SquareRootOfTwentyThree

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location Europe
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visits member for 2 years, 6 months
seen 6 hours ago

Aug
6
answered How long does it take to extract a key from a FIPS-140 Level 2 device?
Aug
6
comment How long does it take to extract a key from a FIPS-140 Level 2 device?
This question belongs to security.SE
Aug
3
revised Which of these 3 AES 128 symmetric encrypt/decrypt routines is most secure?
added 42 characters in body
Aug
3
comment Which of these 3 AES 128 symmetric encrypt/decrypt routines is most secure?
The comparison was between GCM and CTR/CBC+HMAC, not between GCM and pure CTR/CBC. In that sense, oracle attacks are defeated in all three cases, isn't it?
Aug
3
answered Which of these 3 AES 128 symmetric encrypt/decrypt routines is most secure?
Aug
2
comment Entropy of system data - use all and hash, or trim least significant bits?
Where should the randomness for deciding the length of the sampling period come from? I agree with the approach from a practical standpoint, even though I doubt it will increase the amount of actual entropy being collected (you say it will produce "more random data").
Jul
5
comment Using a derived key for CMAC
+1 and good links for KDFs. Another one is this.
Jun
30
awarded  Critic
Jun
30
comment Using bad generator in ElGamal Encryption
If the generator has not order p, you don't have Elgamal, but a variant of it I would say. Apart from that, leakage of the Jacobi symbol applies to RSA as well. Using an appropriate plaintext encoding is the correct solution in both cases.
Jun
24
answered Getting started
Jun
11
comment Hash function in PBKDF2
You got me there. I didn't know this attack happened. However, from the little I can see, the only consequence (when used for compression) is that the password space may be reduced by a couple of bits. Other constructions will be better, but I don't see it as a dramatic problem in this case.
Jun
11
answered Hash function in PBKDF2
Jun
5
awarded  Commentator
Jun
5
revised How can I protect against the failure of a block or symmetric cipher?
added 454 characters in body
Jun
5
answered How can I protect against the failure of a block or symmetric cipher?
May
30
comment are CFB and OFB really meant for streaming?
True, but then you have a non-compliant CFB implementation.
May
30
answered are CFB and OFB really meant for streaming?
May
30
comment Which MACs can be converted into a secure unkeyed hash function?
I ask the question for two reasons:i) Curiosity ii) To know the limitation of the MACs and avoid an error that quite often people tend to do. One practical reason could also be that sometime you don't have the luxury of having the whole crypto zoo available. In some constrained systems, you may only pick one or two primitives. A MAC that can be turned into a (non-standard) secure unkeyed hash is beneficial in those cases.
May
28
comment RSA/DSA: Wouldn't it make sense to sign using decoding the data hash?
In PKCS#1 (the RSA standard), the term "encoding" clearly indicates all the various steps (including padding) that turn the message into an integer suitable for the RSA algorithm. I would not say that the terminology is irrelevant, at least if we give a value to the ability to be understood by the rest of the world...
May
28
revised Which MACs can be converted into a secure unkeyed hash function?
added 2 characters in body