11,604 reputation
11049
bio website vyznev.net
location Helsinki, Finland
age
visits member for 2 years, 11 months
seen 15 hours ago

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 started programming (in AmigaBASIC) when I was 10 years old. Nowadays, I'm most comfortable using Perl, C and JavaScript. I know Java and PHP too, but I can't really say I like them. I also know some Python, but not as much as I'd like.


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.


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:


May
7
revised How do you find a cheater in Shamir Secret Sharing?
edited tags
May
7
revised Implementing secret reconstruction in Shamir's Secret Sharing
better title, copyedit, add implementation tag
May
7
comment Indistinguishability attack example
@juaninf: $m^{(0)}=m^{(1)}$ is useless, since that guarantees that nobody can distinguish the messages (since they're identical!). Now, $m^{(0)}_0=m^{(0)}_1$, on the other hand...
May
7
reviewed Approve suggested edit on Indistinguishability attack example
May
5
answered Implementing secret reconstruction in Shamir's Secret Sharing
May
4
comment Is there a secure cryptosystem that can be performed mentally?
Ps. Here's a blog post I found with more details about the current security status of RC4. And yes, RC4-52 is probably less secure, and Solitaire even less so. They may both still be adequate for manual use (where messages are likely to be few and short), though.
May
4
comment Is there a secure cryptosystem that can be performed mentally?
@SmitJohnth: If used properly (derive the message key using a secure hash, and/or discard at least the first 768 or so bytes of output, don't encrypt more than about 1GB per message key), RC4 is still considered secure, in the sense of "no known practical attacks." I still wouldn't recommend it for new designs. Hand ciphers are kind of a special case, though: on one hand, one generally doesn't expect as much security from a hand cipher as from a computerized one; on the other, it would be quite hard for anyone to generate as much encrypted material by hand as most of the known attacks need.
May
3
answered Knowing a valid salted hash for an unknown secret, is it possible to compute another valid hash?
May
3
revised Knowing a valid salted hash for an unknown secret, is it possible to compute another valid hash?
texify, paragraph formatting
May
2
awarded  Nice Answer
Apr
30
revised Adversary Two Stages
quote formatting, add ind-cpa tag; needs further copyediting, but clarification from the OP would make that easier
Apr
30
answered Adversary Two Stages
Apr
30
comment Adversary Two Stages
Could you please provide a bit more context to your question? In particular, where did you see this paragraph, and what security property is it supposed to define? I can make some guesses based on what you wrote, but it would be nice to be able to tell for sure.
Apr
30
comment Why does key generation take an input $1^k$, and how do I represent it in practice?
Related: What does the expression $1^n$ mean as a function argument?
Apr
29
comment Secure order preserving hash function
@curious: Full semantic security with OPE is impossible anyway, and, technically, being able to efficiently recover plaintexts using an encryption oracle doesn't break the alternative security definition suggested by Boldyreva et al. It still makes the system rather useless in situations where such oracle access is possible.
Apr
29
comment Secure order preserving hash function
@curious: Yes. As the paper you linked to notes at the end of section 1, order-preserving encryption is useless if the attacker has access to an encryption oracle.
Apr
29
comment Secure order preserving hash function
@curious: If I can choose a string and ask you for its hash, then the attacks still works. Even if I can only ask whether the hash of my string is less than the hash of your string, that's still enough information for this attack.
Apr
29
revised Secure order preserving hash function
edited tags
Apr
29
answered Secure order preserving hash function
Apr
29
answered what is the difference between Scrypt and PBKDF2