• Introducing XDA Computing: Discussion zones for Hardware, Software, and more!    Check it out!
  • Fill out your device list and let everyone know which phones you have!    Edit Your Device Inventory

[R&D] Unlock Bootloaders

Status
Not open for further replies.
Search This thread
S

sextape

Guest
I ended up with a brick. I didn't flash aboot.img. I flashed everything but. When I rebooted, it never turned back on.

I see this USB device when connected to the computer.
Code:
Bus 001 Device 037: ID 05c6:9008 Qualcomm, Inc. Gobi Wireless Modem (QDL mode)

Does it detect it as a modem?

Qualcomm Download Mode

Sent from my SPH-D700 using Tapatalk 2
 

invisiblek

Recognized Developer
Feb 24, 2010
1,584
5,896
Minnesota
www.invisiblek.org
I ended up with a brick. I didn't flash aboot.img. I flashed everything but. When I rebooted, it never turned back on.

I see this USB device when connected to the computer.
Code:
Bus 001 Device 037: ID 05c6:9008 Qualcomm, Inc. Gobi Wireless Modem (QDL mode)

at the very least you could have jumped on irc and bounced some ideas of people before bricking it

gee, i hope the community buys you another one
lets all join together everyone!!
</sarcasm>
 

Rob_Storm

Senior Member
Sep 7, 2008
140
16
I ended up with a brick. I didn't flash aboot.img. I flashed everything but. When I rebooted, it never turned back on.

I see this USB device when connected to the computer.
Code:
Bus 001 Device 037: ID 05c6:9008 Qualcomm, Inc. Gobi Wireless Modem (QDL mode)

Do we need to get you another one? Or, can jtag help?

Please post so we can act accordingly. PM me if you are hard bricked.


Sent from my SCH-I535 using Tapatalk 2
 

AdamOutler

Retired Senior Recognized Developer
Feb 18, 2011
5,224
9,811
Miami, Fl̨̞̲̟̦̀̈̃͛҃҅͟orida
at the very least you could have jumped on irc and bounced some ideas of people before bricking it

gee, i hope the community buys you another one
lets all join together everyone!!
</sarcasm>

Enough with the off topic guys. I have it covered. Basically this only means I'm out of commission for the night thanks to Josh at MobileTechVideos.com :)
 

incubus26jc

Inactive Recognized Developer
Feb 12, 2009
4,094
3,569
Illinois
at the very least you could have jumped on irc and bounced some ideas of people before bricking it

gee, i hope the community buys you another one
lets all join together everyone!!
</sarcasm>

I'm not sure that comment was necessary. I always have respected your work especially with this phone. But to basically say that you hope the community doesn't get him a new phone because you feel it was a preventable brick is ridiculous. I feel like the community would do the same for you if you had bricked. Please if I have misunderstood you, ignore this post and I apologize.

Sorry for off topic.


Enough with the off topic guys. I have it covered. Basically this only means I'm out of commission for the night thanks to Josh at MobileTechVideos.com :)

Great News
 
Last edited:

LLStarks

Senior Member
Jun 1, 2012
1,531
576
I just don't think it's right how we let random files distract us from safer research.

If we didn't have JTAG at the ready, everything we were planning to do with the schematics would've been compromised.
 
  • Like
Reactions: E:V:A and cordell12

prdog1

Senior Member
Mar 10, 2012
9,098
5,460
Houston, Texas
I just don't think it's right how we let random files distract us from safer research.

If we didn't have JTAG at the ready, everything we were planning to do with the schematics would've been compromised.[/QUOT


Josh @ MobileTech got your back as well as all of us in Texas. That is what we do. We stand behind whatever it takes to win and never quit. We also back our friends in Louisiana. Let us know what you need Adam. ;)

Mods can remove as as soon as posted.
 

AdamOutler

Retired Senior Recognized Developer
Feb 18, 2011
5,224
9,811
Miami, Fl̨̞̲̟̦̀̈̃͛҃҅͟orida
So, I decided to work with the new device which is enumerating...
Here's the lsusb
Code:
Bus 001 Device 040: ID 05c6:9008 Qualcomm, Inc. Gobi Wireless Modem (QDL mode)
here's the dmesg
Code:
[181577.769482] usb 1-1.3: new high-speed USB device number 39 using ehci_hcd
[181577.862963] qcserial 1-1.3:1.0: Qualcomm USB modem converter detected
[181577.863127] usb 1-1.3: Qualcomm USB modem converter now attached to ttyUSB0

I connected up with minicom and I was not able to talk to it at all. I received no response. So I decided to poke around a bit more on other things... It appears that QDL mode is like Qualcomm's version of Odin Download Mode.

I found a tool called "gobi_loader" which is supposed to communicate with this QDL mode. I'm running into a problem where it does not recognize the format of the firmware folder I am feeding it. I am trying to find out more about this.

This is some great news though. It could satisfy goal #1 as stated in the OP once we figure it out.
 
S

sextape

Guest
So, I decided to work with the new device which is enumerating...
Here's the lsusb
Code:
Bus 001 Device 040: ID 05c6:9008 Qualcomm, Inc. Gobi Wireless Modem (QDL mode)
here's the dmesg
Code:
[181577.769482] usb 1-1.3: new high-speed USB device number 39 using ehci_hcd
[181577.862963] qcserial 1-1.3:1.0: Qualcomm USB modem converter detected
[181577.863127] usb 1-1.3: Qualcomm USB modem converter now attached to ttyUSB0

I connected up with minicom and I was not able to talk to it at all. I received no response. So I decided to poke around a bit more on other things... It appears that QDL mode is like Qualcomm's version of Odin Download Mode.

I found a tool called "gobi_loader" which is supposed to communicate with this QDL mode. I'm running into a problem where it does not recognize the format of the firmware folder I am feeding it. I am trying to find out more about this.

This is some great news though. It could satisfy goal #1 as stated in the OP once we figure it out.

So the brick was kinda a good thing

Sent from my SPH-D700 using Tapatalk 2
 

alquimista

Senior Member
Mar 20, 2008
218
118
Los Angeles
So, I decided to work with the new device which is enumerating...
Here's the lsusb
Code:
Bus 001 Device 040: ID 05c6:9008 Qualcomm, Inc. Gobi Wireless Modem (QDL mode)
here's the dmesg
Code:
[181577.769482] usb 1-1.3: new high-speed USB device number 39 using ehci_hcd
[181577.862963] qcserial 1-1.3:1.0: Qualcomm USB modem converter detected
[181577.863127] usb 1-1.3: Qualcomm USB modem converter now attached to ttyUSB0

I connected up with minicom and I was not able to talk to it at all. I received no response. So I decided to poke around a bit more on other things... It appears that QDL mode is like Qualcomm's version of Odin Download Mode.

I found a tool called "gobi_loader" which is supposed to communicate with this QDL mode. I'm running into a problem where it does not recognize the format of the firmware folder I am feeding it. I am trying to find out more about this.

