Notices

What is SIMLock?
SIMLock, or simlockd, is a small application written for the Nokia N900 that provides the ability for your phone to automatically lock itself if it detects that the SIM card has been changed. This is done using the phone's built in lock functionality and only requires that you have set a lock code on your phone.

What does SIMLock do?
When your phone is started up after installing SIMLock your current SIM Card's unique identifier, known as an IMSI, is stored. Each time the phone is started after that the current SIM Card's IMSI is compared to the original one. Should SIMLock find that your SIM Card's IMSI is different it will automatically lock the phone and put it into Offline Mode. Once the phone has been unlocked again SIMLock will add the current SIM Card's IMSI to the list of "allowed" IMSI numbers and it will not bother you again.

Why should I use SIMLock?
SIMLock provides an added level of security should your cellphone be stolen. While not being completely bulletproof the aim is to make it just that much more difficult for a thief to use your phone after he has stolen it. It is written to behave similarly to the functionality available in the Symbian UIQ phones of late and seems to function very well.

Where can I get it?
SIMLock is available for download here and information about the changes made to it can be found on this page.

I found a bug!
If you have managed to find a bug please feel free to send information about what happened to me at contact@sierrasoftworks.com or if you want to try your hand at fixing the problem yourself you can grab the source code from http://gitorious.org/simlockd.

Download
Install
Changes
Source Code

AppLock
This thread will now be used to discuss anything related to the development of AppLock, an application based lock for Maemo devices which has been discussed in this thread.

not sure its trustworthy but Ill give it a try, thanks

Like I said, source is up on Gitorious if you want to give it a look, just checks the IMSI number and compares it to a DB of the ones you have "authorized" before. If they aren't the same then it locks the phone using the lock DBus call. Not sure what happens if you run it without setting an unlock code though...

tried it, looks good! thanks!

Excellent, I will be releasing a new version relatively soon that fixes a few small bugs (namely, if you don't have a SIM card inserted and unlock the phone, any subsequent boots without a SIM card will not be locked, in v0.3.0 it will be.). I also plan to make it semi-configurable, at the moment it also throws the phone into offline mode, just to make it a bit harder for someone to use SSH to crack the security. I will maybe make that optional.

If you have any ideas as to how I could improve it I would love to hear them.

EDIT: Okay, the new version (0.3.0) is released. Adds a console command for the app to let you view the list of "valid" IMSI numbers and clear them if you want (i.e. start from scratch). Also, the app will now add your IMSI number to the database upon installing rather than on the phone's next boot.

The latest version can still be downloaded from the link in the first post

getting it into the repos will get it out there more too

Sounds like a good idea, to be honest though it seemed like a lot of effort for such a simple application. Will see what I can do though

please correct me if i'm wrong but isn't this feature already there by default?
i mean, without installing anything my phone already ask for lock code each time the phone starts. and i believe sshd is not even started yet until we get pass the lock screen?

anyway it's always a great work for someone giving more option to adding extra layer of security to the phone. even myself have been considering for a while whether we can encrypt our entire home directory with ecryptfs

Hey,
it would ne great to be able to start a script, to e.g. delete something (maybe cd / and then rm -r * (dont try it ). But I don't know if this is possible at the early bootstage where it is asked for the lock code?

Cheers, Blck

@figaro: Not quite, this will only force you to enter the lock code IF the SIM card has been changed. The idea being that unless someone swaps out your SIM card you won't notice it.

@blck: I could get it to do so, but it is coded in Qt so I could just force a delete of everything on the phone. That being said, I think it would be a kinda risky feature to implement for the following reasons:
1. The application cannot detect if someone enters the wrong lock code, so I couldn't do a "Enter the lock code...3 retries available" unless I coded up my own lock subsystem
2. By using the built in lock system it makes it a lot more secure than an alternative method since once it gets locked the OS handles keeping it locked rather than relying on another app to do so.

The reason for knocking it into offline mode is to make sure that if the app takes more time than necessary to load for some reason or other (bear in mind that because Upstart is used the OS will not wait for the app to finish before continuing to boot) it can still prevent the phone from being accessible later on in the boot process.

As for whether or not it is possible to run scripts during boot, absolutely.