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seen Dec 16 at 17:04

Mar
14
asked What functions allow for practical indistinguishability obfuscation?
Mar
14
comment How to best mix two arbitrary/random n-bit words?
@Mok-KongShen, it would have been better if you had listed those requirements in the question. This is related to why poncho told you your question was too broad/ill-defined. Generally speaking, we tend not to like chameleon questions where someone asks a broad question without listing the requirements, then when they get an answer that answers the question-as-stated, they respond by saying "oh, that wasn't really what I was looking for, I actually had this extra requirement/goal/criterion I didn't tell you about". You can avoid that by asking narrower questions that include all the criteria.
Mar
14
asked Obfuscating point-like functions
Mar
14
comment Is this a pseudo random function (PRF)? F(k,x) = f(k,x) - f(k,x-1)
@Seth, thank you! I have fixed the error you pointed out. (I had miscounted the number of queries made by my distinguishing algorithm. I've revised my answer; should be fixed now.)
Mar
14
revised Is this a pseudo random function (PRF)? F(k,x) = f(k,x) - f(k,x-1)
Address bug from @Seth.
Mar
14
comment Traitor-tracing PRF
@RickyDemer, I realized there is a big hole in my reasoning. The argument only shows that if the PRF can be evaluated in NC1, then it's implausible that something like I described can be used for traitor tracing (since we have good reason to believe that indistinguishability obfuscation of NC1 functions is possible). However, if the PRF lives in a higher complexity class, then I think that kind of reasoning goes away, since if I understand correctly, we only know plausible constructions for obfuscation of NC1. Is that right?
Mar
14
comment Traitor-tracing PRF
Thank you! The first paragraph doesn't rule out all constructions, right, since we don't know whether indistinguishability obfuscation is possible beyond NC1? Are there any guesses/conventional wisdom about whether indistinguishability obfuscation is likely to be feasible for higher complexity classes? Your construction from a puncturable PRF is elegant... but alas, I was hoping for something efficient in practice, and with known constructions for indistinguishability obfuscation, I'm afraid this will be highly inefficient.
Mar
13
comment Traitor-tracing PRF
2. Do any other alternative approaches occur to you, for dealing with this problem? Namely, the problem that one of the participants might have their server hacked and their key stolen, and if that happens, it'd be nice if there was some way to track down which participant was responsible (which participant didn't secure their server well enough). Any creative ideas?
Mar
13
asked Traitor-tracing PRF
Mar
13
accepted Private set intersection, using a semi-trusted server
Mar
13
answered How to best mix two arbitrary/random n-bit words?
Mar
13
answered Do any one-key-of-many cryptographic schemes exist?
Mar
13
answered Linear Cryptanalysis - possible without plaintext?
Mar
13
answered Is this a pseudo random function (PRF)? F(k,x) = f(k,x) - f(k,x-1)
Mar
13
revised Is this a pseudo random function (PRF)? F(k,x) = f(k,x) - f(k,x-1)
Clean up the question. Improve the latex. Eliminate unnecessary parenthesis, avoid gratuitous \big's. Generalize and focus the question slightly.
Mar
13
answered Are there use cases where a signature itself needs to be signed?
Mar
13
awarded  Popular Question
Mar
12
awarded  rsa
Mar
12
awarded  Enlightened
Mar
11
awarded  Nice Answer