This is some great news though. It could satisfy goal #1 as stated in the OP once we figure it out.

How did you get a new device so fast?

More importantly, please explain how you are setup right now to talk to the device? Is it the same modem setup that you explained before?

Lastly, my ignorance is really gleaming here, what do you mean by "enumerating"?

Sorry, I'm just trying to mimic what you are doing right now to see if I can be of any help.

Ta,
ALQI

Sent from my SCH-I535 using xda app-developers app
 

E:V:A

Inactive Recognized Developer
Dec 6, 2011
1,449
2,214
-∇ϕ
Constructive Criticism

Constructive Criticism
As I have been on holiday and it's been raining here quite a bit, I have had a
lot of time to spend on this project. I have been posting all I have found and
tried to clarify this material so that other people who is also working on this,
can be kept up to date and informed, and help out. However, I feel that I'm just
dumping all this information into a black hole, as I don't get or see any
(or very little) constructive and useful feedback, to my questions and posts etc.
So I must ask you all the following.

Is anybody actually working on this?

What does it mean "to be working on" this? It means that you are actively doing
one or more of the following:

a) Answering relevant questions related to this topic and posted in this thread.
b) Finding, reading and sharing information that is related to this topic.
c) Come up with new, well formulated and well though through ideas about how to get "unlocked".
(Search first! You're probably not the first one who have thought about this.)
d) Provide technical documentation, inside skills or other relevant knowledge to this topic.
e) Provide experimental results answering some clearly defined problem/question. For example:

Q: So you want to verify that after reboot, the phone does W when writing to register X.
A: So, you wrote to register X by using this command Y, with the resulting output Z.
Then after reboot, you got W as shown. Question confirmed.


f) You are not blindly performing senseless experiments with the only result
of bricking your device and not having learned anything.
g) You are asking for and listening to good advice from reliable sources,
and if you are a reliable source, you are happy to share and provide
evidence for your advice.


In the last couple of pages there have been some completely senseless posts
about flashing some random firmware from a completely different device, and
thinking that we would actually learn anything. Let's stop this insanity now!
(Or I'll have to leave this thread for good, to keep my own!) It's not very
Zen to do something extreme without any well founded thought behind it,
especially when your going against the well established ideology.


Case Study

When Adam bricked his phone, I really started to get upset. It was a complete
waste of time, effort and motivation. And I was wondering why I bother with this
at all, and the head-line question undoubtedly entered my mind. At least
based on the information I had at the time. There are many many reasons why this
would not work, and we were several reliable people telling him not to do it.
(So why did he?) Then after seeing what he actually did, we could have predicted
with 100% certainty that it would be at least be soft-bricked. Some reasons why
this case was particularly bad:

1) Overwriting a file system you are currently using will kill you!
(This can only be done in certain circumstances like in Linux, which has
this capability where you can transfer execution from disk based to memory
based. But Android is only memory based and very complicated at that,
as code execution occurs in several different memories and processors
at different times.)
2) No consideration seem to have been taken that Odin/Heimdal (most likely)
put the phone in a special mode for flashing firmware. (See 1) In any
case, there is a good reason why people generally doesn't just "dd"-flash
their devices. That reason is that Odin/Heimdal probably make use of the
special Qualcomm communication protocol(s) QMI or DM as discussed here.
3
) No consideration was taken to the fact that the firmware belonged to a
completely different device and need to be signed. (At least nobody provided
any information to prove it was the same or even similar enough.)
4
) No consideration was taken that the firmware was of a different size
than the original.
5
) No consideration was taken of the previously posted Secure Boot procedure and
information.
6
) No consideration of good and well founded advice, from reliable sources.
7
) Not sharing his initial thoughts (if any), nor the expected results.


This is very demotivating, although it is nice and sometimes inspiring
to see that someone is actually taking some action. BUT...

Let's not be(come) headless chickens!


PS. There are many more case examples, but Adam know I respect his work and
can handle the heat, so I just used his case as a recent example...

 

AdamOutler

Retired Senior Recognized Developer
Feb 18, 2011
5,224
9,811
Miami, Fl̨̞̲̟̦̀̈̃͛҃҅͟orida
Constructive Criticism
1) Overwriting a file system you are currently using will kill you!
(This can only be done in certain circumstances like in Linux, which has
this capability where you can transfer execution from disk based to memory
based. But Android is only memory based and very complicated at that,
as code execution occurs in several different memories and processors
at different times.)
2) No consideration seem to have been taken that Odin/Heimdal (most likely)
put the phone in a special mode for flashing firmware. (See 1) In any
case, there is a good reason why people generally doesn't just "dd"-flash
their devices. That reason is that Odin/Heimdal probably make use of the
special Qualcomm communication protocol(s) QMI or DM as discussed here.]
This isn't a filesystem being used. The bootloaders are loaded into memory and then executed at startup. Once the kernel is loaded, everything prior is irrelevant.

3) No consideration was taken to the fact that the firmware belonged to a
completely different device and need to be signed. (At least nobody provided
any information to prove it was the same or even similar enough.)
4
) No consideration was taken that the firmware was of a different size
than the original.

Take note of the fact that I commented out the aboot. It was not flashed because it was advised that I do not flash that partition.

5) No consideration was taken of the previously posted Secure Boot procedure and
information.
6
) No consideration of good and well founded advice, from reliable sources.
7
) Not sharing his initial thoughts (if any), nor the expected results.
I shared all my initial thoughts. It was risky and I was willing to take the risk to verify this firmware would or would not work. I have the tools to recover so i'm not worried about the risks.

I'd do it again if another reputable source came up with an experimental firmware to flash. Ask yourself this, who else is in a position to test that sort of thing?

Anyways, as I stated above, I've now got a QDL device to work with.
 
Last edited:

Ralekdev

Retired Senior Recognized Developer
Sep 4, 2010
32
384
I guess it might be helpful to explain why we can't just flash other devices' bootloaders.

Every bootloader image has 3 sections: code, signature, and a certificate chain. These are normal DER/ASN.1 certs (up to 3), nothing all that special except the first certificate has some extra properties. One of those properties is a hardware identifier for our specific model (as far as I know). So when the PBL is attempting to authenticate the SBL1, it compares that hardware id with it's own. If it doesn't match, it doesn't load the SBL1 and the PBL goes into error recovery mode. But say the hardware IDs were the same, now you have to consider whether the key in the PBL will be able to verify the certificates. If it can't, we're right back in the PBL error handler.

The signature section is 256 bytes that will decrypt to 0x0001FFFF, followed by 248 more 0xFF, and finally 0xFFFFFF00 as long as you haven't tampered with any part of the header, code section, or certain parts of the attestation certificate. Failing to decrypt correctly will once again land you in the PBL error handler.

