« first day (3967 days earlier)      last day (697 days later) » 

Crypto HNQ
Crypto HNQ
2:38 AM
1
Q: Elliptic Curve - distinguish between two points after multiplication

Robert MIf $P$ and $Q$ are two points on an elliptic curve of large prime order, given $P, Q$, and a point $R$ which is either (a) $nP$ or (b) $nQ$, is it possible to determine if $R$ is of form (a) or form (b)? Here $n$ is a secret.

elliptic-curves
 
 
2 hours later…
Crypto HNQ
Crypto HNQ
5:07 AM
2
Q: Skipping first outputs of the stream cipher

TomI remember reading somewhere that sometimes in some stream ciphers it is necessary to skip the first values they produce. I can't find any information on this right now. But it seems to make sense. Just as a hash function needs to do many rounds before it returns a random result, the CSPRNG needs...

stream-cipher
 
 
13 hours later…
Crypto HNQ
Crypto HNQ
6:19 PM
1
Q: Non-committing authenticated encryption schemes vs committing authenticated encryption schemes

WilliI'm told that TLS 1.3 supports only non-committing authenticated encryption schemes. What is a non-committing authenticated encryption scheme? What is the difference between committing and non-committing authenticated encryption schemes? What are the pros and cons?

tls authenticated-encryption commitments
 
 
4 hours later…
Squeamish Ossifrage
Squeamish Ossifrage
10:35 PM
3
A: Skipping first outputs of the stream cipher

Gilles 'SO- stop being evil' I remember reading somewhere that sometimes in some stream ciphers it is necessary to skip the first values they produce. Not some stream ciphers, but one specific cipher: RC4. RC4 is from an earlier era when cryptographic primitives did not receive a lot of scrutiny – in fact, it was originall...

> The main weakness was that a bias in the beginning of the keystream. RC4 was popular at the time the bias was first discovered, and a countermeasure was to discard the first few bytes.
This is misleading, bordering on false. RC4 was broken within 24 hours of its publication, loooooong before it became popular.
 

« first day (3967 days earlier)      last day (697 days later) »