• Things usually are simpler than they look. For example the TCP congestion control algorithm. Still, they can be very powerful (this is similar with DES for example – which I’ve had to reimplement for “educational purposes”, and found that, at the core, it was surprisingly simple).

• It is very interesting to “peek behind the curtains”. Reading about the TCP congestion control made me better understand the “TCP DoS vulnerabilities” talk from 25C3. You can look at the presentation online. It is the case IMHO that during 2009 someone will release a “library” to perform these types of DoS attacks and it will get incorporated in every *bot out there, making it the “SYN flood” of 2009 (what do you know? a free 2009 prediction ;-)).

PS. As this blog post points out you can get the CC logos in vector format from the CC Logo Download page (there are little links under each image with different fileformats). OpenOffice 3.0 still can’t import SVG. WTF? Luckily I had Inkscape installed and exported it as a high-resolution PNG.

A little background for those foreign guests who are still reading: in Romania the masses started using debit cards fairly recently (around 2 years) when the banks started offering packages which made cheaper for the employers to offer pay this way (as opposed to withdrawing large sums on payday and giving it to people in cash which was the traditional method). There is no almost zero credit card usage though. The number stores which accept credit cards is also low (or very low, depending o the region of the country) and the processing takes a long time (I’m talking about minutes, but even 2-3 minutes are longer than it would take to pay cash).

Given this background it is fairly obvious that most of the people are not used to their cards. Usually their first action is to withdraw the full amount from an ATM (this is one of the reasons credit cards failed – because many people wrongfully assumed that the credit limit was the total amount in their accounts and got a very unpleasant surprise the next month). This situation is made even worse by the fact that those almighty engineers who designed the program for the ATMs never ever tested it on an average human being. Here are some flaws I personally identified (and I’m sure there are many more which an experienced user interface designer could spot):

• Use of convoluted language – this is the biggest flaw. I really don’t understand why they couldn’t use simple terms taken from every day life like cash and instead they used some words which look like they were taken out of economics books. Not that I have something against economic sciences, but I’ve seen many people who simply don’t understand the wording of the messages
• Use of error messages which don’t describe the cause – for example when the machine says: I can only give you X amount of money, it fails to mention that this is because it has only small bills and only a given number of bills fit through the space where it supposed to eject it
• Not highlighting the error messages – people are so used to not understanding the messages that they don’t even read many of them. Better wording with some visual cue to highlight error messages would probably help.
• Presenting irrelevant options – I don’t know if there is truly a technical reason behind this (it may well be), but some ATMs display options for my card which are clearly not valid and surely they confuse people even more (given the fact that they are not written in an everyday accessible language – see point 1)