Note the above steps are taken in every part of the PBL -> SBL1 -> SBL2 -> TZ -> RPM -> SBL3 -> ABOOT chain, so you can't just skip one or try to trick it.

Any of those reasons could be responsible for the brick. Those reasons are also why I'm not very optimistic for the developer edition phone, whenever it comes out. All they'd need to do was just change the hardware id or pbl key and we couldn't use it.


So say you did flash another device's bootchain and you're stuck with a "brick", what do you do?

Because Adam's device still turns on and registers as something to the computer, I think we can conclude that the emergency download feature has not been disabled. Otherwise, the device would just turn off as soon as it hit the error.

Normally, the phone tries to boot from SDC1, the internal card. In his case that's hosed, so it'll move to trying SDC3, the external card. So if my thinking is correct, if we format the external card to match the layout of the internal card (not the whole thing, you'd only need up to aboot to get odin capability back), then it would attempt a normal boot from the external card. You'd just have to have the partitions have the correct GPT guids, since that's how the loaders locate the next in the chain.

Another possible way to recover is through the QDL mode his phone is in now. https://www.codeaurora.org/patches/quic/gobi/Gobi3000/GobiAPI_2012-07-10-0919.tar.gz has some code for interacting with devices in QDL mode, however we need to find out the correct values for the eQDLImageType enum for our device (Core/QDLEnum.h). Currently it's using terminology from secboot2, whereas we're on secboot3. The correct values would most likely be found in the PBL, since that's what's running the QDL mode. We won't know if this method works completely until we can get ours hands on a dump of the PBL

That's proven to be quite tricky, and it may take a hardware method to get that dump.
I've tried using DM mode, but unfortunately samsung removed the all of the diagnostic commands that let you dump memory (DIAG_PEEKB_F and kin).
I then tried sending the DIAG_DLOAD_F command to switch it to DMSS mode, which didn't work because they made that command reboot the phone.
In DMSS mode I could have potentially uploaded some shellcode to dump the region. Arbitrary memory reads in DMSS mode looked restricted to certain regions, but the writes weren't, so I could have written shellcode to some unused ram segment, then there's a command to start execution at a specific address.

The PBL should be located at 0x00000000 according to the docs if anyone wants to give it a shot.


Apologies for the length and utter lack of formatting on this post, but I wanted to jot that down before heading to bed.
 

Ralekdev

Retired Senior Recognized Developer
Sep 4, 2010
32
384
Ralekdev, did you try the 'viewmem' utility?

Hadn't seen that before, but yeah it appears to have gotten at least part of it. I can't say whether it's the full thing because there are some references in the 0x20000 range but the rpm firmware is loaded there after the pbl is through which could mean the original data was overwritten. I'll take a closer look later on today
 

AdamOutler

Retired Senior Recognized Developer
Feb 18, 2011
5,224
9,811
Miami, Fl̨̞̲̟̦̀̈̃͛҃҅͟orida
Hadn't seen that before, but yeah it appears to have gotten at least part of it. I can't say whether it's the full thing because there are some references in the 0x20000 range but the rpm firmware is loaded there after the pbl is through which could mean the original data was overwritten. I'll take a closer look later on today

There is an article I posted on the front page of xda today which outlines a data forensics tool called 'LImE'. It is a loadable kernel module which will make a complete dump of all memory on a device. You may be interested in it.
 
Last edited:
Status
Not open for further replies.

Top Liked Posts

  • There are no posts matching your filters.
  • 561
    Verizon GS3 is now Bootloader UNLOCKED.
    We now have access to an unsecure bootloader. This was leaked by an African-Canadian Sock Monkey.

    Let me make this clear. If Samsung updates your device's bootloaders, using this tool could potentially brick your device. Once you apply this, never accept a factory update without first flashing the Odin Packages in the Original Post of this thread. As a general rule, you want to be the last guy to apply any Samsung update. Run custom.

    As of the date of this posting, this works great on Linux and it should work wonderfully on Mac too. NOTE: this may work on windows, but please, windows users.. learn to use your computer before you ask questions on XDA-Developers. This is one-click on Linux and Mac every darn time. If you're using Windows, I recommend downloading Windows Ubuntu Installer(WUBI) to install Ubuntu from within Windows.

    Download
    http://d-h.st/ypJ


    Instructions:
    1. Open this file
    2. Select Root with DebugFSRoot and Do It
    3. Select Flash Unsecure Aboot and Do It
    4. Use Odin or CWM to flash kernels to your device

    1zqwmlc.png

    To flash from device without the above tool:
    • root your device
    • Download this link to your /sdcard/Downloads/ folder: http://d-h.st/Piq
    • Type this in the terminal emulator
      Code:
      su -c dd if=/sdcard/Downloads/aboot.img of=/dev/block/mmcblk0p5

    This was tested with a Sprint kernel flashed via Odin. Although the Sprint kernel caused the device to have a blank screen due to hardware incompatibility, it's more than enough for a proof-of-concept. Stock bootloaders will not let you flash improper kernels with Odin and will cause the device not to boot. This corrects the problem. I'll leave implementation to other developers. If you feel uncomfortable flashing this on your own, wait for your favorite kernel developer to release something.

    Note to developers: This CASUAL package contains everything you need. A jar can be opened as a zip file. CASUAL format sticks all scripts in the /SCRIPTS/ folder. You can obtain all files needed from within this package, then repackage them into CWM format. In order to avoid a mass brick fest, please apply an assert to your CWM scripts to verify ro.build.version.incremental and do not allow updates past what has been tested. As of the time of this writing I535VRALG7B is safe.

    With the unlock of the GS3, this thread is locked. There will be no victory dancing in here. Move along to General or something. This thread will lie dormant until it is needed again in the future. Ralekdev will be releasing another exploit in the future as soon as this one stops working. Feel free to review what was learned until then.

    P.S. Sorry to those who I have offended by having posts removed. I'm also sorry to those who had their intelligence insulted before I had both of our posts removed. I hope you understand that in 6 months from now when everyone forgets about this thread but needs to catch back up, the information will still be right here in condensed format.
    173
    Rules:
    Do not post in here unless you have something constructive to say. "Thanks", "Hey this is wonderful", and any other comments like that are not wanted. They take up space and make it more difficult to find information. I'm requesting that this thread be heavily moderated. In order to work efficiently, information density must be kept high. We are all guilty of adding in a few off-topic sentances from time-to-time, but this thread is strictly business and I expect the moderators to moderate me as well.

    What is this?
    This is the place where we can research and develop a method to unlock the bootloader of the Verizon Galaxy SIII. Hopefully, this will be development at its finest.


    Why not just buy a developer edition
    GTFO! Not a single person got started developing by buying a developer phone. They started developing because they were unhappy with the features of their device and wanted something better. They wanted something more. This developer phone is a tax on developer innovation. We do not stand for that. We will break the security and we will enable XDA-Developers to do what they do best.

