Reputation
Next tag badge:
384/400 score
80/80 answers
Badges
1 36 82
Impact
~570k people reached

Feb
10
comment Diffie-Hellman Application
You don't have (3) correct; Alice sends Bob $116/123$, Bob sends Alice $95/123$, and their secret key is $62/123$. How did I get that? Well, consider the group operation, and if $a=p/q$, what is $a\Diamond a\Diamond ... \Diamond a$
Feb
10
revised FIPS-Compliant SHA2
added 66 characters in body
Feb
10
answered FIPS-Compliant SHA2
Feb
9
reviewed No Action Needed CBC-MAC: is it secure to authenticate a fixed length ciphertext?
Feb
9
answered Save the last cycle in GCM GHASH calculation
Feb
8
comment Finding $x$'s parity in the discrete log problem
In particular, what is $g^{x(p-1)/2}$ if $x$ is even? What is it if it is odd?
Feb
8
comment In a group, is it hard to calculate the base $g$ given $g^a$ and $a$?
@fkraiem: if $1/a$ doesn't exist (that is, if $a$ and the group order $q$ are not relatively prime), then $g$ won't be uniquely determinable (if one exists, there might not); however it wouldn't be difficult to find a $g$ that does work (assuming, of course, that such a $g$ exists)
Feb
8
reviewed Looks OK In a group, is it hard to calculate the base $g$ given $g^a$ and $a$?
Feb
8
comment In a group, is it hard to calculate the base $g$ given $g^a$ and $a$?
@fkraiem: It's the multiplicative inverse of $a$ modulo the order of the group (which would be $p-1$ if we're working in the group $Z_p^*$)
Feb
7
answered Is $f(x)\oplus x$ a one-way function?
Feb
6
comment Can you exchange a shared key without any hardness assumptions?
@cpast: you could argue that, with QKD, the exchanges can be listened in on (with the caveat that if you do, that'll be detected...)
Feb
6
comment Can you exchange a shared key without any hardness assumptions?
Does Quantum Key Distribution count?
Feb
5
reviewed No Action Needed compression with codebook and Cryptography
Feb
5
reviewed No Action Needed Sage Vs C++(with NTL) for implementing cryptosystems
Feb
5
reviewed No Action Needed Noisiest RF band for random number generation
Feb
4
reviewed Reviewed Difference between encrypting something and hashing something
Feb
4
reviewed No Action Needed Does using modulo (%) affect quality of randomness?
Feb
4
revised How fast would a polynomial time factoring algorithm compute?
edited tags
Feb
4
answered How fast would a polynomial time factoring algorithm compute?
Feb
3
comment Using Permutation polynomial to compute a MAC
@user13676: So, you compute $Mac_i$ only once (for a specific $i, k$ pair)? If so, why don't you use the simpler construction $a_i \cdot y_i + b_i \bmod p$, for secret $a_i, b_i$?