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Mar
9
comment Shannon entropy calculation: is $H(A|R·A) = H(A)$?
@user996522: It is a group because if we consider the set of all invertible matrices and consider the operation of matrix multiplication, it fulfills all the requirements of a group; it is closed (if A and B are invertible matrices, so is $A\cdot B$), it has associativity, it has an identity element, every element has an inverse). Why being a group is important is because, for any group operation $\oplus$, if R is a uniformly and independently distributed group element, then so is $R\oplus A$, in particular, $R\oplus A$ is independent of A.
Mar
8
revised Shannon entropy calculation: is $H(A|R·A) = H(A)$?
Nit: I noticed that both matrices were singular if $n | 3$
Mar
8
revised Shannon entropy calculation: is $H(A|R·A) = H(A)$?
Amplified the last paragram a bit
Mar
8
revised Shannon entropy calculation: is $H(A|R·A) = H(A)$?
Totally misunderstood the question at first
Mar
8
answered Shannon entropy calculation: is $H(A|R·A) = H(A)$?
Mar
7
reviewed Approve suggested edit on preimage-resistance tag wiki excerpt
Mar
7
reviewed Approve suggested edit on preimage-resistance tag wiki
Mar
7
reviewed Approve suggested edit on collision-resistance tag wiki excerpt
Mar
7
reviewed Approve suggested edit on 2nd-preimage-resistance tag wiki excerpt
Mar
7
reviewed Approve suggested edit on collision-resistance tag wiki
Mar
7
reviewed Approve suggested edit on 2nd-preimage-resistance tag wiki
Mar
6
comment reverse of md5sum
@Marcos: it sounds like you're looking for a data compression method. Well, you're pretty constrained in what you can expect. If you expect the exact same preimage, well, if you have $2^N$ possible preimages, then the lengths of the hash and the seed must total at least $N$ bits long. If you expect a similar preimage, well, how well you can do is highly dependent on your definition of "similar".
Mar
6
answered reverse of md5sum
Mar
6
comment Is it safer to generate your own Diffie-Hellman primes or to use those defined in RFC 3526?
Actually, it's not actually true that "it doesn't matter what prime you use"; certain primes (say, primes where $p-1$ is smooth) are a really bad idea. In addition, it's a good to generate $p$ so that you know a large prime factor $q$, so that you can generate a generator for a subgroup that size.
Mar
6
answered Is it safer to generate your own Diffie-Hellman primes or to use those defined in RFC 3526?
Mar
6
revised Is it safer to generate your own Diffie-Hellman primes or to use those defined in RFC 3526?
edited title
Mar
3
answered What should be the size of a Diffie-Hellman private key?
Mar
2
answered What should be the size of a Diffie-Hellman private key?
Mar
2
comment Is the new preprint “An Algorithm For Factoring Integers” by Yingpu Deng and Yanbin Pan worth reading?
@Someone: the use of the additional modulo operation was certainly inspired by that use of the modulo within the AKS test; however, the current authors fail to justify why the polynomial coefficients might be interesting. The AKS test uses the fact that if the result of that is not congruent to the polynomial $x^n + a$, then $n$ is not prime; AKS says nothing about what the polynomial may be if it is not congruent, and the paper gives no justification (either theoretical or experimental) for us the expect the coefficients of that polynomial to be at all interesting.
Mar
1
answered Is the new preprint “An Algorithm For Factoring Integers” by Yingpu Deng and Yanbin Pan worth reading?