    Until security is broken and available for everyone, this device will get updates last, users will be unhappy because there are no additional features and Samsung violates the spirit of Open Source and copyright laws. Take a look at the bottom line of GPL-Violations.org FAQ located here: http://gpl-violations.org/faq/sourcecode-faq.html


    What are the goals?
    • Attain a bootloader recovery - 75% JTAG (the extra 25% will be for a user-friendly method)
      The Galaxy S3 is bootable from SDCard. In case of emergency this is needed. We need to verify that this works on the Verizon GS3 to bring up Odin. This will set up infrastructure for research.
    • Attain a full stock restoration via Odin or Heimdall - 90%
      For use with Odin3.
      Bootloader - BOOTLOADER_I535VRALF2_618049_REV09_user_low_ship.tar.md5 - 1.97 MB - Thanks nbsdx
      PDA - SCH-I535_VZW_1_20120705143513_fti2qg2lmf.zip
      NEED CSC PACKAGE (MODEM, PARAMS and Other Miscellaneous partitions). This is enough to recover a device though.
      To include bootloaders and recovery to a working and stock condition with the EMMC wiped entirely. Heimdall is a work in progress for this device. This will complete the infrastructure needed for research.
    • Collect information
      This will be the longest and most difficult part of this development. The information provided by Qualcomm is not readily available. Samsung is notoriously secretive about their bootloaders. Mainly we, as a community, will generate information. Please post any relevant datasheets, theory-of-operation, or manuals which you can find.
    • Provide a way to remove security checks from Odin3.] 100% - insecure aboot.img which may break in the future
      By removing security checks from Odin3 on the computer or the Loki daemon on the device we can flash anything through Odin or Heimdall.
    • Provide a way to bypass security checks within bootloaders. 200% we have two exploits, only one has been released.
      This is the ultimate goal. Once we can bypass the security checks, kernels can be flashed giving us the control required to develop


    Initial information
    [BOOTLOADER] Locked bootloader research and news: http://forum.xda-developers.com/showthread.php?t=1756919


    My own research

    SBL1 is the first booting partition. Qualcomm provides the Modem partition so it comes first on the EMMC. SBL1 is the first bootloader and that is specified by Qualcomm standards. Qualcom mmake sthe primitive bootloader and allows their customers (Samsung) to make a Secondary bootloader. Samsung chose to use three secondary bootloaders.

    The following 0p* are located in /dev/block/mmcblk*

    0p1 = modem
    Built by se.infra
    HUDSON_GA_D2_USA-VZW-HARDKEY-PROD-USER
    I take this to mean this Qualcomm modem was built in Hudson Georgia.
    I was not able to find signatures on this block :). This does NOT mean that there are no signatures on this block. The file is 33 megs. The file is unencrypted.
    The modem uses the BLAST Kernerl ver : 02.04.02.02.00 Unfortunately we need someone who speaks French(???) to understand how this works http://blast.darkphpbb.com/faq.php
    Judging by the contents of this file, it is an operating system of it's own including keyboard, mouse and a lot of debugging information. We need to find out more about the BLAST Kernel and this partition.


    Samsung Proprietary partitions SBL1,2,3
    Overall I'm not entirely familiar with this new 3 SBL setup. If someone could help me out, that would be great. This 3 SBL setup looks like they tried to adapt (slopily) their IBL+PBL+SBL setup to the Qualcomm and added overhead.

    op2=sbl1
    This block is signed by Samsung, we will not be able to modify it.
    Some Strings we expect to see on UART are:

    0p3=sbl2
    This block is signed by Samsung, we will not be able to modify it.

    Some of the strings we may see over UART are:
    Code:
    RPM loading is successful.
    cancel RPM loading!
    SBL2, End
    SBL2, Delta
    .sbl2_hw.c
    sbl2_hw_init, Start
    sbl2_hw_init, Delta
    sbl2_hw_init_secondary, Start
    h/w version : %d
    sbl2_hw_init_secondary, Delta
    .SBL2, Start
    scatterload_region & ram_init, Start
    .scatterload_region & ram_init, Delta
    .sbl2_mc.c
    sbl2_retrieve_shared_info_from_sbl1, Start
    .sbl2_retrieve_shared_info_from_sbl1, Delta

    0p4=sbl3
    This block is signed by Samsung, we will not be able to modify it.

    Possibly useful information:
    SVC: R1-R14
    FIQ:R13-R14
    IRQ:R13-R14
    UND:R13-R14
    ABT:R13-R14
    SYS:R13-R14

    This block appears to be a full OS of its own. I'm not sure of its purpose.

    op5= aboot
    This block is signed by Samsung, we will not be able to modify it

    This block contains HTML information. It would appear that it is possible to put the device into a mode where it will provide a webserver which displays state information.

    This block appears to be a complete operating system

    This block contains the Loke Daemon which communicates with Odin3.


    0p6= rpm
    This block is signed by Samsung we will not be able to modify it

    0p7= boot
    This is the kernel. There are several things we can do here... I belive this package itself is not signed, but the zImage itself is... here is the bootimg.cfg file

    Code:
    [email protected]:~/Desktop/VZWGS3$ cat ./bootimg.cfg 
    bootsize = 0xa00000
    pagesize = 0x800
    kerneladdr = 0x80208000
    ramdiskaddr = 0x81500000
    secondaddr = 0x81100000
    tagsaddr = 0x80200100
    name = 
    cmdline = console=null androidboot.hardware=qcom user_debug=31

    It may be possible to use that cmdline variable as an exploit.




    0p8= tzTrust Zone
    0p9= pad
    0p10= param -boot mode parameters - this could be a potential exploitation point.
    0p11= efs -serial numbers
    I've honestly got no clue about most of the following partitions.
    0p12= modemst1
    0p13= modemst2
    0p14= system - Android stuff
    0p15= userdata - App Stuff
    0p16= persist
    0p17= cache - Storage for updates
    0p18= recovery - recovery partition
    0p19= fota
    0p20= backup
    0p21= fsg
    0p22= ssd
    0p23= grow

