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Jun
17
comment Choose a random number that is different from a bunch of other secret numbers
(... continued) $\:$ functionality is performed by a trusted third party then that guarantees choosing a non-clashing number and the adversary has only a half change of learning the honest party's secret number, but if your idea is repeated enough to have a sufficiently large probability of choosing a non-clashing number then the adversary has greater than a 5/6 change of learning the honest party's secret number. $\;\;\;\;$
Jun
17
comment Choose a random number that is different from a bunch of other secret numbers
I mean the "secret number between [0..x]". $\:$ I also notice that the probability I mentioned is not relevant, since an adversary would have a larger probability even if the functionality described in the opening post was performed by a trusted party. $\:$ However, for n=2 and x=3 (the simples non-trivial case), if the adversary's secret number is 2 and the honest party's secret number is either 0 or 1 and the $\:$ (continued ...) $\;\;\;\;$
Jun
17
comment Authenticated encryption without padding
Do you know of any candidate length-preserving AONTs? $\;$
Jun
17
comment Choose a random number that is different from a bunch of other secret numbers
"Proofs that participants are acting honestly is not necessary." - Do you mean adversaries are assumed to be semi-honest, or that simulatability is not required? $\;$
Jun
13
comment How to prove identity without revealing identity
No; I'm not aware of any references for this. $\:$ It's just fairly direct use of a standard signature scheme. $\hspace{.27 in}$
Jun
13
comment Algorithm accepting every passphrase to fool unlegit user
crypto.stackexchange.com/q/2272/991 $\;$
Jun
12
comment Compact digital signature for noisy data
You could only use an ECC that includes the original message in its codewords, since your setting specifies that M must be transmitted anyway. $\:$ Including sketch's_helper_data(M) in the traditional signature's input would preserve any strong unforgeability of the traditional signature scheme, insofar as that is possible in your setting. $\;\;\;\;$
Jun
12
comment Compact digital signature for noisy data
More generally, one can say that the "trivial" schemes are those in which $S$ consists of a standard signature and (possibly empty) data that together with any data recovered from the signature (which will be empty unless that scheme is with-recovery) is sufficient to recover $M$ from a noisy version of $M$, such as a not-necessarily-secure sketch. $\;$
Jun
11
revised Compact digital signature for noisy data
improved phrasing and fixed a grammar error and changed spacing
Jun
11
comment Given $n$ bits, how many “truly random” sequences/numbers can be constructed?
You might be interested in Kolmogorov complexity. $\;$
Jun
11
revised Given $n$ bits, how many “truly random” sequences/numbers can be constructed?
fixed typo, improved grammar, and changed spacing
Jun
10
revised Is ”generating transcripts that are indistinguishable from actual messages in a signature scheme” not universal forgery?
inserted link and changed spacing
Jun
9
revised How can one detect if a hash function doesn't have a full image?
fixed title's grammar and changed body's spacing
Jun
9
revised Elliptic Curve based blind signature implementation
improved grammar and changed spacing
Jun
7
comment Security of a security protocol for key exchange, using symmetric-key cryptography
@fgrieu : $\;\;\;$ Who generated $k_1$? $\:$ Who generated $k_2$? $\;\;\;\;\;\;\;$
Jun
7
revised Obfuscate an “I'll reveal if you do” function
mentioned Naor
Jun
7
comment Obfuscate an “I'll reveal if you do” function
Also, your suggestion does not satisfy "the source code ... Alice's secret", since Alice could tell Carol $s(w||q)$, so that Carol doesn't know Alice's secret but seeing $P$ would reveal Bob's secret to Carol. $\hspace{.53 in}$
Jun
7
comment Obfuscate an “I'll reveal if you do” function
What makes the obfuscation task hard is that your formalization rules out Naor commitment; I have no idea how important non-interactivity is or isn't for your motivation. $\;$
Jun
6
answered Obfuscate an “I'll reveal if you do” function
Jun
6
comment Multiplication-homomorphic schemes
You could get an upper boundary on decryption time. $\;$