Thomas Pornin

19,082 reputation

13571

bio	website	bolet.org/~pornin
	location	Quebec City, Canada
	age	37
visits	member for	1 year, 10 months
	seen	May 17 at 22:22
stats	profile views	284

Cryptographer, programmer in several languages (C, Java, several assemblies, Pascal, Forth...). I also have a life.

	19,082 reputation	bio	website	bolet.org/~pornin	visits	member for	1 year, 10 months
13571 badges		location	Quebec City, Canada		seen	May 17 at 22:22

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Dec 30	answered	Efficient Symmetric Mutual Entity Authentication Protocol
Dec 22	awarded	Good Answer
Dec 7	answered	Are really, really long passwords any securer than short ones?
Dec 7	reviewed	Approve suggested edit on RSA 4096 bit key benchmark
Nov 30	comment	Exhausting the entropy of a hash function There are details. There are also online dictionary attacks, which are performed against the live target server, without knowing the hash value. Specific preimage resistance of the hash function is irrelevant for that. But if the attacker knows the hash value, then yes, there is no need, even academic, to push the password entropy beyond the preimage resistance of the hash function.
Nov 30	answered	Exhausting the entropy of a hash function
Nov 29	answered	Constructing RSA private key, given public key
Nov 29	answered	What cipher mode is suitable for independantly decryptable short messages?
Nov 24	answered	Does a trace of SSL packets provide a proof of data authenticity?
Nov 23	comment	Mapping between subgroups and the integers $q$ is a prime so it is odd ($2$ is the only even prime). Therefore $q = 2k+1$ for some integer $k$. So, $p = 2q+1 = 4k+3$, which means that $p = 3 \mod 4$. Whe computing modulo a prime $p$ which is equal to 3 modulo 4, $-1$ is not a quadratic residue, so $x$ and $-x$ cannot be both quadratic residues (but one of them necessarily is).
Nov 20	answered	Can I use my random IV (for AES) as a salt for PBKDF2?
Nov 20	answered	Is there an authenticated encryption scheme where the recipient can attribute the message to a single sender?
Nov 17	answered	Implementing AES in C++: 4x4 Array of unint8_t, or 4x1 array of uint32_t?
Nov 15	awarded	Good Answer
Nov 11	answered	Montgomery Exponentiation - selecting input value R for a given BigInteger
Nov 7	answered	Constructing a block-cipher from a hash function
Oct 29	reviewed	Approve suggested edit on Does chaining random number generators lead to loss of randomness?
Oct 29	reviewed	Approve suggested edit on skein tag wiki excerpt
Oct 29	reviewed	Approve suggested edit on sha-3-competition tag wiki excerpt
Oct 29	reviewed	Approve suggested edit on