Android noob questions

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I had a look at
SPDREM_U_01.6.5.1-73_SPU-11-PASS-10_SIGNEuropeAustraliaEMEA_USASPDRRTGB_HWp2b_Servi ce1FF_fastboot.xml
and being a Android noob I have a couple of question.
1.) Why is there a Windows executable, MotoCast-installer (~72MB) included, in the cdrom_signed file?
2.) Would it not be possible to add mods and root-kit into this firmware, e.g. system_signed, webtop_signed or any of the other xxxx_signed files, create a new MD5 checksum for the changed file to be added to SPDREM_U_01.6.5.1-73_SPU-11-PASS-10_SIGNEuropeAustraliaEMEA_USASPDRRTGB_HWp2b_Servi ce1FF_fastboot.xml?
I have seen that those xxxxx_signed files have a signature and assume that the bootloader will check these.

As I said I am a Android noob, but have a little bit of experience with previous Motorola's phones, especially the Linux based Motomagx OS used on a few models. They worked roughly this way.
I am trying to get my head around how Android phones and OS are working.

Originally Posted by Rasputin007

2.) Would it not be possible to add mods and root-kit into this firmware, e.g. system_signed, webtop_signed or any of the other xxxx_signed files, create a new MD5 checksum for the changed file to be added to SPDREM_U_01.6.5.1-73_SPU-11-PASS-10_SIGNEuropeAustraliaEMEA_USASPDRRTGB_HWp2b_Servi ce1FF_fastboot.xml?

As far as I know, those checksums are just to verify the integrity of the downloaded files, so that a bad connection or storage device can't brick your phone. I think the signatures themselves are stored in the individual partition images and verified the the bootloader at flashing-time.

The bootloader of the Motomagx phones had a RSA protection, which meant that signed codegroups could not be modified. Bizarre really as Linux based Motomagx was OpenSource and Motorola pointed the finger at the providers for that.
So I assume that a locked bootloader behaves the same way.
Once the RSA protection was cracked, we were able to modify the codegroups/firmware, even though we could leave out the signature, we still had to keep to the same byte size of most codegroups and had to keep one "security code", e.g. "00 01".
I guess this still applies now.


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