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age 44
visits member for 2 years, 11 months
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programs in C and Perl, mostly

Jun
16
awarded  Critic
Jun
12
comment How to choose the appropriate public (i, m) and private (j, m) keys?
Mostly people choose some $i$ that has no divisors in common with $\phi(m)$ (in this case 64), and this is easy to check (Euclid's algorithm) and then $j$ is its inverse (also found by the (extended) Euclidean algorithm). We can choose any such $i$ (and keep its inverse $j$ secret). Often $i=3$ or $i=2^{16}+1$ is chosen, but we need not do that. It's the same for bigger numbers.
Jun
12
revised How to choose the appropriate public (i, m) and private (j, m) keys?
expansion.
Jun
12
comment How to choose the appropriate public (i, m) and private (j, m) keys?
We can use either one, both work. Either $(p-1)(q-1)$ or the least common multiple of $(p-1)$ and $q-1$. And you just pick any $i$ that has an inverse $j$ modulo that number.
Jun
12
answered How to choose the appropriate public (i, m) and private (j, m) keys?
Jun
9
comment How does Scrypt use Salsa?
The compression is as seen from the point of view of the message, not of the state. The state stays the same size, and the message bytes are all used, as many as we have. We output the state at the end, which is often a lot shorter than the message, which has been mixed into the state iteratively.
Jun
9
comment How does Scrypt use Salsa?
Study the SHA-1 spec. The work is done mostly in a function that transforms the 20 byte state to another 20 byte state with the message as "key" (this component is the blockcipher SHACAL). So at the core of SHA-1 is a block transform as well, and this is the one used. The whole hash is the function with the fixed input state, and message padding added, plus the iterative application of this transform for successive blocks.
Jun
8
comment Is symmetric key encrypted with server's public key secure
If they already share a secret password, cannot they base their scheme on that? Like SRP? Why bother with the RSA?
Jun
8
comment Is symmetric key encrypted with server's public key secure
What identification scheme? Based on the supposed shared secret that they think they have? Then how does Bob distinguish Mallory from Alice, if the former does an active attack on both phases?
Jun
8
comment How does Scrypt use Salsa?
It is, but it is not a hash in the traditional sense. It's a cryptographic mixing function, normally used as a component in the stream cipher Salsa20. The use in scrypt is different from its use in the stream cipher, and the author in the scrypt paper shortly discusses that too.
Jun
8
revised How does Scrypt use Salsa?
added 258 characters in body
Jun
8
answered How does Scrypt use Salsa?
Jun
8
answered What does “message schedule” mean in SHA-256?
Jun
5
comment IV Security Clarification
From what I see online (I don't know the implementation, but let's trust Microsoft here), yes, that is the right function to use. E.g. stackoverflow.com/a/2530643/342544
Jun
5
comment IV Security Clarification
Yes, I would say that. You use good sources of randomness I suppose?
Jun
5
answered IV Security Clarification
Mar
22
answered reduces the coefficients of a modulo 3 on NTRU
Mar
12
comment computing inverses in truncated polynomial rings manually for NTRU encryption
Pretty sure, if I have more time, I'll try to compute it too, by hand, of course.
Mar
12
comment computing inverses in truncated polynomial rings manually for NTRU encryption
@SuniaRaharja yes, the polynomial $x$ (bad choice of notation) is indeed the inverse, and then you need to reduce mod 11. If all is well, you shouls get $a^{-1}$ or an equivalent (mod 11) polynomial.
Mar
11
comment computing inverses in truncated polynomial rings manually for NTRU encryption
Basically, using Extended Euclidean, do the inverse computation of $a$ in $\mathbb{Z}[X]$, doing the gcd with $X^7 - 1$, and reduce the coefficients modulo 11 afterwards.