between MACTripleDES and TripleDES?
You mean this thing? If so, this question on SO might be helpful.
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