12,328 reputation
11352
bio website vyznev.net
location Helsinki, Finland
age
visits member for 3 years, 3 months
seen Nov 20 at 10:54

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:


Oct
16
comment How does one use AES block cipher modes of operation?
You could start reading the input a bit earlier, at the 250th cycle (or even earlier, but that wouldn't help with throughput). That way, when the encryption was finished on the 266th cycle, you'd already have the next input block buffered and ready for encryption. Of course, that would require an input buffer separate from the AES encryption registers.
Oct
14
comment Encoding numbers that can be decoded mentally?
Or, even better, just make a simple database of the objects and their prices, with a unique (possibly random) ID for each object, and tag the objects with those IDs. Assuming you don't have billions of items, you phone should be able to store the database just fine. As a bonus, you can have the phone display the name (or a description) of the item, so you can tell if the customer has switched the tags.
Oct
12
comment How does one use AES block cipher modes of operation?
Yes, you need to send the IV / nonce to the recipient. The usual way is to just prepend it to the ciphertext. Also, yes, the CTR, ECB and OCB modes are easy to parallelize. AE modes using CTR as a component (EAX, GCM, SIV, etc.) can do the CTR mode en/decryption in parallel, but the authentication is typically less parallelizable. CBC and CFB mode encryption is inherently serial, but decryption can be parallelized. OFB mode is inherently serial in both directions, although it's possible to precalculate the keystream.
Oct
9
reviewed Approve suggested edit on tweakable-cipher tag wiki
Oct
9
reviewed Approve suggested edit on tweakable-cipher tag wiki excerpt
Oct
8
comment How does redundancy in a file effects performance and security of encryption?
Exactly.​​​​​​​
Oct
8
comment how much trust can we place in protocol verifiers?
Related, possibly duplicate: Is there an automated security protocol verification tool?
Oct
8
comment Definition of cryptographic advantage vs. probability of success
Why do you think you can't divide an advantage by 2? If I can guess $b$ with probability 0.50002, and you can guess it with probability 0.50001, then your advantage is $\frac12$ of mine.
Oct
8
comment Encryption algorithms and the “One-Time pad”
Possible duplicate of Why not the one-time pad with pseudo-number generator (or maybe What is the difference between a stream cipher and a one-time-pad?).
Oct
8
answered How does redundancy in a file effects performance and security of encryption?
Oct
8
comment How does one use AES block cipher modes of operation?
BTW, I think you're probably confused on a fairly fundamental level about how block ciphers work. I'd suggest reading the Wikipedia articles on block ciphers and block cipher modes of operation before even looking at my answer below.
Oct
8
answered How does one use AES block cipher modes of operation?
Oct
8
reviewed Approve suggested edit on fortuna tag wiki excerpt
Oct
8
reviewed Approve suggested edit on fortuna tag wiki
Oct
7
answered Making counter (CTR) mode robust against application state loss
Oct
2
comment Shamir's Secret Share Over the Reals
Sort of. If we have some bounds for $S$ (say, we know that $a\le S\le b$ for some $a,b\in\mathbb R$), then in principle we can, say, let $r$ be normally distributed with standard deviation $\sigma$ much greater than $b-a$, in which case any effect of $S$ on $y_1$ will mostly be buried in the noise. (Of course, then we still have the problem that we cannot really store a random real number picked from a continuous distribution in a finite amount of memory, so we'll have to settle for some discrete approximation, which introduces new leaks.)
Oct
2
awarded  Nice Answer
Oct
1
answered Shamir's Secret Share Over the Reals
Sep
30
answered Are NIST's changes to Keccak/SHA-3 problematic?
Sep
28
revised Why does Shamir's Secret Sharing Scheme need a finite field?
rewrite for better focus