Based on a recent Twitter conversation I had a thought about bank and credit card PIN numbers (sorry for the redundancy): are really all possible PINs issued or are some kept back because bank customers could feel uncomfortable with certain combinations of digits? And would it really matter if some of them were kept back?
It should be obvious that in case of a truly random PIN 4 identical digits are just as likely to occur as any other combination. But certain combinations just do not feel random (I don’t know how to explain it better, I’m not a psychologist).
So I’ve made a small Gedankenexperiment:
- Let’s assume that a bank issues by default a 4-digit PIN. (I know that my bank issues 4-digit PINs by default but they can be changed to any 4- to 6-digit number afterwards.)
- Customers would not accept a PIN with four identical digits (0000, 1111, …, 9999) out of fear that they might be insecure.
- An ATM allows 3 attempts to enter a PIN before locking/withholding a bank/credit card. (This limit is actually the main reason why 4-digit PINs are mostly safe, btw.)
From time to time I have (and take) the chance to dumpster dive for electronic parts. Recently, on one of these occasions, an old piece of hardware felt into my hands: a “Moser Galvanosan” galvanic stimulator.
To be honest, I’ve had no idea what it was and at first I only thought it would be a nice case for another project I was working on. After some research (out of curiosity) I thought the device is interesting enough to take some photos of its interior and write about it.
Disclaimer: I’m totally not into alternative medicine or stimulation current therapy. I’m just taking an interesting looking piece of hardware apart, that’s all!
Well, today is the first Sunday of Advent… time to play around with my cutting machine. 😉
I got inspired by a post on Hackaday.com (on Laser-cut Gift Boxes). The post presents a really nice source for DXF files for various shapes for card stock boxes. Out of curiosity I simply ‘threw’ some of their design files at my electronic cutting machine. They might save me some time (gift wrap, you know). The result is a short video of the process, nothing special:
While trying to explain the meaning of the carry digit during addition an subtraction to my oldest son, I’ve given him a nice little device to play with: the Addifix-9 number cruncher.
I’ve briefly mentioned this device before in a post. This time I’ve made a short video about the mechanical calculator in action and present more details:
In the 1950s/60s The Addifix series was sold as “Addifix-9 Taschenrechenmaschine” by the German mail-order company Neckermann. Its predecessor was the Addiator from Carl Kübler which was sold since the early 1920s [Source: sliderulemuseum.com]. The underlying mechanical principle is quite old (an documented example is the mechanical calculator by Claude Perrault from the 17th century).
The Addifix is a pocket-sized (13 x 9 cm) slide adder that can be used from both sides – one side for addition and one for subtraction. The slides (one for each digit) are handled with a metal stylus.
Had a strange effect on my Thinkpad lately – since a few days Intel AMT BIOS messages appear occasionally during boot-up:
Intel(R) Management Engine BIOS Extension v4.0.4.0007 Copyright(C) 2003-09 Intel Corporation. All Rights Reserved. Intel(R) ME Firmware version 220.127.116.114 Intel(R) AMT enabled Intel(R) AMT configuration in progress Inventory Update Field Replaceable Unit List: Intel(R) AMT Table Valid Media List: Intel(R) AMT Table Valid SMBIOS Table: Table Mismatch - Updating Intel(R) AMT [Complete] Setting New Table Fingerprint
I had Intel AMT deactivated before and I’m not using the fingerprint sensor. The AMT features seem to activate themselves occasionally in the BIOS so my best guess is that the CMOS battery is dying… Will replace it and see if the strange effect disappears.
Update: I’ve replaced the CMOS battery and so far have not experienced any AMT messages. (Well on the first boot there actually was one telling me that the SMBIOS table was rebuilt.)