Category Archives: Personal

Texas Executed Offenders’ Last Words

An artist friend of mine gave me this idea, so here is the list of the most used words of those executed in Texas, from their last statement:

word       frequency
     you   4.670330
     and   3.945360
     the   3.670635
     for   2.701465
    love   2.419109 **
    that   2.190171
     all   2.113858
    have   1.663614
    this   1.297314
   thank   1.030220 **
    know   1.014957
  family   0.969170 **
    your   0.908120
     not   0.839438
    will   0.808913
     god   0.801282 **
    want   0.801282
   would   0.778388
    with   0.755495
     i'm   0.755495
   sorry   0.747863 **
    like   0.740232
     say   0.679182
     but   0.641026
    life   0.595238 **
    what   0.579976
   there   0.549451
   ya'll   0.534188
    hope   0.488400 **
    them   0.488400


On Testing and Security Engineering

I have been working in a large organization for quite a while now where I have seen a lot of testing going on. As an information security engineer, I naturally aligned more with testing and indeed, information security assurance does align well with testing: It’s done on a continuous basis, its results usually mean work for developers, operations people, system architects, etc. and not caring about it is equivalent to accepting unknown risks. Since I have been working in an environment where testing was paramount, I have been digging more and more into the testing literature.

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CryptoMiniSat: 8000 commits later

The GitHub repository for CryptoMiniSat just hit 8000 commits. To celebrate this rather weird and crazy fact, let me put together a bit of a history.

The Beginnings

CryptoMiniSat began as a way of trying to prove that a probabilistic cryptographic scheme was not possible to break using SAT solvers. This was the year 2009, and I was working in Grenoble at INRIA. It was a fun time and I was working really hard to prove what I wanted to prove, to the point that I created a probabilistic SAT solver where one could add probability weights to clauses. The propagations and conflict engine would only work if the conflict or propagation was supported by multiple clauses. Thus began a long range of my unpublished work in SAT. This SAT solver, curiously, still works and solves problems quite well. It’s a lot of fun, actually — just add some random clause into the database that bans the only correct solution and the solver will find the correct solution. A bit of a hackery, but hey, it works. Also, it’s so much faster than doing that solving with the “right” systems, it’s not even worth comparing.
Continue reading CryptoMiniSat: 8000 commits later

My Dell Vostro 3560 review

In this post I would like to share with you a personal review of my new business line laptop from Dell, the Vostro 3560. It’s a 15.6″ laptop that has Full HD screen using TN display technology, a 750GB HDD spinning at 7500rpm, 6GB of DDR3 RAM clocked at 1600MHz, with the highest possible Core i7 processor available for this machine, the i7-3612QM, that goes to 3.1GHz with all cores still active.

Overview of the laptop

The good

First, let me talk about what I found to be great about this laptop. The display is great: it’s sharp, the colors are good and it’s bright enough even in strong sunlight — though admittedly here in Berlin there is not much of that.

The keyboard is also magnificent. It’s one of the best keyboards I have ever used, even though I am very particular about my peripherals, especially keyboards and mice. I used to own business Thinkpads and this is the first keyboard that I have found to be as good as or maybe even better than a Thinkpad keyboard.

The system is built sturdily, and the materials used don’t feel cheap in your hands. Though the system isn’t light, it feels easy to hold due to its rigidity and smooth (but not slippery) surfaces.

Finally, the system contains extras that are only mentioned in the service manual. For example, there is an mSATA socket inside the laptop, meaning you can plug a 256GB mSATA SSD into the system in a couple of minutes for a reasonable price (around 200EUR), significantly speeding things up.

The mediocre

The CPU is a trade-off. It’s not the i7-3610QM which would go up to 3.3GHz with all cores still active. The reason for this is interestingly not price: the two CPUs cost the same from intel — the reason is heat removal. The CPU installed only generates 35W of heat while the other generates 45W. Essentially, Dell didn’t work hard enough on the cooling system and the result is that a better CPU cannot be installed. Unfortunately, Dell is not the only one that couldn’t install the 3610QM, other manufacturers such as Sony with the Vaio S series had the same issue. Naturally, Apple with the new MacBook Pro lineup didn’t mess this up.

The included charger is rather bulky. Interestingly, there is a slimmer charger available, for a mere 114 EUR — the one included costs 50EUR on the same Dell webpage. I find this to be rather disappointing.

