Once again Luca Dentella has published a fascinating and useful article related to our world of Arduino, and in this example he demonstrates how to use one-time passwords systems to create secure locking systems based around an Arduino. Using his library and notes, your Arduino project can sync with the Google Authenticator app (which generates the OTPs) - and from that point your project can accept and respond to the secure passwords. Luca has further demonstrated this with a simple numeric-keypad locking system.
That's a cracking example of Arduino-based security, so visit Luca's website for all the notes and downloads. And for more, we're on twitter and Google+, so follow us for news and product updates as well.
Although Luca used a software RTC implementation, he recommends a real real-time clock IC for accuracy- and a perfect example is our Maxim DS3232 real-time clock IC module:
Apart from keeping accurate time for years due to the temperature-controlled oscillator and having a tiny coin-cell for backup, it is very simple to connect to your Arduino project. A driver library allows your program to easily set or read the time and date. Perfect for clock projects, dataloggers or anything that needs to know the date and time. Furthermore it contains a digital thermometer and 236 bytes of non-volatile memory to store user settings and other data. For more information, check out the module page here.