IoT Temperature and Humidity Sensor
This is a walkthrough for setting up a NodeMCU with a Si7021 temperature and humidity sensor as an IOT device.
It will collect sensor information, and continuosly report them to Grafana and MQTT.
Read more ...Advent Of Code Day 1
Advent of Code has started again - here is a PHP solution to Day 1 - including two code-golfed variants :)
Read more ...Git commit signing
I’ve been trying to set up git commit signing, and was treated with the following error:
error: gpg failed to sign the data
fatal: failed to write commit object
Optimizing Alexa lambda functions
A basic NodeJS Alexa fact skill based on the fact template builds to a 4.5 MB deployment package (and that is with best zip compression). This is way too much for code which does just spit out a random string.
Read more ...automated gitolite backups
Since I run a gitolite server for my private projects, I needed a way to regularly backup these repositories. The following script is run via crontab as the gitolite user, and creates bundled versions of all hosted repositories. Those are then pushed via SMB to a network attached storage.
Read more ...Alexa Developer T-Shirts
So I got one of those T-Shirts Amazon offered for Alexa Skill developers in Germany. Quite cool design, and those binary numbers on the front apparently were supposed to mean something. Actually supposed is the key word here, as it seems someone over at Amazon did produce a typo ;-)
Read more ...Shiny new domain
Got myself a shiny new hipster domain. Took the chance to move hosting to AWS, and ditch wordpress in favor of a static generated site by Hugo.
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512-Byte Clock
So I coded a tiny little 512-byte program fitting into a bootsector, which displays a big clock.
I even managed to squeeze switchable fore- and background colors and a key to toggle 12 vs 24 hour display in there. Now the sector is filled up to the limits, only 1 byte left. That’s 509 Bytes of Code & Data for a functioning clock program + 2 Bytes for the bootsector marker.
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Breaking QuickStego
Target: QuickCrypto’s QuickStego Version 1.2.0.1
QuickStego is a tool that can hide unencrypted text data in BMP image files.
The first look with PEiD reveals a Visual Basic executable, the crypto analyzer tells us something about CRC32. This may be used as some kind of verification of the data.
Trying the program on some small Bitmap files shows an unchanged file size, but many changed image data bytes, even for a message as short as one char (I used ‚A‘ for the test). The text is thus hidden directly in the pixel data, presumably by LSB method, with some overhead for management.
Read more ...Reading SDRAM configuration data with the Bus Pirate
SDRAM DIMMs have a standardized way of storing configuration data in an on-chip EEPROM. In this case the EEPROM is a 24C02, 256 Byte one. The storage of information in it is defined by the Serial Presence Detect - SPD standard. It integrates into the SMBus when plugged into a computer, and the BIOS uses the data contained to initialize memory access.
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