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Mar
28
comment Cryptographic system with double keys with reversible order
Actually, does commutativity survive inserting either of those padding schemes? $\;$
Mar
28
revised Generating shared secret random permutation
simplified one block
Mar
28
comment Generating shared secret random permutation
In my previous comment, "a truncation" should be replaced with "the least significant bits". $\hspace{.89 in}$
Mar
28
comment Cryptographic system with double keys with reversible order
One could use OAEP+ instead of OEAP. $\;$
Mar
28
comment Is Encryption without knowing the input directly possible at all?
One could do that with generic multi-party computation. $\:$ I don't know of any more efficient solution. $\hspace{.33 in}$
Mar
28
comment Generating shared secret random permutation
(... continued) $\:$ only needs to be universal (not necessarily pairwise independent), so one can let Extract(value,seed) be a truncation of left_half_of_value + (right_half_of_value * seed) where + and * are over a finite field. $\;\;\;\;$
Mar
28
comment Generating shared secret random permutation
In my opinion, it's not, since part of the point is that the hiding property should be unconditional. $\:$ By following this proof of the Leftover Hash Lemma, one can see the (non necessarily cryptographic) hash family $\:$ (continued ...) $\;\;\;\;$
Mar
28
comment What might be assumed about a PRF if the key has been chosen?
The answers to your last and your first two questions are "no". $\hspace{2.64 in}$ I don't know the answer to your other question. $\;$
Mar
28
comment What might be assumed about a PRF if the key has been chosen?
That could not necessarily be turned into a distinguisher for $\hspace{.04 in}f$, since such an $\hspace{.04 in}f$ could be created by modifying any PRF with a large-enough key space on an exponentially-small fraction of its key space. $\hspace{.36 in}$
Mar
28
comment What might be assumed about a PRF if the key has been chosen?
securee $\mapsto$ secure $\;$
Mar
28
answered Generating shared secret random permutation
Mar
26
comment m ∈ Zn \Z*n, RSA works but not secure
Also, you have the wrong value for $\phi(p)$. $\;$
Mar
26
comment Defending hybrid encryption schemes against padding oracle attacks
@CodesInChaos : $\:$ Both the paper and the overview also use public keys where $\hspace{1.46 in}$ they should be using identities instead. $\;\;\;\;$
Mar
26
comment Defending hybrid encryption schemes against padding oracle attacks
As far as I can see, the PKAE paper simply ignores the issue that I mentioned. $\:$
Mar
26
comment Defending hybrid encryption schemes against padding oracle attacks
I don't know if that paper's scheme is "accepted as" secure, but it's not secure, since anyone who $\hspace{.23 in}$ learns the sender's private key can trivially find the plaintexts for any ciphertext created by the sender. $\hspace{.24 in}$
Mar
26
revised Security proof of FO(Fujisaki-Okamoto) hybrid encryption
spelling and grammar
Mar
25
comment Challenge–response authentication which can be done in head?
pdf.aminer.org/000/320/472/… $\;$
Mar
25
comment Distributed authentication in low trust environment
Either [[the authority's key pair has a very special form] and [the authority gives each of those entities a secret in a confidential manner] and [it's not a problem that the authority can have itself be authenticated as any of those users]] or [[the $n$ entities each generate a key-pair for public-key authentication] and [the $n$ entities each give their public key to the authority in an authentic manner] and [the authority signs the list of $\: \langle $identity , public_key$\rangle \:$ instead of $L\hspace{.02 in}$]]. $\;\;\;$
Mar
24
comment Is a random oracle controled by the challenger?
Even in those other scenarios, "the two parties do not learn anything about what the other has asked the oracle". $\:$ Those scenarios usually allow the reduction to know what the adversary asks the oracle, and sometimes allow the reduction to provide the responses instead of the oracle. $\;\;\;\;$
Mar
24
comment Is a random oracle controled by the challenger?
There are lots of instances in which the reduction "decides about ... oracle query". $\:$ However, I've never seen an instance in which the challenger "decides about ... oracle query". $\;\;\;\;$