Older blog entries for ajk (starting at number 30)

Ok, it's been an extremely busy week. I've even had to cut down on sleep in order to stay well prepared in the intensive course I'm giving at the Summer Secondary School here at university.

The course subject matter is functional and logic programming. I've got 30 supervised hours total for it and twenty high-school students. I've decided to go on about it from an unusual angle: I deliver 16 hours of theory about logic and functions, emphasis on programming but methodology certainly mathematical. That is, I teach them (informal) formal logic and (a hacked version of) lambda calculus. Six hours are used to check homework on the theory and six hours total on a computer putting the theory into practice. With careful (he says!) design of the lambda calculus notation, and with a heavy flavoring of it towards Haskell (including a Hindley-Milner style type system, but no type classes as of yet), the theory of functions turns into practice in Hugs quite easily. They seemed to digest even recursion quite easily today.

I am pleased.

And I need rest. Desperately.


rconover, I've actually sat in a room where it's hotter than 100 degrees Celsius. Several times. Am not dead yet. And it's a fun experience, as long as you don't spend too much time there.

Things I hate: ANSI C. Why is it that even Europeans must grovel on the feet of an American standardization organization? We have an international organization, ISO, you know. And ISO C (1990) is for all practical purposes equivalent to ANSI C (1989).

Thinks I like: ISO standard date format. Now is 2000-07-30T19:15Z. You all got that?

Continued preparing for the course. Did very little else.

A lot has happened since the last diary entry:

  • The programming course I was assisting teacher on has finished.
  • I've been employed as a research assistant by the Department of Mathematical Information Technology, in the Jyväskylä Hyperstructure Group led by Tuomas Lukka. I'm supposed to work on GZigZag, the Writer's Text Editor (as a GZigZag applitude) and PolyGlot (a modular parser framework), although mostly it's been about the first.
  • I'll be teaching a 30-hour course on 2000-08-01/10 about functional and logic programming for upper secondary school students as part of the Summer Secondardy School here at Jyväskylä. I'm preparing frantically.
So I've been busy. Deal with it.

Released catdvi 0.10, which includes a manpage thanks to Björn Brill.

What have I been doing the last several weeks, hiding behind an ignored journal? Mostly studying and teaching; they have taken most of my time. And I've been reading... It has not been a fertile ground for any hacking activities. Let's hope it'll change for the better.

I discovered the GPF and Waiting for Bob comic strips. And I purchased both User Friendly books. I have little difficulty to identify with UF's AJ (who - interestingly - shares a nickname with me) and GPF's Nick. Unfortunately they both have an advantage over me: they do not weigh as much :-(

Got a visit from an angry amanuensis (is that the correct English term?) that we should leave the office we had been given ASAP (it was on loan from another department, and they needed the room for a foreign visitor). With some interdepartmentary diplomacy I was able to get us a new office, which is bigger and spacier than the previous one and is directly attached to the computer lab where we teach. I think it went quite well in the final analysis. The problem is, our new office space was reserved by a professor who has not used it in the last year, and we were given that space without asking the professor. Oh well, we need that office only for a month or so anyway. And I got my own work computer, on which I immediately installed Debian potato (as of first test cycle). The install system has really improved.

No time to code today, I am sorry to report. But yesterday I finally settled on two random number sources for Winters: /dev/random for the top-security stuff (keys etc) and a /dev/random-seeded MD5-based PRNG for the workhorse random numbers. And it works too, although I may have to rewrite the MD5 implementation (stolen from dpkg) for increased portability.

struct block decrypt(void * sc, struct block const bl)
        struct block rv = { 0, NULL };
        return rv;

That's what caused the zero-size decryption result. I feel so damn dumb now.

Wrote some more of Winters networking code. For some strange reason the receiver decryption result for the packets have size zero. I need to investigate that.

My copy of Schneier came on Tuesday, have been reading it enthusiastically.

I am offering some Debian packages for adoption by registered Debian developers or sponsored prospective developers.

Today started both summer courses: the programming course (where I work as a teaching assistant) and the topology course (where i sit and study). The next one and half months is going to be busy time for me.

Made an offline copy of the potato i386 archive for my father, and installed a basic potato system for him. This took all my free time today, so I did not have any time to code or spec.

I've been specing and implementing Winters network protocol. It's going slowly. I managed to write my own Blowfish implementation which seems to be correct (passes a simple encryption/decryption test where I know the correct ciphertext). I noted, however, that the online description of Blowfish is ambiguous in many occasions, most notably it omits information on endianness issues on many occasions. Apparently my guess "big-endian über alles" was correct. My Blowfish implementation is not one of the fastest, but it is the only one that I know that does not require separate source configuration (either manually or with Autoconf) and is written in C.

Did you know that GCC means "Graphic Character Combination"? I didn't, until I ran across the ECMA-48 standard.

I should've known. I presented the session management part of the Winters protocol to a security newsgroup. It was pretty much shot down. They even asked why I was designing my own protocol instead of using SSL or SSH or some other well-established protocol. The answer is that they don't take advantage of one unique aspect of the application I'm designing the protocol for: all legitimate sessions are necessarily derived from a root session. My protocol thus can do without all long-term keys, symmetric or asymmetric. Oh well, back to the drawing board (and I'm getting a copy of Schneier).

I decided to rebuild my home system, which naturally runs Debian, from scratch to do away with all its cruft. Of course I forgot that I need the drivers diskette even in the NFS install, and of course I noticed that after wiping out my previous install. I had no access to the network anymore. I had several past versions of Debian on CD's but alas, my CD drive is broken. I even had some old boot disks for Debian 1.3, Debian 0.93r6, and Slackware 3.0. Unfortunately, none of them would build my system into a shape where it could reach out to the net to grab the stuff I needed. Ended up calling a nearby friend and using his machine for creating that much needed drivers diskette.

Today my network connection suddenly dropped. Turned out my network card was loose and had disconnected.

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