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Jun
1
comment Shamir secret sharing with field 2^8
You're missing that you can also try to guess the secret. $\:$ What is k? $\;\;\;\;$
Jun
1
comment Why not put MAC in fixed position and cover padding for MAC-then-encrypt?
It seems to pretty clearly be m0 || m1 || m2 || padding || MAC of m0+m1+m2+padding, $\hspace{.17 in}$ where padding is chosen to make the length of that concatenation an integer multiple of the block size. $\hspace{.1 in}$
May
31
comment Why using AES in ECB (Electronic Code Book) mode a bad idea?
On the other hand, that makes your post's title completely different from your post's body. $\;$
May
30
comment Is this adaptation of one-time-pad still secure?
Yes, they can determine $\:$ next_x xor next_y $\:$. $\;\;\;\;$
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 $\;$