Ricky Demer
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 Mar 15 comment What is Deterministic Authenticated Encryption? In layman's terms, it's exactly what it sounds like. ​ It's supposed to provide $\hspace{1.79 in}$ the deterministic version of confidentiality. ​ ​ ​ ​ Mar 15 comment Is there an asymmetric algorithm that can perform double encryption? Well, one could use RSA permutations with non-decreasing moduli. ​ ​ Mar 15 comment Is there an asymmetric algorithm that can perform double encryption? I just edited my answer to address that. ​ ​ Mar 15 revised Is there an asymmetric algorithm that can perform double encryption? addressed symmetric case Mar 15 answered Is there an asymmetric algorithm that can perform double encryption? Mar 14 answered Format preserving encryption Mar 14 awarded Informed Mar 14 comment Format preserving encryption honey encryption, low-bandwith channels, sampling distinct integers from a range ​ ​ Mar 14 comment Format preserving encryption Yes. ​ ​ ​ ​ ​ ​ Mar 13 comment Weak and Strong Collision Resistance, again @kodlu : ​ en.wikipedia.org/wiki/Non_sequitur_(logic) ​ ​ ​ ​ Mar 13 comment SHA-3 padding clarifications Do you know why the padding ends with 1? ​ (rather than just being 10*) ​ ​ ​ ​ Mar 12 comment Why haven't we proven many things computationally secure yet? CPA can be replaced with CCA. ​ ​ Mar 12 comment What is perfect collision-resistence in probability terms? How is $\mathcal{Z}$ relevant? ​ ​ Mar 11 answered Why haven't we proven many things computationally secure yet? Mar 11 comment Is it possible to brute force a single smaller variable in $\operatorname{HMAC-SHA512}(k, a\ ||\ b\ ||\ c\ ||\ d)$? Another option is using a prefix-free code. ​ ​ Mar 11 comment Is it possible to brute force a single smaller variable in $\operatorname{HMAC-SHA512}(k, a\ ||\ b\ ||\ c\ ||\ d)$? It works fine in your case, since a,b,c,d are all fixed length (even all-but-one of them being fixed-length would suffice), but in general, concatenation does not necessarily suffice, since for example ​ ​ ​ 01 || 0 ​ = ​ 0 || 10 ​ ​ . ​ ​ ​ ​ ​ ​ ​ ​ Mar 9 comment Using One Time Pad with a block cypher By its list view, if I'm interpreting this correctly, the the possibilities for 2-bit blocks are all "equivalent" to the trivial ones (bitwise and mod 4), but there are lots of inequivalent possibilities for 3-bit blocks. ​ ​ Mar 7 comment Prove that the given scheme is CPA secure or not PRPs with small domain are not PRFs. ​ ​ ​ I think the flag bad should be set if and only if the random function is called more than once on ​ r || challenge_plaintext . ​ ​ ​ ​ ​ ​ ​ ​ Mar 7 comment Prove that the given scheme is CPA secure or not Oh, yeah, I missed that part. ​ I think the idea will be showing that PRPs with large domain are also PRFs. ​ ​ ​ ​ Mar 6 answered Merkle signature scheme