    External UART log from initial power up:
    Code:
    [1630] AST_POWERON
    [    0.000000] heap->name mm, mb->start c0000000
    [    0.000000] Reserving memory at address ea000000 size: 100000
    [    0.000000] sec_dbg_setup: [email protected]
    [    0.000000] sec_dbg_setup: secdbg_paddr = 0x88d90004
    [    0.000000] sec_dbg_setup: secdbg_size = 0x40000
    [    0.000000] etb_buf_setup: [email protected]
    [    0.000000] etb_buf_setup: secdbg_paddr = 0x8fffb9c0
    [    0.000000] etb_buf_setup: secdbg_size = 0x4000
    [    0.174515] rdev_init_debugfs: Error-Bad Function Input
    [    0.174881] AXI: msm_bus_fabric_init_driver(): msm_bus_fabric_init_driver
    [    0.176957] sec_debug_init: enable=0
    [    0.177475] ec_debug_nit: restrt_reason: 0xdf0085c
    [    .216358] msm8960_iit_cam:292]settingdone!!
    [    0.25006] i2c 2c-14: Inalid 7-bi I2C addrss 0x00
        0.25237] i2c ic-14: Can' create evice at x00
    [   0.252220]i2c i2c-1: Failed o registeri2c clien cmc624 t 0x38 (-6)
    [    .252250] 2c i2c-19:Can't crete deviceat 0x38
        0.25433] rdevinit_debufs: Error-ad Functin Input
        0.25222] max892 19-006: DVS mode disabledbecause VD0 and VI1 do not ave prope control.
    [    0.79536] ms_etm msm_tm: ETM tacing is ot enable beacaussec_debug s not enaled!
    [   0.284449 smd_chanel_probe_orker: alocation tble not iitialized
                                                                      [    0.38766] pm_untime: fil to wak up
    [   0.362032]hdmi_msm dmi_msm.1 externalcommon_stte_create sysfs grup de39e68                                                                   
    [    0362673] Iside writback_drivr_init                                                                                                         
    [   0.36275] Insidewritebackprobe                                                                                                               
    [    1.244803] TZCOM: unable to get bus clk                                                                                                     
    [    1.431680] cm36651_setup_reg: initial proximity value = 3                                                                                   
    [    1.549671] msm_otg msm_otg: request irq succeed for otg_power                                                                               
    [    1.566702] mms_ts 3-0048: [TSP] ISC Ver [0xbb] [0x20] [0x20]                                                                                
    [    1.571341] mms_ts 3-0048: [TSP] fw is latest. Do not update.                                                                                
    [    1.583488] [__s5c73m3_probe:3818] S5C73M3 probe                                                                                             
    [    1.587089] [s5c73m3_sensor_probe_cb:3793] Entered                                                                                           
    [    1.591942] [s5c73m3_i2c_probe:3675] Entered                                                                                                 
    [    1.596123] [s5c73m3_init_client:3381] Entered                                                                                               
    [    1.600579] [s5c73m3_i2c_probe:3695] Exit                                                                                                    
    [    1.604608] [s5c73m3_sensor_probe:3726] Entered                                                                                              
    [    1.609095] [s5c73m3_spi_init:226] Entered                                                                                                   
    [    1.613154] [s5c73m3_spi_probe:191] Entered                                                                                                  
    [    1.617335] [s5c73m3_spi_probe:201] s5c73m3_spi successfully probed                                                                          
    [    1.623561] [s5c73m3_sensor_probe :  3749] Probe_done!!                                                                                      
    [    1.672638] mmc0: No card detect facilities available                                                                                        
    [    1.682984] aat1290a_led_probe : Probe                                                                                                       
    [    1.693850] msm_soc_platform_init                                                                                                            
    [    1.697298] msm_afe_afe_probe                                                                                                                
    [    1.843064] msm_asoc_pcm_new                                                                                                                 
    [    1.849748] msm_asoc_pcm_new                                                                                                                 
    [    2.023134] set_dload_mode <1> ( c00176d4 )                                                                                                  
    [    2.052220] cypress_touchkey 16-0020: Touchkey FW Version: 0x06                                                                              
    [    2.123851] init: /init.qcom.rc: 466: invalid command '/system/bin/log'                                                                      
    [    2.129620] init: /init.qcom.rc: 573: ignored duplicate definition of service 'sdcard'                                                       
    [    2.137402] init: /init.qcom.rc: 586: ignored duplicate definition of service 'ftm_ptt'                                                      
    [    2.145490] init: /init.target.rc: 73: ignored duplicate definition of service 'thermald'                                                    
    [    2.154677] init: could not open /dev/keychord                                                                                               
    [    2.239951] init: Device Encryption status is (0)!!                                                                                          
    [    2.243705] init: [disk_config] :::: fsck -> /dev/block/mmcblk0p15 (ext4):::::                                                               
    [    2.251823] init: [disk_config] ext_check -> /system/bin/e2fsck -v -y /dev/block/mmcblk0p15                                                  
    [    2.588921] init: [disk_config] ext_check ->ok                                                                                               
    [    2.611597] init: [disk_config] :::: fsck -> /dev/block/mmcblk0p17 (ext4):::::                                                               
    [    2.617762] init: [disk_config] ext_check -> /system/bin/e2fsck -v -y /dev/block/mmcblk0p17                                                  
    [    2.655333] init: [disk_config] ext_check -> ok                                                                                              
    [    2.664947] init: [disk_config] :::: fsck -> /dev/block/mmcblk0p11 (ext4):::::                                                               
    [    2.671081] init: [disk_config] ext_check -> /system/bin/e2fsck -v -y /dev/block/mmcblk0p11                                                  
    [    2.704532] init: [disk_config] ext_check -> ok                                                                                              
    [    3.259056] init: cannot find '/system/etc/install-recovery.sh', disabling 'flash_recovery'                                                  
    [    3.270471] init: cannot find '/system/bin/dmbserver', disabling 'dmb'

    External UART log from battery-pull and reinsert
    Code:
    [1630] AST_POWERON
    [    0.000000] heap->name mm, mb->start c0000000
    [    0.000000] Reserving memory at address ea000000 size: 100000
    [    0.000000] sec_dbg_setup: [email protected]
    [    0.000000] sec_dbg_setup: secdbg_paddr = 0x88d90004
    [    0.000000] sec_dbg_setup: secdbg_size = 0x40000
    [    0.000000] etb_buf_setup: [email protected]
    [    0.000000] etb_buf_setup: secdbg_paddr = 0x8fffb9c0
    [    0.000000] etb_buf_setup: secdbg_size = 0x4000
    [    0.174484] rdev_init_debugfs: Error-Bad Function Input
    [    0.174851] AXI: msm_bus_fabric_init_driver(): msm_bus_fabric_init_driver
    [    0.176926] sec_debug_init: enable=0
    [    0.177445] sc_debug_iit: restat_reason  0xdf0086c
    [    0216206] [sm8960_int_cam:299]setting one!!
    [   0.217915 select_req_plan:ACPU PVS:Nominal
        0.25206] i2c ic-14: Invaid 7-bit 2C addres 0x00
    [   0.25207] i2c i2-14: Can'tcreate deice at 0x0
    [    0252250] 2c i2c-19 Failed t register 2c clientcmc624 at0x38 (-16
    [    0252250] ic i2c-19: an't creae device t 0x38
    [   0.25243] rdev_iit_debugs: Error-Bd Functio Input
    [   0.25292] max895 19-0060:DVS modesdisabled ecause VI0 and VID do not hve propercontrols.
                                                                                               [    0.29536] msmetm msm_em: ETM trcing is nt enable!
    [    0.35797] pm_rntime: fal to wakeupllcation tale not intialized
    [    .362093] dmi_msm hmi_msm.1:external_ommon_stae_create:sysfs grop de39e60                                                                   
    [    0.62734] Inide writeack_driverinit                                                                                                         
    [   0.36285] Inside riteback_robe                                                                                                               
    [    1.244803] TZCOM: unable to get bus clk




    possible exploitations
    Possible entry point MODEM - Someone with a JTAG setup test viability of modifying a single byte on /dev/block/mmcblk0p1
    Possible entry point PARAMS - Samsung stores their boot parameters in PARAMS partition. It may be possible to modify PARAMS for insecure boot
    Possible entry point BOOT - Modify CMDLINE parameter to load information from another location.
    Possible entry point BOOT - We may be able to shove an insecure bootloader into memory, boot into that, and then use the recovery partition as our kernel partition. Bauwks 2nd U-Boot. U-Boot is available for the Exynos 4412, we need to find one for Qualcomm.
    Possible entry point SYSTEM - It may be possible to use a 2nd init hack from this partition to load custom kernels into memory and reboot the kernel.


