A cute acute triangle.

Category: Interesting


Recently, on 07.07.2016, the battery tests site served its 100 000-th visitor! Huge thanks to everyone, I didn't imagine this pet project turning into something that big :)

Around the same time I uploaded the tests for 6 more battery models, as well as a second test of the Raymax AAA. The newly tested are:



In other news, this blog got a bit of a different looks (R.I.P., Verdana), as well as some rudimentary spambot protection additions :)

Posted in category Interesting -- clock 8 Jul 2016, 17:21, 2 comments


Battery tests update (2)

I'm with a broken wrist this month and I took upon the opportunity to clear off the backlog I had accumulated for the battery tests website, a total of 29 models, mostly rechargeables:






Thanks to all the great people, who turned them in for testing!




Posted in category Interesting -- clock 16 May 2015, 00:15, 0 comments


Battery tests update

I haven't updated the battery tests page for a while, but the project is not dead at all. I've been busy with other things (which I will announce here eventually), but the test database has been slowly accumulating new entries, which await to be published, so I have 1½ year backlog to push :)

There are several new things,

- A Facebook page;
- 9 new NiMH AA batteries are tested, see the changelog;
- Date of tests is now noted in the "detailed page" for each battery.

Posted in category Interesting -- clock 30 Sep 2014, 18:07, 0 comments


Battery Review

Here's how you waste the energy equivalent of a hand grenade¹ in the name of science:


As I promised almost an year ago: I wanted to do a comprehensive test of the non-rechargeable batteries sold in Bulgaria. What's the capacity of each brand, as well as the performance/price ratios.

I expanded the test several times (as it turns out, it is important to test the cheap brands), and it currently includes 29 AA battery models, 18 AAAs, 14 nine-volts, as well as 26 rechargeables. More tests are to come :) Some of the models I tested were donated by the kind people from the HardwareBG forums, so I want to thank them here, for making this review more complete.

The website of the review is:

Share and enjoy - this review needs to reach as much people as possible.

¹ In case you're curious: a hand grenade has about 400-600 kJ. The energy of the discharged batteries so far exceeds 1000 kJ...

Posted in category Interesting -- clock 22 Mar 2013, 11:14, 0 comments



Last week I got some coursework to do, for "Basics of CAD systems" in the Uni. Well, I was kinda bored, so I had it "lets just EXPLODE and make it way above the requirements". Just for the heck of it.
The result turned out quite satisfactory, really. You can check it out here: FooCAD (Windows build).
(don't forget to try out the crossbar, hey!)

Besides that I got into my next PIC project. I had an amazing shopping experience when the order list to Farnell was like more than one A4 page :)
No fancy mechanics this time. In compensation, the electronics department would get more attention now. In my current view, ALL the 20 pins of the PIC would be used. I have that feeling it would get a big hairy mess in the end.
To keep the suspense, no more spoilers for you :D

Posted in category Interesting -- clock 12 Feb 2011, 21:10, 0 comments


Bug in WinRAR password input, or...?

Two or three weeks ago I stumbled upon a strange (yet rare) bug in WinRAR's password handling implementation. I abused WinRAR by giving it a password in cyrillic letters (the bug doesn't appear if you use the usual ASCII 7-bit set). The whole experience boils down to the old saying: "Just because a program is written by a patriotic russian guy doesn't mean it is unicode-safe" :)

So, let me get slightly into the details... did you know, that you could use non-ASCII characters for archive passwords in WinRAR? Well, I didn't know either, and so I went to find out. This was along the polishing touches on my RAR password cracker (which I recently sped up by 10-20%, etc.). I started with WinRAR and created a test archive, using the word «България» as the password. WinRAR happily accepted the password and created the archive. On decryption, it also happily accepted the same password (and rejected some random other one). The console-mode utility for win32 also seemed to work under cmd.exe window.

Step 2: I transferred my test RAR to the Linux box, where this time it didn't decrypt (it said my password is wrong). That was strange — initially I thought that the `unrar' utility author had made some implementation mistake in the unicode string handling. However, after a bit of debugging, it turned out that this was not the issue, as my Fedora 11 terminal was passing the utf-8 string correctly and all the underlying machinery worked flawlessly. Actually, the console `unrar' utility seemed to perform the right job! So, after a bit tinkering with the Win CLI again, I noticed, that whenever I typed some cyrillic characters in the terminal, question marks appeared instead. So, in cmd.exe, "България" would equal "????????". When testing the latter "password" (the eight question marks), the archive decrypted successfully.

The cause of this strange behaviour turned out to be hidden in Control Panel->Regional and Language Options->"Language for Non-unicode programs". When I set it to "Bulgarian", both programs (WinRAR and the CLI `rar') behaved correctly, with "България" being no more equal to "????????".

So you may have probably guessed what the bug is? Well, consider the case with a clueless dude, sitting in front of a all-default-setup Windows computer (where the aforementioned Windows setting is not "Bulgarian"). So, the dude creates an archive, and puts up the hyper-strong password "ХакерЩрасе". But in reality, the password he actually sets for the archive turns out to be the trivially-breakable "??????????"!

Ironically, it is evident from the unrar utility's source code, that the author (who is russian btw) has tried hard to support non-ASCII characters... but his program turns out not to be unicode-safe anyway.
The bogus interpretation of cyrillic symbols as question marks hints us to a subtler problem with WinRAR's security: the password input dialog should detect such "patently weak" passwords and (at least) warn the user, so he or she can consider using a stronger password. This way, hidden implementation problems like the one I mentioned will be detected as a simple side-effect.

Posted in category Interesting -- clock 22 Apr 2010, 03:02, 0 comments

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