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2h
comment Large file validation on an embedded system through hash and encryption
It would probably be better to sign "the MD5 hash with a private key and return" a signed "hash to the embedded system", rather than trying to use encryption for that purpose. $\;$
7h
comment Secure way to derive separate encryption and MAC keys from a single master key?
@owlstead : $\;\;\;\;$ "for less structured" $\: \mapsto \:$ "for more structured" $\;\;$ ? $\;\;\;\;\;\;\;\;\;$
1d
comment Operation which needs much computing power to be created, but just a little to be solved?
The "just a little to be solved" part is easy: declare that 0 is always a solution. $\;$
1d
comment Operation which needs much computing power to be created, but just a little to be solved?
@StephenTouset : $\:$ How? $\;\;\;\;$
1d
comment How to compute 3P from elliptic curve where P is (28, 8)
... for what EC group? $\;$
1d
comment Format Preserving Encryption for 32 or 64 bit plaintext values
I would recommend using HMAC, since it is presumably a secure PRF. $\:$ I have no idea what the impact on performance would be. $\;\;\;\;$
Oct
20
comment Can we run a probabilistic function on ciphertext with Functional Encryption (or Attribute Based Encryption)?
@TravisMayberry : $\:$ That depends on what the PRF takes as input. $\;\;\;\;$
Oct
20
comment Can we run a probabilistic function on ciphertext with Functional Encryption (or Attribute Based Encryption)?
@JianLiu : $\;\;\;$ If $sk_f$ can be quantum, then it might be possible "to prevent Bob from providing the same randomness to $\hspace{.04 in}f$" every time. $\:$ There are non-deterministic PRNGs, but that would just move the problem to preventing "Bob from providing the same" entropy to the PRNG every time. $\:$ Do invoker-randomizable PRFs count as "non-deterministic"? $\;\;\;\;\;\;\;$
Oct
19
comment Can we run a probabilistic function on ciphertext with Functional Encryption (or Attribute Based Encryption)?
You could instead "contain within $f$ a" PRF, so that Bob can only provide "the same randomness to $f$" on each call with the same input.
Oct
17
comment Existential Unforgeability of signature scheme against Adaptive Chosen Message Attack
No; I'm just making sure you're aware that EUF-CMA is not the strongest notion. $\;$
Oct
17
comment Existential Unforgeability of signature scheme against Adaptive Chosen Message Attack
(Also: Have you seen "the concept of" Strong "Unforgeability of signature" schemes "against Adaptive Chosen Message Attack"?) $\;$
Oct
17
comment Existential Unforgeability of signature scheme against Adaptive Chosen Message Attack
csee.wvu.edu/~xinl/library/papers/comp/goldwasser1988.pdf $\;$
Oct
16
comment Cryptography system that limits the length of the encypted message
That only affects how easy/hard it will be to do format-preserving encryption $\hspace{1.74 in}$ on the space of 160-character strings. $\;$
Oct
16
comment Cryptography system that limits the length of the encypted message
Does the list of allowed characters have an even number of elements? $\;$
Oct
15
comment Encrypted read-only message queue
You should not be encrypting "with the private key". $\:$ See this question and this answer. $\;\;\;\;$
Oct
15
comment Is there any existing cipher capable of scaling from a 1 bit key up to a one-time-pad?
Three other regions along that continuum are honey encryption, entropically-secure encryption, and encryption that remains information-theoretically secure against key-dependent messages.
Oct
10
comment How does MD5 process text which is shorter than 512 bits
en.wikipedia.org/wiki/MD5#Algorithm $\;$
Oct
8
comment How do I generate a number for a lottery and later proves its existence
@tylo : $\:$ I mean a collision with short inputs. $\;\;\;\;$
Oct
7
comment How do I generate a number for a lottery and later proves its existence
@tylo : $\:$ One uses a short collision in the actual hash function. $\;\;\;\;$
Oct
6
comment How do I generate a number for a lottery and later proves its existence
The drawback "of doing this over" a perfectly binding scheme is that, for each hash function, there exists a fast way to break the binding property.