Henrick Hellström

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	2,646 reputation	bio	website		visits	member for	1 year, 3 months
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18h	reviewed	Approve suggested edit on srp tag wiki
18h	reviewed	Approve suggested edit on srp tag wiki excerpt
1d	awarded	Enlightened
1d	awarded	Nice Answer
2d	comment	Is Wikipedia's table about SHA-2 collisions correct? @PaŭloEbermann: I think reduced round attacks might be mentioned in this context, if the number of rounds attacks start to move up beyond some comfort limit. Otherwise mentioning them might just obscure the fact that there are logically reduced round attacks against any algorithm with multiple rounds (because after all that's why multiple rounds were made part of the design to begin with).
2d	comment	Is Wikipedia's table about SHA-2 collisions correct? @PaŭloEbermann: Nit-pick, but if reduced round attacks are relevant, if found at least one against 2 round Keccak: naya.plasencia.free.fr/Maria/papers/Keccak_differential.pdf
2d	revised	Is Wikipedia's table about SHA-2 collisions correct? Question changed
2d	answered	Is Wikipedia's table about SHA-2 collisions correct?
May 20	comment	How random are comercial TRNGS I think you are probably asking the wrong question for this forum; this is not the right place to ask for product recommendations. However, theoretical cryptography can tell how to use a not necessarily completely reliable TRNG for seeding a PRNG in such way that you at least do not make matters worse.
May 20	comment	How random are comercial TRNGS Check the documentation. How has the manufacturer ensured that the output is unbiased? By using conditioning (using what method and with which security parameters), or by tuning the hardware to ensure the raw unconditioned output does not show any statistical bias (after how many requests)?
May 19	reviewed	Approve suggested edit on One time Pad Adversary
May 19	reviewed	Reject suggested edit on What is the post-quantum cryptography alternative to Diffie-Hellman?
May 16	comment	Is this a sensible cryptographic protocol intending to reduce the impact of compromised security? Just a hint: Generally the basic idea is that you get cryptographic security by ensuring that the key never gets anywhere it might get compromised. Your protocol might give you security by obscurity at best, given your own assumptions about the threat scenario.
May 16	comment	Generate fixed length cipher text from arbitrary length plaintext Correct, the whole idea behind en.wikipedia.org/wiki/Numbers_station encryption is that the broadcast goes on forever, so that you don't get an indication when the actual traffic occurs. Obviously you are also theoretically correct about file encryption and drive encryption, but in practice there is equally obviously always a practical upper bound on how large a file might get, before you have to change medium.
May 16	revised	Generate fixed length cipher text from arbitrary length plaintext added 348 characters in body
May 16	comment	Generate fixed length cipher text from arbitrary length plaintext You hide the amount of actual plain text content. For instance, compare it to the WWII continuous broadcasts of seemingly random words. If you were listening in and didn't know which keyword to listen for, you couldn't tell when a message began or ended.
May 16	answered	Generate fixed length cipher text from arbitrary length plaintext
May 15	reviewed	Approve suggested edit on Partial collisions for md5
May 14	reviewed	Approve suggested edit on Why is H(k\|\|x) not a secure MAC construction?
May 14	comment	Why is the following RSA PRNG cryptographically secure? If you mean algorithm 5.35 in HAC, you will only output the least significant bit of each intermediary $x_i$ value.