    Current tasks
    What do all of these partitions do?
    Do we have a SDCard based recovery?
    Where can we find an Odin3 CSC Flash?
    Testing methods above is required
    96
    I have heard, but do not know, that there may be plans to get one of the developer phones into Adam's hands to extract from. That may provide insight into how to disable Qualcomm Secure Boot no? Anyone care to shed some light on if this is still planned or not? Thanks

    I don't need another device. I want all of the partitions from a developer device and I'd like to work with someone who has one. Remote access via "WirelessADB" and the device set to be in the "DMZ" of a router would be sufficient for all tests I would need to do.

    Just as an update, I'm slowly getting back to work. For those who were wondering, I packed up everything and moved. I have my stuff 90% set up. I'm just getting back on it. I'm working on compiling all of the Verizon GS3 exploits into a single CASUAL one-click package. Root, recovery, Busybox, Basic Hacking Tools.

    Once I've got a CASUAL package put together I'll go through and read this thread again from start to finish and figure out what needs work... my mind is totally off-topic right now after a move. Time to get back to work. I hope to have some big news at the end of next week.
    85
    It's been a few days so I wanted to give an update on the signature check on boot.img

    As has been previously guessed, everything important in boot.img is included in the signature check

    page_size is always 0x800 since we're using emmc boot

    hash_size = 0x800 (read the first page with the boot_img_header)
    hash_size += page_size * ((page_size + ramdisk_size - 1) / page_size)
    hash_size += page_size * ((page_size + kernel_size - 1) / page_size)
    hash_size += page_size * ((page_size + second_size - 1) / page_size)

    For the stock boot.img, this should come out to be 0x573000, so the first 0x573000 bytes in boot.img are checked.

    These bytes are then SHA1 hashed and passed to the verification function

    After hash_size bytes is a series of 0x100 byte blocks that will be passed to the verification function (img_sig_data parameter below)

    The verification function uses the following structure

    Code:
    struct sig_ctx_t {
    	int count;
    	int seed[65];
    	int subcheck_seed[64]; // possibly a modulus
    }

    This sig_ctx is located in aboot.img at file offset 0x12642C in VRALF2 and VRALG1 (It'll start with bytes 0x40, 0x00, 0x00, 0x00)

    I've cleaned up the first function a bit from what IDA/Hex-Rays spit out, but the second function I haven't simplified as much

    Code:
    int signature_check_data(sig_ctx_t *sig_ctx, char *img_sig_data, signed int signature_len, char *sha1_of_contents) {
    
    	int* img_ofs_0x100 = (int*)(img_sig_data + 0x100);
    	int* img_ofs_0x200 = (int*)(img_sig_data + 0x200);
    	int* img_ofs_0x300 = (int*)(img_sig_data + 0x300);
    	int* img_ofs_0x400 = (int*)(img_sig_data + 0x400); // Temporary storage
    
    	// Copy 0x0 block to 0x100
    	memcpy(img_ofs_0x100, &img_sig_data[0], signature_len);
    
    	// ofs_0x200 is filled with byte-swapped ints from img_ofs_0x100
    	for (int i = 0; i < sig_ctx->count; i++) {
    		img_ofs_0x200[i] =  htonl(img_ofs_0x100[sig_ctx->count - 1 - i]);
    	}
    
    	// subcheck(sig_block *block, int *output, int *input1, int *input2)
    	// multiplication maybe?
    	signature_subcheck(sig_ctx, img_ofs_0x300, img_ofs_0x200, sig_ctx->subcheck_seed);
    	signature_subcheck(sig_ctx, img_ofs_0x400, img_ofs_0x300, img_ofs_0x300);
    	signature_subcheck(sig_ctx, img_ofs_0x300, img_ofs_0x400, img_ofs_0x200);
    
    	if ( sig_ctx->count )
    	{
    		count_minus_1 = sig_ctx->count - 1;
    		v18 = img_ofs_0x300[sig_ctx->count - 1];
    		v19 = sig_ctx->seed[sig_ctx->count]; // seed[64]
    		// v19 = *(&sig_ctx->count + sig_ctx->count + 1);
    		if ( v18 >= v19 )
    		{
    			if ( v18 == v19 )
    			{
    				for (int i = 0; i < sig_ctx->count; i++) {
    					int v22 = img_ofs_0x300[sig_ctx->count - 1 - i];
    					int v23 = sig_ctx->seed[sig_ctx->count - 1 - i];
    					if (v22 < v23) {
    						goto LABEL_18
    					}
    				}
    			}
    			if ( sig_ctx->count > 0 )
    			{
    				int carry = 0;
    				for (int i = 0; i < sig_ctx->count; i++) {
    					uint64 temp = img_ofs_0x300[i] - (uint64)sig_ctx->seed[i + 1];
    					img_ofs_0x300[i] = img_ofs_0x300[i] - sig_ctx->seed[i + 1] + carry;
    					carry = (int)(temp >> 32); // get high 32 bits
    				}
    			}
    		}
    
    		LABEL_18:
    		// Store the calculation back into img_ofs_0x100
    		for (int i = 0; i < sig_ctx->count; i++) {
    			int val = img_ofs_0x300[sig_ctx->count - 1 - i];
    			char* dest = &img_ofs_0x100[i];
    
    			dest[0] = (val & 0xFF000000) >> 24;
    			dest[1] = ((val & 0x00FF0000) >> 16) & 0xFF;
    			dest[2] = ((val & 0x0000FF00) >> 8) & 0xFF;
    			dest[3] = (val & 0xFF);
    		}
    
    		if (memcmp(img_ofs_0x100, sig_check_compare_result, 236)) // sig_check_compare_result is a char[236] with the first 2 bytes 0x00, 0x01, and the rest 0xFF
    			return 0;
    
    		if (signature_len > 236) {
    			if (memcmp(&img_ofs_0x100[236], sha1_of_contents, signature_len - 236)) // 256-236 = 20
    				return 0;
    
