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bio website github.com/CodesInChaos
location Frankfurt, Germany
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visits member for 3 years, 3 months
seen 11 hours ago

Dec
4
comment In RSA encryption, does the value of e need to be random?
some combinations of $e$ and $n$ don't work. $e$ and φ(n) must be coprime.
Dec
3
comment Is Convergent Encryption really secure?
Tahoe LAFS uses convergent encryption with AES in CTR mode. So your last sentence is clearly wrong. It simply derives both key and IV deterministically from the hash of the plaintext (and a convergence secret)
Dec
2
comment Is Convergent Encryption really secure?
If your encryption primitive has weak keys it sucks, use a better primitive. It's also easy to implement convergent encryption rejects certain keys. This is not a valid problem in practice.
Dec
2
comment SSL Key Exchange
The standard technique is trusting the installed software(in particular the installed root certificates) and CAs which sign a certificate only for the legitimate owner of a domain.
Dec
2
comment SSL Key Exchange
"Assuming the messages can be read by a third party, but not manipulated." We generally avoid that assumption, since usually being in a position to read messages allows you to manipulate them as well.
Dec
2
comment SSL Key Exchange
I can't say if a method is secure unless I get a clear description of it. The purpose of ephermeral key-exchange is to provide forward secrecy. So when you lose your long term private key, an attacker can't decrypt recorded connections.
Dec
2
comment SSL Key Exchange
Generating one is easy in principle, but apart from client authentication(rarely used) and ephemeral key-change(for forward privacy) it's not that useful. IMO one should always use ECDHE where neither side creates the session key, and instead it's the result of a key-exchange operation.
Dec
2
comment SSL Key Exchange
How would that work? You can't encrypt the session key with the client's public key, because it usually doesn't have one. There are different ways to avoid replay problems, using a nonce on both sides that's mixed into the session key is just one easy solution.
Dec
2
answered SSL Key Exchange
Dec
2
comment Ensuring integrity of a client side script
Impossible. It's just another variant of the DRM problem, where you don't trust the computer you're running on. Best you can do is throwing lots of obfuscation at it, and then pray that nobody bothers to break it.
Dec
2
comment Webcam random number generator
@D.W. Sensor noise is a nice source of entropy. Obviously you still need to feed it into a standard PRNG.
Dec
2
reviewed Approve suggested edit on What's a good P to use in ElGamal key generation?
Dec
1
comment Weakness in using only one RSA key pair for two-way communication?
Your scheme is essentially symmetrical, so why would you use RSA over AES?
Nov
30
answered What's a good P to use in ElGamal key generation?
Nov
30
comment What's a good P to use in ElGamal key generation?
Any reason why you want to use ElGamal over Diffie-Hellman, DSA or Schnorr signatures? Are you talking about ElGamal encryption or ElGamal signatures?
Nov
29
reviewed Edit suggested edit on AES timing attacks
Nov
29
revised AES timing attacks
made link work + title
Nov
29
reviewed Approve suggested edit on
Nov
29
comment Message authentication codes construction
Please don't cross-post
Nov
29
revised Message authentication codes construction
deleted 153 characters in body