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bio website vyznev.net
location Helsinki, Finland
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visits member for 3 years, 5 months
seen Jan 21 at 12:14

I'm a PhD student in biomathematics, working on stochastic individual-based models of evolution in spatially structured populations. My other interests include cryptography, programming games and puzzles, photography and graphic design.


I'm the main author and maintainer of the Stack Overflow Unofficial Patch (SOUP), a user script for browsers with GreaseMonkey-compatible user script support (Firefox, Chrome, Opera, possibly Safari) that fixes or works around a number of outstanding issues with the Stack Exchange user interface.

I tend to answer a lot more questions than I ask. Some answers I'm rather proud of:

CC-Zero Please consider any (original) code I post to Stack Overflow and other Stack Exchange sites to be released under CC-Zero unless stated otherwise. You may do whatever you want with it and don't have to credit me in any way, although of course that would be nice.


Nov
6
answered Security proofs for CBC mode
Nov
6
awarded  Popular Question
Nov
5
wiki created commutative-encryption description
Nov
5
wiki created commutative-encryption excerpt
Nov
5
revised Transparent cipher
edited tags
Nov
5
revised Software implementation of a commutative cipher?
edited tags
Nov
5
revised Are there any secure commutative ciphers?
edited tags
Nov
5
revised Can we decrypt in this order when the message is encrypted twice?
edited tags
Nov
5
reviewed Reject
Nov
5
reviewed Reject
Nov
1
comment If I have the unencrypted text and the encrypted text, can I calculate the key?
Related / near duplicates: crypto.stackexchange.com/questions/2949/… crypto.stackexchange.com/questions/3952/… crypto.stackexchange.com/questions/3832/… (and these are just the ones I've answered myself; I'm sure there are more)
Oct
28
comment Why are the initial states of hashes functions (like SHA-1) often non-zero?
@user8911: Typically, the kinds of things you may want to avoid are e.g. having the IV be equivalent to itself rotated by some number of bits, or perhaps reversed and/or inverted, or otherwise having some simple bit pattern that might make an attacker's work easier. A random IV is very unlikely to have such a pattern, but may raise suspicions if you can't explain why it was chosen; hence "nothing up my sleeve" numbers, which are supposed to be free of such patterns while still not having enough degrees of freedom to hide a back door.
Oct
27
comment Are there attacks that break collision resistance but not preimage resistance?
OK, great! I've remade the edits.
Oct
27
revised Are there attacks that break collision resistance but not preimage resistance?
rolled back to a previous revision
Oct
27
comment How can I prove/disprove that a construction yields a secure PRG?
Is the input space of your PRG really $\{0,1\}^*$? If so, what's the distribution of the inputs? (It can't be uniform, since there is no uniform distribution over $\{0,1\}^*$.)
Oct
27
revised What's the difference between the long term key and the session keys?
deleted 2 characters in body; edited tags; edited title
Oct
27
comment Are there attacks that break collision resistance but not preimage resistance?
I tried to copyedit your question, but I realized that I wasn't really sure whether you were asking for attacks that break preimage resistance but not collision resistance, or the other way around. Could you please clarify that?
Oct
27
revised Are there attacks that break collision resistance but not preimage resistance?
rolled back to a previous revision
Oct
27
revised Are there attacks that break collision resistance but not preimage resistance?
added 384 characters in body
Oct
25
comment Can you help me understand how RC4-52 is done using pen-and-paper?
Somewhat related: crypto.stackexchange.com/questions/844/…