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1500 questions
15
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How to generate own secure elliptic curves?
I know that the algorithm used to generate the Brainpool curves and the NIST curves is published. The algorithm should be this one (RFC5639 Appendix A). From what it looks like it's rather slow to find secure parameters.
After some research I've…
SEJPM
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15
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Logjam on Elliptic Curves?
I think we're all aware of the Logjam attack.
From now on we know that re-using primes for DH is a bad idea.
But we also say that elliptic curves are safe from the attack (relying on the NFS), because it cannot be applied. I understand this.
Now in…
SEJPM
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15
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2 answers
The effect of truncated hash on entropy
Suppose I have a 128-bit random binary string (128 bits of entropy), then I hash it using SHA-256, then I take the first 128 bits of the output hash. Does the taken bit string still have (almost) 128 bits of entropy or the entropy is reduced to 64…
user40602
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Parallel Pollard's Rho: Number of distinguished points
When using the parallel version of Pollard's Rho algorithm for discrete logs, each processor performs its own random walk to find distinguished points, and reports the starting point and the distinguished point to the server. If two processors…
user13741
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How were shift amount constants in MD5 found?
The md5 specification gives a series of 4 rounds to execute over a 16-word block.
Each round has a repeating sequence of 4 shift amounts (s in [abcd k s i]) :
7, 12, 17 and 22 for the round 1
5, 9, 14 and 20 for the round 2
4, 11, 16 and 23 for the…
Antoine Catton
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Are any of the major asymmetric ciphers distinguishable (EG, RSA, ECC)?
Related to "Is it possible to derive the encryption method from encrypted text?".
Given ciphertexts generated by any of the major asymmetric ciphers (RSA, ElGamal, ECC, etc..) can these ciphertexts be distinguished from random noise? Justify why,…
Ethan Heilman
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15
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Given a 'good' basis for a lattice, how can we solve the CVP?
I'm doing a little bit of reading about lattices. I read that if we can find a 'short' basis for our given lattice, we can solve CVP and SVP very efficiently. However, the paper didn't describe an algorithm. Can anyone briefly describe an algorithm…
pg1989
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Compact digital signature for noisy data
The question asks for a signature scheme, with a public verification procedure, that is tolerant to minor alterations of the signed data during its transmission [possibly in analog form over some noisy channel], where the signature is a small…
fgrieu
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RSA cracking: The same message is sent to two different people problem
Suppose we have two people: Smith and Jones.
Smith public key is e=9, n=179 and Jones public key is e=13, n=179.
Bob sends to them a message $M$.
The encrypted message $C_s$ to Smith is 32.
The encrypted message $C_j$ to Jones is 127
I tried to…
Tomas
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Understanding how SHA-512 achieves its design goals
The Wikipedia entry on SHA-2 contains a usable pseudocode recipe. In the hope of some deeper understanding, I implemented SHA-256 and SHA-512 from it. This was helpful, but I still don't think I have joined together my understanding of how the…
Neil Slater
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2 answers
Cycle attack on RSA
I originally posted this question in the mathematics section, you can see it here.
Let $p$ and $q$ be large primes, $n=pq$ and $e : 0
Emilio Ferrucci
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2 answers
Why is there an enormous difference between SAT solvers?
SAT solvers are very important in algebraic attacks, for example walksat and minisat.
However, when solving the benchmark problems available here there is an enormous performance difference between the two - Walksat is much faster than minisat for…
ir01
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15
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3 answers
ElGamal: Multiplicative cyclic group and key generation
Here on the ElGamal wikipedia page http://en.wikipedia.org/wiki/ElGamal_encryption
Alice generates an efficient description of a multiplicative cyclic group G, of order q, with generator g.
How is this done? What are some of the properties here?
Bobby S
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If PGP and GPG both follow the OpenPGP standard, are they 100% compatible in all use cases?
If someone gives me their PGP key, can I use it with GPG, and vice versa, all the time (100% interchangeable)? Or are there times when they are not compatible, when only PGP can be used with a PGP key, and only GPG used with a GPG key?
trusktr
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Security of simple xor and s-box cipher?
What weaknesses (or strengths) do block ciphers based on only key xor and s-box have when operating in CBC mode?
A cipher's internal primitive might be a simple as this:
$C = S[M \oplus k]$, where $C$ is ciphertext, $M$ is the plaintext message, $k$…
Polynomial
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