9,526 reputation
12347
bio website github.com/CodesInChaos
location Frankfurt, Germany
age
visits member for 3 years, 1 month
seen 8 mins ago

Jul
5
comment DSA, RSA, ECDSA etc - which one is cheapest for signing?
ECDSA is rather cheap. Personally I'd go with Ed25519 for signatures, which has a easily available high performance implementations.
Jul
5
comment What is the recommended replacement for MD5?
AFAIK SHA-3 isn't specified yet, if you want to use it now you need to use a Keccak variant that'll be slightly different from the final SHA-3. So I recommend waiting until the SHA-3 standard is actually published.
Jul
5
reviewed Approve suggested edit on Guarding against cryptanalytic breakthroughs: combining multiple hash functions
Jul
4
comment Generate a new public/private key pair for each new message?
@Christian The problems with this one is that key management becomes annoying. That's why protocols with a live connection like SSL or OTR can use similar techniques, for example to obtain forward-secrecy. For store and forward protocols like email it's far more annoying. For example how would you support receiving mails on multiple devices?
Jul
4
comment Generate a new public/private key pair for each new message?
@Shaga It's only hard if you only consider cryptographic attacks. Attackers gaining access to the private key by compromising an endpoint is a practical threat. This includes trojans, police raids, subpoenas,...
Jul
4
reviewed Approve suggested edit on constructing QR-like one way function
Jul
4
comment Fast Salsa20 in java?
Do you have a link to an optimized Salsa20 implementation?
Jul
4
comment Construct a random permutation from a random function?
In the current form it's a purely theoretical problem. If this is based on a practical problem, then my impression is that your approach is misguided, i.e. that you suffer from the XY problem.
Jul
4
reviewed Approve suggested edit on length-extension tag wiki
Jul
4
reviewed Approve suggested edit on padding-oracle tag wiki excerpt
Jul
4
reviewed Approve suggested edit on padding-oracle tag wiki
Jul
4
reviewed Reject suggested edit on length-extension tag wiki
Jul
4
reviewed Reject suggested edit on length-extension tag wiki excerpt
Jul
4
comment Hash Family Example
Sounds like you want a keyed hash. A common choice is HMAC-SHA-2(k, m). With SHA-3 it's even easier since it's not subject to length extensions, so SHA-3(k||m) works.
Jul
3
reviewed Approve suggested edit on How to find generator $g$ in a cyclic group?
Jul
3
comment Construct a random permutation from a random function?
If this is a practical problem, you should take a step back and describe your actual requirements.
Jul
3
comment Construct a random permutation from a random function?
Since a truncation of a PRF is still a PRF, you can trivially use the above construction where you truncate the PRF to N/2.
Jul
2
reviewed Approve suggested edit on cbc-mac tag wiki
Jul
2
reviewed Approve suggested edit on cbc-mac tag wiki excerpt
Jul
2
reviewed Approve suggested edit on cfb tag wiki excerpt