Bulky charger included
Slim charger, available at 114EUR

The wireless card inside the system doesn’t support 5GHz WiFi. This sounds minor, until you go to a conference or a public place with a WiFi where everyone seems to be able to connect, except you. 2.4GHz WiFi uses a band that is substantially more noisy and since routers on that band cover more area, if many people are in the same place, connection can be very spotty. In comparison, my IBM X61t, released in 2007 (!) had 5GHz WiFi, so it’s hardly new technology. In fact, for about 30EUR you can change your WiFi card inside the case for one that supports Bluetooth+802.11abgn, i.e. all that is inside plus 5GHz WiFi. I still cannot understand why a computer that costs 900+ EUR would cheap out on such a component — especially since Dell can get bulk discount, so the upgrade for them would be around 10 EUR at most.

The system comes with a DVD writer included, but I don’t have any use for that. Who uses DVDs nowadays? If I want to watch a movie, I use Blu-Ray — after all, the display is Full HD! Having a Blu-Ray option would have been easy for the manufacturer, as the DVD player included is a standard one, so it can be easily swapped to an internal notebook Blu-Ray reader. Such readers cost around 60EUR at any online retailer. In fact, a Blu-Ray internal writer would cost no more than 80EUR. Dell missed out on this completely, for no good reason. Yes, it’s for business, but even business people need to back up their HDD and a DVD writer with a capacity of 4GB won’t be of any help.

The bad

Build quality is terrible. This is very surprising at this price range and in this category (i.e. business). First off, the screen’s backplate fits so badly to the front that there are holes larger than 2mm on the right side, and almost none on the left:

Left side of panel
Right side of panel

The same, though less accentuated, is true for the palmrest. You can clearly see that the plastic fits differently on the two sides, and in fact fits unevenly on both:

Left side of front
Right side of bottom


Similarly, the bottom sticker of the laptop with the most important piece of information, the Service Tag, is of such a low quality that after only 2 months of use the numbers got completely erased, and only the barcode (blacked out for privacy) remains readable:

My Service Tag — other than the barcode (blacked out) it’s unreadable

Finally, Linux support is terrible. I wanted to get reimbursed for the Windows 7 licence, but they refused it, which I think is clearly illegal, but of course I don’t have months to waste and money to burn to get some 50-100 EUR back. In the same spirit, there is no proper support for controlling the fan under Linux, as the highest level of the fan cannot be attained with the linux driver, and there is no proper palm detection support for the touchpad. The AMD Linux driver available at the time of purchase crashed X11 at startup, but the new one (fglrx 8.980) is flawless, and I have to commend AMD the on that.


The Vostro 3560 is a nice piece of machine but it’s not quite business quality and its makers prefer not to hear the word Linux uttered. However, if you are ready to shell out some money on a Blu-Ray drive, don’t intend to use Linux and are content with mediocre build quality with holes between elements the size an edge of a penny, the Vostro 3560 is a good choice. Otherwise, maybe hold out for a better offer.


Q-DIMM, an “innovation” by ASUS

Lately, I have been having boot problems with my computer: the system would sometimes fail to boot, and at other times, it displayed the wrong memory readings. I was puzzled, so I took a look. I have six memory DIMMs installed in an ASUS motherboard. Memory modules are usually retained in their slots using two latches:

The point of these latches is to keep the memory modules in place when the computer is moved around. They thus serve the same purpose as the screws for PCIe slots or the mounting holes for the CPU coolers. My motherboard, however, is made by ASUS, and it has a “feature” called Q-DIMM, which is supposed to ease the installation of memory modules when the system has the video card already installed. This “feature” is rather simple: the latch on the right is completely missing:

Unsurprisingly, over time, some of my memory modules simply came out from their slots, making the system completely unstable. And I am far from being the only one who has had this problem.

Most probably the person who came up with this “feature” wasn’t an engineer, but a PR person. It is however rather sad that a technological company such as ASUS should make technical decisions based on PR. By the above logic, I wonder why they didn’t remove both latches. And while they were at it, get rid of all those pesky screw holes for the PCIe slots, and the mounting holes for the CPU cooler, too — things would be much easier to install!

Seriously, though, this is just unbelievable. Fun part is, ASUS sells this “feature” as an innovation that is available only to their high-end (and more expensive) motherboards. I don’t know whether to laugh or cry that you have to spend less to get a more robust, stable system.