CodesInChaos

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bio website github.com/CodesInChaos
location Munich, Germany
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visits member for 1 year, 10 months
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Aug
18
 reviewed Approve suggested edit on host-proof tag wiki excerpt
Aug
16
 comment Is my pseudo-random initialization vector secure?
IMO there is little reason to restrict yourself to FIPS crypto, unless you're required to be FIPS compliant.
Aug
15
 comment Common modulus attack on RSA when the 2 public exponents differ by a single bit
Are you talking about real RSA with padding, or just paddingless textbook RSA?
Aug
15
 comment Common modulus attack on RSA when the 2 public exponents differ by a single bit
I don't understand how this is supposed to work. Wouldn't the different padding prevent this attack? Or does this assume textbook RSA?
Aug
15
 comment What is the difference between these AES encryption methods
Your rewrite of the VB code still suffers from several problems I pointed out on the codeproject article. In particular your IVs are still broken, you misuse global variables and your iteration count is far too low.
Aug
13
 awarded  Nice Answer
Aug
11
 comment Why does SRP-6a use k = H(N, g) instead of the k = 3 in SRP-6?
I suspect in some implementations the server chooses the (N,g) pair freely and can choose it in a way that N is identical to some other sever, and uses a different specific g for some kind of attack. But I have no clue what that attack might be.
Aug
10
 comment What is the length of an RSA signature?
As a sidenote: While the signature size will correspond to the key size, that doesn't mean that the size of the signed message is the size of the message plus the signature size. It's possible to embed part of the message into the signature itself, making the combined size a bit smaller. This is called message recovery.
Aug
10
 comment Why does SRP-6a use k = H(N, g) instead of the k = 3 in SRP-6?
Might prevent some interactions between instances of the protocol that use different generators.
Aug
10
 comment Do MD5's weaknesses affect Oplop?
If that's the only goal of that step, then there are more straightforward ways to achieve this, that introduce less bias.
Aug
10
 comment Why can't the IV be predictable when its said it doesn't need to be a secret?
Are you talking about CBC mode?
Aug
10
 comment Is stretching hash several times basically the same as bcrypt?
bcrypt requires a constant amount of memory, and that amount is pretty small, but still a bit larger than what PBKDF2 requires.
Aug
10
 comment Cryptographic GUID?
You don't need to seen the PRNG. Pretty much any platform has a built in crypto PRNG that gets seeded by the OS. crypto.stackexchange.com/a/2657/180
Aug
9
 comment Cryptographic GUID?
Possibly a conventional V4 guid is enough, or you should pull a random number out of a crypto PRNG. But without any details I can't tell you how big the number should be. 16 bytes might be enough, but it might be possible that you need 32. Please give a bit more information on what you use it for, and what security guarantees you need.
Aug
9
 comment Do MD5's weaknesses affect Oplop?
Step 4 seems really weird. What is its purpose?
Aug
7
 comment Existing works on pre-computing ElGamal ephermal keys
You could have linked your blog for a background on what you're trying to do.
Aug
6
 comment Why is 2 the inverse of 10?
I don't understand what your question is. And how is this related to blind signatures? I never even heard of a blind ECC signature scheme.
Aug
2
 comment Is a second preimage attack on MD5 feasible?
Your use of k seems inconsistent. $ k = 2^{35} $ and putting it into the exponent in $2^{129-k}$ can't be right.
Aug
1
 comment How to jusify {e,n} is a valid RSA public key?
Do you only have the public key, or do you know the factorization of n? In your examples n is so small that factoring is trivial.
Jul
31
 comment Stream cipher malleability
You can only apply xor directly to c causing the same xor to m.
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