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Oct
14
comment Adding tweak to a block cipher
(besides, the Skein designers had incentive to keep the Threefish key schedule as simple as possible - it needs to be run for every compression function invocation of the hash function, and the Threefish permutation itself is already not that expensive relative to its key schedule)
Oct
14
comment Adding tweak to a block cipher
@LightBit Correlating "simple" with "weak" is a mistake unless you have references to back up the claim for the Threefish key schedule being vulnerable to attacks. I think this is what owlstead was referring to.
Oct
9
comment Breaking RSA moduli
You will have to define "break" and "RSA moduli" - do you mean "factor" and do "RSA moduli" need to resist factorization, or do you mean any semiprime?
Oct
8
awarded  Nice Answer
Oct
6
comment Is there a string that's hash is equal to itself?
@fgrieu Indeed :) but it's pretty clear which answers I was referring to. +1'd your answer
Oct
6
comment Is there a string that's hash is equal to itself?
Please note both answers below are either misleading or do not quite follow. I do not have time to write an answer now, but someone else surely will. In the meantime, feel free to look at these couple of near-duplicates: crypto.stackexchange.com/questions/9910/…, crypto.stackexchange.com/questions/971/… (they don't contain an answer to your question, but provide good insights into how to answer this kind of question). Also, keyword "fixed point".
Oct
1
comment Small Encryption Exponent
@fgrieu If this is indeed the expected resolution path, it will be somewhat difficult to produce a solution before the deadline at this point :-)
Oct
1
comment Small Encryption Exponent
To elaborate a bit on poncho's comment, most real world RSA encryption schemes use small encryption exponents for performance, usually 3, 17 or 65537 - so $e = 7$ may not be of any help!
Sep
30
awarded  Explainer
Sep
24
awarded  Autobiographer
Sep
21
comment How much would it cost in U.S. dollars to brute force a 256 bit key in a year?
@AwalGarg Bruce can do it by simply guessing the key on the first try.
Sep
3
comment AES-ECB as an authentication mechanism
What is "Y" here? The ciphertext?
Aug
28
comment Is there a hash function which has no collisions?
@supercat and David you may want to create a chat room to discuss this (long comment chains like these tend to get automatically deleted after a bit)
Aug
9
awarded  Nice Answer
Aug
4
comment Theoretical attack on RSA
@Entimon If $p$ and $q$ are known to be close to one another, then, yes, it is fast (just like Fermat's algorithm), but if $p$ and $q$ are chosen properly (or even randomly, for sufficiently large $p$ and $q$) then $\lvert p - q \rvert$ is on the same order as $\sqrt{N}$, and in the same realm: infeasible.
Aug
1
revised Theoretical attack on RSA
fixed typo
Aug
1
revised Theoretical attack on RSA
added some notes and a bunch of links
Aug
1
answered Theoretical attack on RSA
Jul
26
comment Reversing DJB2 Hashes
Hint: I can tell you that the number I'm thinking of is even (0 modulo 2), that's not going to help you know if I'm thinking of 2, 4, or 34857188414. That information is lost when you reduce your input modulo 2^32, only the remainder remains, the original value is lost (yes, forever).
Jul
24
comment Low Public Exponent Attack for RSA
@CGFoX If you had only two congruences then your $n'$ would be on the order of $n^2$ (product of two moduli) and so your $m^3$ would be larger than $n^2$ (by an order of $n$) and you couldn't easily take the cube root without knowing the factorization of the moduli, so it doesn't work.