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Jun
16
revised An electronic voting system
it commitments -> its commitment
Jun
16
revised An electronic voting system
Add missing braces in TeX formulas (that are in version 3.0.1.4 of Cryptography: An Introduction)
Jun
16
revised An electronic voting system
Generalize 2; slightly simplify 4 using existing notation.
Jun
16
comment Is the HMAC construction really neccessary for a fixed length message?
I do agree that HMAC is technically superfluous when the hash is Keccak/SHA-3 (perhaps subject to padding key to a sponge step). $\;$ I do not adhere to the HMAC criticism: there are plausible defects in compression functions that do not open to attack in Merkle-Dåmgard hashes for their definition of security (collision, preimages), but open to attack in H(Key||Data) for fixed-size data (I tentatively exhibit an example in the last paragraph of my answer); HMAC masks these defects well; and I see no definitive argument that SHA-256's compression function does not have such defect.
Jun
16
revised Is the HMAC construction really neccessary for a fixed length message?
polish
Jun
16
revised An electronic voting system
get rid of extra words left from "printer than never jam", self-censored as sarcasm
Jun
16
revised Is the HMAC construction really neccessary for a fixed length message?
Adress strongly critical comment. Add some common wisdom.
Jun
16
revised An electronic voting system
Address other comment
Jun
16
revised An electronic voting system
Address other comment
Jun
15
comment Is the HMAC construction really neccessary for a fixed length message?
@eBusiness: read the last paragraph again! I exhibit a hash that is just fine (when the desired properties of the hash are collision-resistance, first preimage resistance, and second preimage resistance) according to your own "if it's not broken, then it's fine" line of thought ; but such that I effortlessly break the MAC constructions in the question according to the standard definition (that you give). $\;$ Beside, your reasoning does not invalidate my "rather be safe with a proof than sorry with an attack that surfaces" attitude.
Jun
15
revised An electronic voting system
polish
Jun
15
revised An electronic voting system
polish 2
Jun
15
revised An electronic voting system
Fix 3 and 4
Jun
15
revised An electronic voting system
Expand 3.
Jun
15
revised An electronic voting system
Try to clarify 1
Jun
15
revised An electronic voting system
Address comment
Jun
15
comment How to quickly detect incorrect password in encrypted file without compromising security?
I think that is valid only if " long, random passwords" is really long and random enough to be a key not needing stretching; e.g. has 22 letters randomly chosen among 0…9A…Za…z, giving next to 131 bits of entropy. I fear this solution (perhaps any) seriously cuts corners on security for anything a human can be expected to memorize, or routinely key-in.
Jun
15
comment Is there a scheme that allows to use RSA based challenge response protocol limited to signing only 8 bytes to create a secure signature of any data?
@Ricky Demer: if $K$ is predictable, the schemes becomes brittle, especially if $P$ is not purposely slow. In particular the adversary can (with effort about $2^{62}$ evaluations of $P$) find $m$ such that $P(K,m)$ for the predicted next $K$ has an $x_i$ of the adversary's choice, and make an existential forgery with about $2^{64}$ evaluations of $P$ and 4 queries to the broken signer with predictable $K$.
Jun
15
revised Is there a scheme that allows to use RSA based challenge response protocol limited to signing only 8 bytes to create a secure signature of any data?
polish
Jun
15
revised Is there a scheme that allows to use RSA based challenge response protocol limited to signing only 8 bytes to create a secure signature of any data?
refine the addition