9,686 reputation
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bio website github.com/CodesInChaos
location Frankfurt, Germany
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visits member for 3 years, 1 month
seen 7 hours ago

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
Jul
2
reviewed Edit suggested edit on cfb tag wiki
Jul
2
revised cfb wiki description
edited body
Jul
2
reviewed Approve suggested edit on ofb tag wiki
Jul
2
reviewed Approve suggested edit on ofb tag wiki excerpt
Jul
2
comment Using single EC cert/keying material to derive symmetric encryption key (for storage)?
Using asymmetric encryption is rather silly if the target is yourself. It's easier and stronger to use a symmetric secret for that. Can't you derive the P521 private key and the AES key from the same master key? That'd be a strong an clean solution.
Jul
2
comment ECDH VS. DH benchmarking in JAVA
BC uses affine coordinates (at least the implementation I looked at, perhaps it offers multiple), which are really slow for most curves. Optimized implementations should be 10-20 times as fast as BC.
Jul
1
comment How much stronger is RSA-2048 compared to RSA-1024?
@woliveirajr RSA-1024 is far weaker than that. AFAIK it's currently borderline feasible to break it for state level adversaries with a few billion to spend. If it's not breakable now, 10 years from now it should be.