CodesInChaos

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bio	website	github.com/CodesInChaos
	location	Munich, Germany
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Jabber/XMPP: CodeInChaos@jabber.ccc.de
IRC: CodesInChaos on freenode
Email: My nick on gmail
Blog: codesinchaos.wordpress.com
GitHub: github.com/CodesInChaos
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	5,964 reputation	bio	website	github.com/CodesInChaos	visits	member for	1 year, 10 months
1927 badges		location	Munich, Germany		seen	4 hours ago

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Nov 16	comment	Why does OAEP have 2 rounds with 2 random oracles? This is essentially an all-or-nothing transform.
Nov 16	comment	Is it safer to encrypt twice with RSA? Not sure if you can call $(m^{e_1})^{e_2}$ encrypting twice since that only works with textbook RSA. With real RSA, you'd add padding before each encryption, making the intermediate ciphertext too large for a single exponentiation of the second encryption.
Nov 16	comment	Is it safer to encrypt twice with RSA? If you know $e$, $d$ and $n$ you can efficiently factor $n$ to obtain $p$ and $q$. Once you know $p$ and $q$ obtaining $d_2$ from $e_2$ is trivial. See Can two different pairs of RSA key have the same modulus?
Nov 16	comment	AES key padding @mikeazo I avoid constructions with a non uniform key in most situations. I prefer some kind of hashing or KDF step in between.
Nov 15	answered	AES key padding
Nov 15	revised	AES key padding deleted 3 characters in body
Nov 13	comment	ZeroBin security Perhaps the read-cap gets only distributed to a few select targets per email or chat.
Nov 13	comment	ZeroBin security What's your question? You only made a statement.
Nov 13	comment	Montgomery Exponentiation - selecting input value R for a given BigInteger (I hope this is just for fun. You'll have huge side channels with such an implementation)
Nov 12	comment	How does a client verify a server certificate? My blog doesn't contain anything on SSL. You should read How does SSL work? on security.SE. If you want to contact me, the info is in my profile.
Nov 12	comment	How does a client verify a server certificate? "client generates a random number, encrypts it with my public key" That's only true for plain RSA suites. Stronger suites use a different algorithm with temporary asymmetric keys that get signed with the long term key.
Nov 11	reviewed	Approve suggested edit on Difference between stream cipher and block cipher
Nov 9	comment	Is 512-bit RSA still safe for signature generation? And a how-to
Nov 9	comment	Is 512-bit RSA still safe for signature generation? Breaking 512 bit RSA seems to cost around 100$ ATM.
Nov 9	comment	cracking WINRAR encryption method(AES) using brute force Why do you claim Winrar's encryption is unbreakable? Just like every other password based encryption, it's only as strong as the password. They use a decent iteration count in their KDF(~250k), but their actual encryption is clearly suboptimal(ECB mode).
Nov 8	comment	Reg:key Agreement Protocol Do you actually want to secure data with it, or is this just an exercise? If you actually want security, then you should use an existing library instead of implementing it yourself.
Nov 7	comment	Advantage of AES(Rijndael) over Twofish and Serpent Might want to mention timing attacks and AES-NI
Nov 7	comment	Advantage of AES(Rijndael) over Twofish and Serpent Related reading: So you want to use an alternative cipher - Matthew Green's blog
Nov 7	answered	Slow hash algorithm that does not require salt?
Nov 7	answered	Pseudo-random Number generation for Passwords