13,720 reputation
11458
bio website vyznev.net
location Helsinki, Finland
age
visits member for 3 years, 7 months
seen Mar 24 at 1:45

I'm not really a cryptographer, I just play one on the Internet. ;-)

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.


Dec
2
reviewed Approve Why use two affine transformations in Multivariate Cryptography?
Dec
2
reviewed Close Why is appending the key to a mesage and then hashing that insecure if the hash isn't weakly collision resistant?
Dec
2
answered Splitting a password for dual roles
Dec
2
reviewed Leave Open Splitting a password for dual roles
Dec
2
revised Splitting a password for dual roles
copyedit
Dec
2
reviewed Leave Open Who uses the RSA BSAFE library?
Dec
2
reviewed Close becoming a cryptographer after math studies
Dec
2
reviewed Close Hash function with values in a multiplicative group of prime order
Dec
2
reviewed Close How does identification currently work with the German identity card?
Nov
30
comment Is it theoretically possible to construct a string that contain its own hash value?
@Alex: With respect to what parameter? With respect to the hash output length $k$, it's clearly in NP($k$), assuming that computing the hash of a given string is in P($k$). By the argument given above, if the hash is secure in the sense described, finding such a string cannot be in P($k$). (Yes, the existence of secure hash functions implies that P ≠ NP.) With respect to the input string length, finding such a string (if there is one to be found) takes on average a constant number of hash evaluations, and is thus in ZPP.
Nov
30
reviewed Approve cmac tag wiki excerpt
Nov
30
reviewed Approve cmac tag wiki
Nov
28
comment Can homomorphic encryption filter?
However, using methods similar to those in your answer, it would be possible to query e.g. for "the first 50 students with scores higher than 90%" (with null values returned if there weren't that many matching records).
Nov
28
revised Can the XOR of two non-collision-resistant hashes be collision resistant?
added 778 characters in body
Nov
28
revised Can the XOR of two non-collision-resistant hashes be collision resistant?
copyedit
Nov
28
answered Can the XOR of two non-collision-resistant hashes be collision resistant?
Nov
28
revised How can I construct a distinguisher given an inverter?
edited tags
Nov
28
reviewed Reject
Nov
28
reviewed Approve md2 tag wiki
Nov
28
reviewed Approve