diff -r 6c7996b6b471 -r ddac52c0014c handouts/ho06.tex --- a/handouts/ho06.tex Sat Jan 03 23:14:47 2015 +0000 +++ b/handouts/ho06.tex Sun Mar 01 00:11:13 2015 +0000 @@ -47,7 +47,7 @@ \end{quote} \noindent -You could go on to look up the definition of the third +You could go on looking up the definition of the third non-article in this definition and so on. But let us assume you agreed with Bob to stop after three iterations with the third non-article word in the last definition, that is @@ -80,21 +80,21 @@ were barred from publishing their results used also a hash to prove they did the work and (presumably) managed to get into cars without a key; see Figure~\ref{paper}. This is very -similar to the method about crosswords: They like to prove -that they did the work, but not giving out the ``solution''. -But this also shows what the problem with such a method is: -yes, we can hide the secret temporarily, but if somebody else -wants to verify it, then the secret has to be made public. Bob -needs to know that \textit{folio} is the solution before he -can verify the claim that somebody else had the solution -first. Similarly with the paper: we need to wait until the -authors are finally allowed to publish their findings in order -to verify the hash. This might happen at some point, but -equally it might never happen (what for example happens if the -authors lose their copy of the paper because of a disk -failure?). Zero-knowledge proofs, in contrast, can be -immediately checked, even if the secret is not public yet -and perhaps never will be. +similar to the method above about crosswords: They like to +prove that they did the work, but not giving out the +``solution''. But this also shows what the problem with such a +method is: yes, we can hide the secret temporarily, but if +somebody else wants to verify it, then the secret has to be +made public. Bob needs to know that \textit{folio} is the +solution before he can verify the claim of Alice that she had +the solution first. Similarly with the car-crypto paper: we +need to wait until the authors are finally allowed to publish +their findings in order to verify the hash. This might happen +at some point, but equally it might never happen (what for +example happens if the authors lose their copy of the paper +because of a disk failure?). Zero-knowledge proofs, in +contrast, can be immediately checked, even if the secret is +not public yet and perhaps never will be. \begin{figure} \begin{center} @@ -331,7 +331,7 @@ If somehow Alice can find out before she committed to $H_i$, she can cheat. For this assume Alice does \emph{not} know an isomorphism between $G_1$ and $G_2$. If she knows which -isomorphism Bob will ask for she can craft $H$ ins such a way +isomorphism Bob will ask for she can craft $H$ in such a way that it is isomorphism with either $G_1$ or $G_2$ (but it cannot with both). Then in each case she would send Bob a correct answer and he would come to the conclusion that @@ -407,6 +407,8 @@ \end{document} +http://blog.cryptographyengineering.com/2014/11/zero-knowledge-proofs-illustrated-primer.html + http://btravers.weebly.com/uploads/6/7/2/9/6729909/zero_knowledge_technique.pdf http://zk-ssh.cms.ac/docs/Zero_Knowledge_Prinzipien.pdf http://www.wisdom.weizmann.ac.il/~oded/PS/zk-tut02v4.ps