Reputation
4,249
Next tag badge:
47/100 score
29/20 answers
Badges
1 6 21
Newest
 Yearling
Impact
~40k people reached

May
15
comment Authenticate a short message with redundant encryption instead of using a MAC?
SHA1(MasterKey) has a different length from AES keys. $\;$
May
15
revised How can one improve Rijndael's with more efficient SBoxes?
fixed title's grammar
May
15
comment How do we guarantee plaintext is coprime in RSA?
@fkraiem : $\:$ In fact, it's sufficient for $k$'s congruence to be modulo $\operatorname{L}\hspace{-0.03 in}\operatorname{cm}(\hspace{.04 in}p\hspace{-0.04 in}-\hspace{-0.05 in}1,\hspace{-0.02 in}q\hspace{-0.04 in}-\hspace{-0.05 in}1)$. $\;\;\;\;$
May
15
answered Ephemeral Diffie-Hellman in a symmetric crypto context
May
14
comment Why cant Public Key Encryption be perfectly secure?
James did not say that he wants the definition of soundness you're apparently referring to. $\hspace{.82 in}$ Such a PKE scheme cannot be sender-deniable. $\;$
May
14
comment Why cant Public Key Encryption be perfectly secure?
This only works if an honestly generated public key has probability greater than half of being such that different messages cannot result in the same ciphertext. $\;$
May
11
comment How are messages from server secured when using SSL certificate
The message level encryption uses the symmetric key(s). $\;$
May
11
comment How are messages from server secured when using SSL certificate
What you're missing is that message is a symmetric key. $\;$
May
11
comment Second generator for secp256k1 curve
"that know one" $\: \mapsto \:$ "that no one" $\;\;\;\;$
May
8
comment Is it hard to recover $p$ from $k \phi(p)$?
No. ${}{}{}{}\;$
May
7
comment Why does Diffie-Hellman need be a cyclic group?
One could work with a commutative magma action instead of a semigroup. $\;$
May
7
comment Mutual verification of shared secret
I now think the assumption I mentioned would only help in the random oracle model, in which case the "uniformly" part would actually be irrelevant. $\:$ The relation is to your opening paragraph, rather than the example you gave or the comments to my answer. $\;\;\;\;$
May
7
comment Mutual verification of shared secret
@codebeard : $\:$ Do you also want to assume that their inputs are uniformly distributed, $\hspace{1.15 in}$ and either identical or each unguessable given the other? $\;\;\;\;$
May
7
comment Why does spiped use both nonces and ephemeral keys?
That's fine. $\;$
May
7
comment Why does spiped use both nonces and ephemeral keys?
Yes. ${}{}{}\;$
May
7
comment Why does spiped use both nonces and ephemeral keys?
The attacker doesn't "now produce a packet with a valid HMAC tag". $\;$
May
7
comment Why does spiped use both nonces and ephemeral keys?
The attacker would just send the same group_element || MAC_tag to the party that message $\hspace{.26 in}$ was sent to before, even though that "party will end up computing a different shared secret every time." $\hspace{.15 in}$
May
7
answered Why does spiped use both nonces and ephemeral keys?
May
7
comment Mutual verification of shared secret
@codebeard : $\;\;\;\;\;\;\;$ No, I mean Bob. $\;\;\;$ The "naive approach" you gave would let Bob try however many guesses his computing power lets him evaluate $\: h\circ h \:$ on, with high accuracy. $\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;$
May
7
comment How is HMAC(message,key) more secure than Hash(key1+message+key2)
It may be better to switch the order of subtraction, so that storing $\:b-1\:$ as a constant could reduce the necessary number of arithmetic operations by one. $\;\;\;\;$