143,223 reputation
22290491
bio website bolet.org/~pornin
location Quebec City, Canada
age 39
visits member for 3 years, 9 months
seen 8 hours ago

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


2d
awarded  Good Answer
Sep
18
awarded  Good Answer
Sep
17
awarded  Enlightened
Sep
13
comment How to securely hash passwords?
There is an attack against scrypt that can help an attacker up to a factor of 4, which is not critical. scrypt can still be considered to fare at least as good as bcrypt, and substantially better when the attacker has FPGA. It is still harder to configure and using it for a busy server with high peak loads requires some care. So far, PHC has a few candidate functions which try to do "memory hardness" like scrypt, but are arguably better at it.
Sep
11
awarded  Necromancer
Sep
9
comment How does SSL/TLS work?
The session ID is returned in the ServerHello message, always. The client may send in the ClientHello the ID for a session that it wants to resume; the server always respond in the ServerHello with the ID for the session that will be used. If the client sent a non-empty ID and the server responds with the same non-empty ID, then this is a session resumption; otherwise, this is a new session, identified by the ID that the server just sent (and the client may use that ID in its next ClientHello).
Sep
8
awarded  Nice Answer
Sep
6
comment What is 'TLS version intolerance'
The "98" is arbitrary; the encoding is binary, not decimal. Version "x.y" is encoded as two bytes of value 2+x and 1+y, respectively (i.e. TLS 1.0 is encoded as 0x03 0x01), so the cutoff would be at 1.254 -> 2.0 (or even 2.-1 for 0x04 0x00). Point is that some implementation will accept 0x03 0xYY for any YY beyond 03, but reject 0x04 0xZZ.
Sep
5
awarded  Good Answer
Sep
5
answered If TLS compression is not supported is a site still vulnerable to attacks such as BREACH?
Sep
5
comment SSH key-type, rsa, dsa, ecdsa, are there easy answers for which to choose when?
No. In fact, everything that was revealed in that affair only confirms what was already known, i.e. that when big governmental agencies spy on people, then don't do it by trying to break cryptography upfront; they rather work around it. In the SSH case, they would collect metadata (this client machine connects to that server) that is not protected by the SSH protocol, regardless of the server key algorithm or size.
Sep
5
awarded  Enlightened
Sep
5
awarded  Nice Answer
Sep
4
answered What is 'TLS version intolerance'
Sep
4
awarded  Good Answer
Sep
2
awarded  Guru
Sep
1
awarded  Nice Answer
Aug
29
awarded  Enlightened
Aug
29
awarded  Nice Answer
Aug
29
awarded  Nice Answer