265 reputation
110
bio website
location
age
visits member for 1 year, 7 months
seen Sep 29 at 19:15

Kids in rectangles irritating sick urchins rattling foxes, directory.kirisurf.org lol


May
29
comment Why is plain-hash-then-encrypt not a secure MAC?
@supercat Do you not mean CFB?
May
28
comment Why is plain-hash-then-encrypt not a secure MAC?
The first attack is the type of horribly devastating attack I was expecting! Thanks!
May
28
comment Is TEA considered secure?
Oh I didn't test it. It just "felt" fast by looking at the simple code, compared to the huge spaghetti mess of lookup tables and advanced things like unusual field operations of other block ciphers like AES.
May
28
comment Why is plain-hash-then-encrypt not a secure MAC?
But I'm talking about MAC-THEN-encrypt. So unless the encryption is forgeable, the MAC should be unforgeable?
May
17
comment Is TEA considered secure?
Wow that seems impressive. Why isn't TEA more widely used then? Without lookup tables etc, things like cache timing attacks are impossible, and it's trivial to implement and super fast.
Apr
12
comment Why are collision attacks important when talking about MAC schemes?
64-bit security is kinda ridiculous nowadays though. Why aren't we seeing brute-force forgery attacks on SSH, which uses HMAC-MD5, for example? Does this imply all those AES-256-GCM things are totally pointless since they could after all be using a 64-bit key?
Apr
12
comment Why are collision attacks important when talking about MAC schemes?
Does this attack work for HMAC? I seem to recall that HMAC is secure even when the underlying hashing function is vulnerable to collision attacks much faster than birthday (i.e. MD5).
Mar
5
comment What key exchange protocols give Forward-Secrecy resisting future progress?
DHE in TLS does provide forward secrecy if properly used (no session cache etc).
Nov
12
comment Is this hand cipher any more secure than the Vigenère cipher?
Okay. "Is the key a sequence of numbers that are uniformly and independently distributed (each number is uniform of all others)?" Ideally yes, but in fact the key is just a repeated word in practice to speed up memorization. Key length: variable. We use the same key in each round.
Nov
11
comment Are there public $p$ and $q$ numbers for use in DSA?
Where? I can't find any.
Nov
1
comment Is this hand cipher any more secure than the Vigenère cipher?
The key is a repeated word, like in Vigenère.
Oct
30
comment Is this hand cipher any more secure than the Vigenère cipher?
Could you explain a bit how repetition would be bad? Unlike the Vigenère, crib-dragging and usual attacks on Vigenère don't seem to work. With multiple rounds, I am under the (false) impression that the multiple linear additions combined with the fixed permutation give a random-to-the-human-eye, nonperiodic, keystream.
Oct
30
comment Is this hand cipher any more secure than the Vigenère cipher?
That is in fact what I had in mind when I mentioned "very slow" hand ciphers...
Oct
30
comment OFB or CTR mode without an IV
Theoretically the maximum size is 65536 bytes, but usually libraries send records with size 4096 bytes and less.
Oct
27
comment How does SSL secure the initial handshake?
So in the real world, as long as the servers are configured not to support weak ciphers, the Finished messages don't really matter?
Oct
27
comment How does SSL secure the initial handshake?
What if the attacker forces the client and server to negotiate the NULL cipher?
Oct
27
comment OFB or CTR mode without an IV
I'm assuming that the question was more like is it possible to use CTR or OFB mode securely without transmitting IV. I.e. for instance, start at all zeroes IV/counter and increment the counter for each message.. You seem to be the only person to have understood my question :)
Oct
27
comment How does SSL secure the initial handshake?
Yes, I mean TLS. SSL 3.0 isn't severely deprecated, though. I think it is still widely used. SSL 2.0 is the badly insecure one.
Oct
27
comment OFB or CTR mode without an IV
Why does CBC mode require new IVs for each ~kilobyte sized record in the same connection though?
Oct
27
comment Random session key + predictable IV
One key is used for one side of a connection. The key initialization function is called once for each side.