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May
30
comment Is this adaptation of one-time-pad still secure?
Yes, since you would be using y twice. $\;$
May
29
answered Constructing set membership proof for private set
May
29
comment Fast PKI for embedded device
... and the remainders of $n$ modulo those moduli should be included alongside the public key. $\hspace{.74 in}$
May
29
comment Fast PKI for embedded device
One could instead include [the quotients required to perform reduction for the publicly known moduli that will be used to verify $\;\; f\hspace{-0.06 in}\cdot \hspace{-0.04 in}h+n\hspace{-0.04 in}\cdot \hspace{-0.04 in}t \: = \: s^{\hspace{.02 in}2} \;\;$ (see "Verifying signatures" on page 3)] along with (the rest of) the signature. $\;\;\;\;\;$ In that case, those publicly known moduli should be selected to support fast multiplication, rather than fast division, ... $\;\;\;\;\;\;\;\;\;\;$
May
28
comment What is the right notion of security to use for file encryption?
Yes. ${}{}{}\;$
May
28
revised What is the right notion of security to use for file encryption?
provided a more complete reference
May
28
answered What is the right notion of security to use for file encryption?
May
28
comment Fast PKI for embedded device
I saw [the restriction (involving $\overline{\pi}$) on the moduli] and the heuristic primality test (rather than Bernstein's zero-error test or Miller-Rabin). $\:$ I haven't yet looked further into the paper you linked to. $\;\;\;\;$
May
28
comment Fast PKI for embedded device
The efficiency of these can be greatly improved if the signer and verifier(s) stay in sync (i.e., verify messages in the same order as they were signed). $\;$
May
28
comment Fast PKI for embedded device
@MaartenBodewes : $\:$ Sections 4 and 7 of the paper linked to at the top of my answer each describe a reason why the scheme linked to in this answer is fast. $\;\;\;\;$
May
28
comment Fast PKI for embedded device
Note that at least some of that paper is trading off correctness and security for things other than verification speed. $\:$ In the other direction, depending on how long those devices might remain in use, it may be worth using a 1280-bit modulus instead of a 1536-bit modulus. $\:$ (With that sort of idea in mind, it might even be worth having a dedicated public key for signing each device's files, to reduce the effect that factoring one of their moduli would have.) $\;\;\;\;$
May
28
comment Fast PKI for embedded device
The files being "specific for this device" does not rule out interaction. $\:$ (However, if the pendrive is its only means of communication then interaction would require moving the pendrive from the device to a standard computer and back to the device.) $\;\;\;\;$
May
28
answered Fast PKI for embedded device
May
28
comment Asymmetric cipher with multiple public keys
(I didn't notice that you had also answered there, and) I don't know whether a ping would work for a user who had edited the question but not done anything else on a page. $\;$
May
27
comment Operation modes of block ciphers how are used?
Do you know what $\oplus$ means? $\;$
May
27
comment Non-interactive zero-knowledge proof for discrete logarithm without random oracle
www0.cs.ucl.ac.uk/staff/J.Groth/NIZKJournal.pdf $\;$
May
27
comment Does the encryption algorithm DES perform random permutations? If so how is information not lost?
seperately $\mapsto$ separately $\:$ ? $\;\;\;\;$
May
27
revised Why is public key cryptography not widely used in governments?
inserted question mark
May
26
comment Would this be a plausible authenticated encryption scheme using nested encryption?
@Anon2000 : $\;\;\;$ Your minimal variant is close to CBC mode (you switched the order of E and xor), and subjects the block cipher to key-dependent data. $\:$ I'll be going to bed soon, so I probably won't get anything on it tonight. $\;\;\;\;\;\;\;\;$
May
26
comment Would this be a plausible authenticated encryption scheme using nested encryption?
@Anon2000 : $\;\;\;$ Actually, my original proof happened to apply to your second variant but not this page's original proposal. $\:$ I fixed it so it would apply to both of those. $\;\;\;\;\;\;\;\;$