GSM-Forum - View Single Post - Debranding

elseWestcott · 02-11-2009, 06:22

I'm not sure when it is required to use a signed VSM file. I suspect that RIM will start requiring signed VSM files in newer versions of the OS now that we know how to create our own with valid checksums.

I will leave it up to someone else to figure out and document the process of verifying the VSM signature. Of course I know that one can write a BlackBerry app that calls Branding.isDataSigned(), but I'm talking about figuring out what part of the VSM file is hashed to get the signature and what public key is used to verify it.

I've been working the last few days on adding all the remaining fields to the online VSM creator. In the process I made lots of errors and had to go back and find and fix them all. And then someone decided that it was inappropriate and my entire hosting account was deleted without any notification. That's OK though, because I have another place to host it. There are still a couple things I want to test out before I put it back online. One of those is the converson of a midi ringtone to RIM tone/duration values. I'll post when it is ready to go.

I've also completed (with some help) a BlackBerry application that retrieves all the branding information and saves it to the BlackBerry filesystem as separate files for each field. It was useful in verifying the branding info was actually written exactly as sent...even if what was sent did not make sense. i.e. loading a text file as the browser background. Of course the text file would not be displayed when running the browser, and would probably crash or at least give an error. I know that loading a text file instead of a PNG for the splash screen cause a failure to boot giving an "app error 523 reset" The BrandingInfo application is also nice to run if you would like to see what branding is currently applied to your device before messing with it. You could even back up your branding info to restore it later, although I haven't found a way to retrieve the signature for the branding data short of comparing your branding data with the 1000+ VSM files and hoping there is one that matches and getting the signature from that.

02-11-2009, 06:22	#10 (permalink)
elseWestcott Freak Poster Join Date: Jan 2009 Posts: 170 Member: 956117 Status: Offline Thanks Meter: 66	I'm not sure when it is required to use a signed VSM file. I suspect that RIM will start requiring signed VSM files in newer versions of the OS now that we know how to create our own with valid checksums. I will leave it up to someone else to figure out and document the process of verifying the VSM signature. Of course I know that one can write a BlackBerry app that calls Branding.isDataSigned(), but I'm talking about figuring out what part of the VSM file is hashed to get the signature and what public key is used to verify it. I've been working the last few days on adding all the remaining fields to the online VSM creator. In the process I made lots of errors and had to go back and find and fix them all. And then someone decided that it was inappropriate and my entire hosting account was deleted without any notification. That's OK though, because I have another place to host it. There are still a couple things I want to test out before I put it back online. One of those is the converson of a midi ringtone to RIM tone/duration values. I'll post when it is ready to go. I've also completed (with some help) a BlackBerry application that retrieves all the branding information and saves it to the BlackBerry filesystem as separate files for each field. It was useful in verifying the branding info was actually written exactly as sent...even if what was sent did not make sense. i.e. loading a text file as the browser background. Of course the text file would not be displayed when running the browser, and would probably crash or at least give an error. I know that loading a text file instead of a PNG for the splash screen cause a failure to boot giving an "app error 523 reset" The BrandingInfo application is also nice to run if you would like to see what branding is currently applied to your device before messing with it. You could even back up your branding info to restore it later, although I haven't found a way to retrieve the signature for the branding data short of comparing your branding data with the 1000+ VSM files and hoping there is one that matches and getting the signature from that.