    			// Signature passed
    			return 1;
    		}
    	}
    	return 0;
    }


    Here's the subcheck function, it looks like arbitrary-precision math, possibly mulmod

    Code:
    void __fastcall signature_subcheck(sig_ctx_t *sig_data, int *output, int *input1, int *input2)
    {
      int v5; // [email protected]
      int count; // [email protected]
      unsigned __int64 v7; // [email protected]
      unsigned __int64 v8; // [email protected]
      int inner_index; // [email protected]
      int block1_pos; // [email protected]
      int v11; // [email protected]
      __int64 v12; // [email protected]
      int v13; // [email protected]
      unsigned __int64 v14; // [email protected]
      int v15; // [email protected]
      int v16; // [sp+18h] [bp-48h]@6
      unsigned int v17; // [sp+1Ch] [bp-44h]@6
      int outer_index; // [sp+2Ch] [bp-34h]@5
    
      if ( sig_data->count > 0 )
      {
        v5 = 0;
        do
        {
          output[v5++] = 0;                         // this do while is just memset(output, 0, 4 * sig_data->count)
          count = sig_data->count;
        }
        while ( sig_data->count > v5 );
        if ( count > 0 )
        {
          outer_index = 0;
          do
          {
            v16 = input1[outer_index];
            v7 = (unsigned int)v16 * (unsigned __int64)(unsigned int)*input2 + (unsigned int)*output;// v7 = input1[outer_index] * (uint64)input2[0] + output[0]
            v17 = sig_data->seed[0] * v7;
            v8 = sig_data->seed[1] * (unsigned __int64)v17 + (unsigned int)v7;
            if ( count <= 1 )
            {
              block1_pos = 1;
            }
            else
            {
              inner_index = 0;
              block1_pos = 1;
              do
              {
                v7 = (unsigned int)v16 * (unsigned __int64)(unsigned int)input2[block1_pos]
                   + (unsigned int)output[block1_pos]
                   + HIDWORD(v7);
                v8 = sig_data->seed[inner_index + 2] * (unsigned __int64)v17 + HIDWORD(v8) + (unsigned int)v7;
                ++block1_pos;
                output[inner_index] = v8;
                ++inner_index;
              }
              while ( block1_pos < sig_data->count );
            }
            output[block1_pos - 1] = HIDWORD(v8) + HIDWORD(v7);
            if ( (HIDWORD(v8) + (unsigned __int64)HIDWORD(v7)) >> 32 )
            {
              if ( sig_data->count <= 0 )
                return;
              v11 = 0;
              v12 = 0LL;
              v13 = 0;
              do
              {
                v14 = (unsigned int)output[v11] - (unsigned __int64)sig_data->seed[v11 + 1];
                v15 = output[v11] - sig_data->seed[v11 + 1];
                output[v11] = output[v11] - sig_data->seed[v11 + 1] + v12;
                count = sig_data->count;
                ++v13;
                ++v11;
                v12 = (signed int)((__PAIR__(HIDWORD(v14), v15) + v12) >> 32);
              }
              while ( v13 < sig_data->count );
            }
            else
            {
              count = sig_data->count;
            }
            ++outer_index;
          }
          while ( outer_index < count );
        }
      }
    }


    The goal is to make it so that after all the calculations the 256 byte block located at img_sig_data+0x100 has the contents 0x00, 0x01, 0xFF * 236, and then the sha1 of our boot.img

    I'm in the middle of moving at the moment, so I don't have as much time as I would like to look at this right now, but that should clear up in a few days.

    Also, if there's any interest I can post a guide on how to get the bootloader files loaded into IDA for analysis. Some knowledge of ARM assembly would be required though.

    EDIT:

    In other news, I found what keeps resetting the 16 byte encrypted romtype in param.img. It's libcordon.so, which is from /system/app/SysScope.apk (it'll also be copied to /system/lib/libcordon.so). It's using quite a few checks to see if you've modified your system.

    There's an adb scanner, checking to see if you've changed the ro.secure or ro.debuggable props.

    The root process scanner checks running processes and returns true if any are found running as root that are not one of:
    "debuggerd", "init", "installd", "servicemanager", "vold", "zygote", "netd", "ueventd", "dock_kbd_attach", "pppd", "pppd_runner", "mpdecision", "thermald", "hdmid", "sec_keyboard", "seccmmond", "mfsc", "mfdp"

    There's also a partition check, kernel checker, su scanner, and a file scanning mechanism using data from a sqlite db

    So to completely remove the Samsung custom screen on bootup and 5 second delay you'd need to disable the SysScope.apk, then encrypt and write the 16 bytes yourself using 0xFF000000 as the first int to mark yourself as official
    70
    A gentleman named Lee contacted me via email. He said he has 0 posts so he could not post in here. This post contains his email to me. I am not wrapping it in quotes because quotes are destroyed in future posts. This is literally the best development we've had in this thread.



    ------email from Lee------
    I've been looking at the bootloader in aboot.img the past day or so and wanted to contribute what I know about the param.img partition and how it's used. I've been following the thread at xda, but since my account has 0 posts I can't actually post this in that thread.

    Please note these are a little rough around the edges, just things I jotted down while reverse engineering.

    param.img Structure

    At offset 0 there's an 88 byte structure I've called the header

    struct param_header {
    int status; // need to investigate more. some relationships between this and boot modes. 4 == firmware error int unk_04; // haven't seen this used anywhere int unk_08; // haven't seen this used anywhere int emmc_checksum_attempted; int emmc_checksum_ok; int nvdata_backup; // says whether we have a backup of modemst1 in "fsg" partition and a backup of modemst2 in "backup" partition?
    int unk_18[16]; // haven't seen this used anywhere };

    status (NEEDS WORK):
    1 = ?
    2 = boot_mode 3?
    3 = recovery?
    4 = boot_mode 1 - fastboot. displays "firmware update issue" image
    5 = boot_mode 4?


    at offset 0x900000 there's a structure controlling some debug variables

    struct param_debug {
    int debug_level;
    int unk_04; // 4 in dumps. haven't seen this used anywhere int unk_08; // 0 in dumps. haven't seen this used anywhere int emmc_checksum_attempted; // mirror of param_header.emmc_checksum_attempted
    int emmc_checksum_ok; // mirror of param_header.emmc_checksum_ok };

    About param_debug.debug_level:
    It has 3 possible values, and it changes some flags are passed to the kernel.
    DLOW is the default, but some features like ramdump mode only work on DMID or DHIG

    1. 0x574F4C44 (DLOW) - Low debug setting strcat(boot_img_hdr->cmdline, " androidboot.debug_level=0x4f4c");// OL strcat(boot_img_hdr->cmdline, " sec_debug.enable=0"); strcat(boot_img_hdr->cmdline, " sec_debug.enable_user=0");

    2. 0x44494D44 (DMID) - Mid-level debugging strcat(boot_img_hdr->cmdline, " androidboot.debug_level=0x494d");// IM strcat(boot_img_hdr->cmdline, " sec_debug.enable=1"); strcat(boot_img_hdr->cmdline, " sec_debug.enable_user=0");

    3. 0x47494844 (DHIG) - Full debugging
    strcat(boot_img_hdr->cmdline, " androidboot.debug_level=0x4948");// IH strcat(boot_img_hdr->cmdline, " sec_debug.enable=1"); strcat(boot_img_hdr->cmdline, " sec_debug.enable_user=1"); strcat(boot_img_hdr->cmdline, " slub_debug=FPUZ");

    Check drivers/misc/sec_misc.c for what these values do for the kernel


    At offset 0x9FFC00 (sizeof(param.img) - 0x400 is how the offset is calculated by the BL):
    Here are 16 bytes unique to each device, and they are part of what determines whether or not you have a custom rom.

