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bio website github.com/CodesInChaos
location Frankfurt, Germany
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visits member for 3 years, 3 months
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Feb
12
comment Measuring Shannon's diffusion
Measuring the number of rounds a full diffusion takes is common.
Feb
12
reviewed Approve suggested edit on Why does the SRP-6 calculation of B include a multiplier k = 3?
Feb
12
comment Why does the SRP-6 calculation of B include a multiplier k = 3?
Are you talking about SRP-6 or SRP-6a? It seems like 6a doesn't use k=3 like you claim.
Feb
12
comment Why does the SRP-6 calculation of B include a multiplier k = 3?
related: Why does SRP-6a use k = H(N, g) instead of the k = 3 in SRP-6?
Feb
11
comment PBKDF2 for key diversification
If the master key has high entropy, I'd prefer HKDF over PBKDF2
Feb
11
comment brute force attack on KDF vs KEY
@hunter 20 bits fits a million iterations of PBKDF2, and scrypt is a bit costlier due to the high RAM requirement, so I guessed 40. I was too lazy to do any actual math.
Feb
10
comment Can we replace the XOR operation in DES with some other operation?
What do you want to achieve with that change? There are many ways to change DES, but most of them are not a good idea.
Feb
10
comment Is AES reducible to an NP-complete problem?
We know no such reductions for any cryptosystem we use in practice. Not AES, nor RSA. Such reduction isn't too useful in the first place, since complexity classes talk about asymptotic cost, whereas we want to know if a certain concrete key-size is secure.
Feb
10
revised ElGamal signature: Forging a signature of a specific form
added 3 characters in body; edited title
Feb
10
comment Request for 1024-bit primes $p$ , subgroup $q$ and subgroup generator $g$
@Barack You should merge your accounts. See crypto.stackexchange.com/help/user-merge
Feb
10
reviewed Approve suggested edit on Request for 1024-bit primes $p$ , subgroup $q$ and subgroup generator $g$
Feb
9
comment brute force attack on KDF vs KEY
You can increase the security level by perhaps 20-40 bits using a slow KDF. So to reach 256 bits, the suer would still need a really strong password.
Feb
9
comment How to bring little changes in DES algorithm
First you need to figure out what drawbacks you mean? The small key? The small block-size? The bad software performance?
Feb
8
revised What is 'security margin'?
added 6 characters in body
Feb
8
comment Hashing a password with SHA256 on the client then bcrypt on the server
Do it the other way round. Bcrypt on the client, and SHA-256 on the server
Feb
8
comment Request for 1024-bit primes $p$ , subgroup $q$ and subgroup generator $g$
What do you want to use those for? The requirements for those differ subtly with use. For example ElGamal signatures need a large generator. For most uses I'd just look up a set of group parameters in a DSA or DH standard.
Feb
8
comment AES implementation in java that allows key of 320-bit length
cross-posted
Feb
8
comment AES implementation in java that allows key of 320-bit length
Why do you want 320 bit keys? 256 is already more than enough. If it's because your key material is that large, just hash it with SHA-256 to get a 256 bit key.
Feb
8
answered What is 'security margin'?
Feb
7
comment Source for examples with broken cryptography
That attack of A5/3 is a related key attack. So unless you're using a really weird protocol, it's not relevant in practice. Just like related key attacks against AES are pretty irrelevant.