    It's AES128 encrypted using a key made from the emmc's psn and some static data

    Key generation:
    First, the 4byte psn is expanded to 8 bytes

    char first_half[14];
    snprintf(first_half, 13, "%08x", mmc_get_psn()); memcpy(aes_initial_key, first_half, 8);

    The second half is calculated based on all static data

    char custom_check_index_shuf_table[] = { 1, 3, 2, 4, 5, 1, 0, 4, 4, 5, 4, 0 }; char custom_check_table[] = { 0x40, 0x74, 0x25, 0x61, 0x21, 0x74, 0x70, 0x62, 0x62, 0x24, 0x33, 0x5E }; char romtype_enc_key_buf[32];

    char* custom_check_shuffle_calc(signed int always_199, int count) { int out_index; // [email protected] int last_index; // [email protected] int odd_index; // [email protected] int table_index; // [email protected] char table_value;

    if ( count <= 0 )
    {
    out_index = 0;
    }
    else
    {
    out_index = 0;
    last_index = 0;
    do
    {
    odd_index = always_199 & 1;
    always_199 >>= 1;
    table_index = odd_index + 2 * last_index; table_value = custom_check_table[table_index]; last_index = custom_check_index_shuf_table[table_index];
    romtype_enc_key_buf[out_index++] = table_value; } while ( out_index != count ); } romtype_enc_key_buf[out_index] = 0; return romtype_enc_key_buf; }

    This function is used like this (the parameters are always 199 and 8 in the vzw aboot):
    char* second_half = custom_check_shuffle_calc(199, 8); memcpy(&aes_initial_key[8], second_half, 8);

    Now we have 16 bytes in aes_initial_key, but it's shuffled again with the following function

    char custom_check_final_index_table[] = { 0, 4, 5, 0xD, 3, 8, 0xE, 9, 0xA, 2, 1, 7, 0xB, 6, 0xC, 0xF }; void custom_check_shuffle_final_key(char *iv, char *final) { int v2; // [email protected] int v5; // [email protected]

    v2 = 0;
    do
    {
    final[custom_check_final_index_table[v2]] = iv[v2];
    v2++;
    }
    while ( v2 != 16 );
    v5 = 0;
    do
    {
    final[custom_check_final_index_table[v5]] = iv[v5] ^ final[v5];
    v5++;
    }
    while ( v5 != 16 );
    }

    char aes_final_key[16];
    custom_check_shuffle_final_key(aes_initial_key, aes_final_key);

    This final key should be able to decrypt the 16 bytes

    The first 4 decrypted bytes cast to an int will be 0xFF000000 if you're running an official rom, or 0xEE000000 if you've flashed something custom If it's 0xEE000000 then you will be shown the "Custom" boot screen with the padlock on it, and it also causes a call to mdelay(5000) before actually booting the kernel.
    I've also seen 0xCC000000 mentioned in debug prints, causing it to print the device status as "Scanning" instead of "Official" or "Custom"


    Unfortunately this doesn't seem to help much with the boot.img check, but I've found where that is and am reversing it now.


    ----------------------------------------------------------------------------------------------------------------------------------------------------------------

    DDI Data
    Here's where the values like the flash count are stored (sometimes this might be called triangle state?) It's stored at 0x3FFE00 on the mmc

    struct ddi_data {
    int magic; // must be 0x12340012
    int custom_flash_count;
    int odin_count;
    int binary_type; // 0 = samsung official, 1 = custom, 2 = "Unknown"
    char model_name[16];
    int rom_type; // this is the first 4 bytes of the decrypted 16 bytes in the param partition. 0xFF000000 = samsung, 0xEE000000 = custom }


    ----------------------------------------------------------------------------------------------------------------------------------------------------------------

    Reboot Reason

    Values and effects for the reboot reason stored at 0x2A03F65C

    0x12345671 - ?
    0x12345678 - Normal mode


    0x77665500 - FASTBOOT_MODE. displays "downloading" boot image
    0x77665501 - ? seen checked but haven't found it used anywhere
    0x77665502 - RECOVERY_MODE. sets param_header.state to 3
    0x77665503 - sets param_header.state to 4. haven't seen it actually used

    0x77665507 - display the "not authorized" picture

    if ((reason & ~0xF) == 0x77665510) then they're commands for manipulating the nvdata I wouldn't play around with these unless you really know what you're doing All of them reboot the device into the normal mode except 0x77665515

    0x77665511 - copy modemst1 to fsg partition and copy modemst2 to backup partition. sets param_header.nvdata_backup to 1
    0x77665512 - copy fsg to modemst1 and copy backup to modemst2. checks to ensure param_header.nvdata_backup=1 first
    0x77665514 - erase fsg and backup partitions. clears param_header.nvdata_backup
    0x77665515 - same as 0x77665511 but then reboots the device into RECOVERY_MODE


    0x776655EE - RAMDUMP_MODE (only valid if param_debug.debug_level is DMID/DHIG)


    0xABCD4F4C - set param_debug.debug_level to DLOW 0xABCD494D - set param_debug.debug_level to DMID
    0xABCD4948 - set param_debug.debug_level to DHIG

    ----------------------------------------------------------------------------------------------------------------------------------------------------------------

    boot_type INCOMPLETE
    1 = fastboot
    2 = ramdump mode
    3 = recovery. resets param_debug
    4 = ?


    ----------------------------------------------------------------------------------------------------------------------------------------------------------------

    USB Flags INCOMPLETE

    0xF00 - jig mask
    0x100 - put the device into factory mode
    0x400 - change "console" boot parameter to "console=ttyHSL0,115200,n8%s" where %s is replaced by whatever was originally after "console="

    ----------------------------------------------------------------------------------------------------------------------------------------------------------------

    ODIN

    In addition to the ODIN/LOKE handshake sequence I saw in heimdall, there are 2 more in the S3.
    Send "FPGM" and you should get a response of "OK". It functions exactly as the ODIN/LOKE sequence.
    Send "ROOTING" and it responds with the current DDI data and terminates.

    -Lee