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[Verizon] Stock Images & MD5/SHA1 verification?

Discussion in 'Android Devices' started by edhgreatone, Dec 26, 2011.

  1. edhgreatone

    edhgreatone Well-Known Member
    Thread Starter

    Got a few questions as I've been out of the root game for quite some time...

    Getting a little confused with the stock images terminology and the point of the verification process...

    Is the term stock image and a rom backup on the original non flashed ICS the same thing? How does an image differ from a rom?

    I clicked the verification md5 link but having trouble following, does anybody have a step by step and what's the point of this --- does it prevent non compatibility issues?

    I have astro manager and know how to get to the check sum but what exactly am I verifying?
     



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  2. SolidOrange

    SolidOrange Android Expert

    verifying an MD5 sum makes sure that the file in question downloaded correctly and in its entirety. losing your connection during the download or a corrupt version of the file will generate a different MD5 than that of the original upload. trying to load a corrupt ROM file could cause some very serious issues, so it is always best to make sure they match.

    hope that clears it up for you! :cool:
     
    edhgreatone likes this.
  3. edhgreatone

    edhgreatone Well-Known Member
    Thread Starter

    Hey thanks solid orange ... that makes sense, everybody is so helpful on this forum compared to others ...

    So can somebody explain how I validate the string of characters in the check sum? How do I know what is reflecting in the downloaded .zip file is what I expect? Also why would I need astro file manager if I download rom to my PC first? Is this only for those who download roms directly to phone prior to flashing?

    I wish I knew to do this in my first from flash ... it only downloaded partially and kept failing in boot loader and I couldn't figure out why
     
    SolidOrange likes this.
  4. SolidOrange

    SolidOrange Android Expert

    the md5 should be provided by the developer/uploader of any rom. to check it on your phone, open astro, navigate to the file, long press it and select "details". to check it on your computer download a checksum utility such as this, although there are many others.
     
  5. edhgreatone

    edhgreatone Well-Known Member
    Thread Starter

    I see, appreciate the explanation.
     
  6. scary alien

    scary alien not really so scary
    VIP Member

    Guys,

    Sorry I didn't see this thread earlier...it certainly is a very good idea to check validate your checksums for any file you might flash, either with fastboot or via ClockworkMod custom recovery.

    ClockworkMod does not, by default, verify the signatures or that a file has a signature prior to flashing. You can use the "toggle signature verification" in CWM, but, in my opinion, signature verification should be ON by default and not OFF.

    Not having previously verified either a checksum (such as an MD5 or SHA1) or performing signature verification means that you could end-up flashing a partial or corrupted file (that can't be good, right ;)).

    I had a set of stock GNex image files on my PC last weekend that turned-out were partial downloads...that was the weekend I spent flashing back to stock about 8 times. Thankfully, I double-checked the MD5s before trying to flash them.

    There is one other option you have for files that are signed (this means that there is checksum information built-in to the .zip archive itself that can be verified without you explicitly comparing them). Application .apk files are signed, so are (usually) custom ROM .zip files, as well as .jar files.

    My AFV app has an option, Verify Jar-type File, that can check to see if a file is whole and uncorrupt without you having to know (and compare) the MD5 (or SHA1) checksums. It also has a function for verifying the checksums of your Nandroid backups (as well as a few others :)).

    Please let me know if you have any other questions.

    Cheers!
     

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The Galaxy Nexus release date was November 2011. Features and Specs include a 4.65" inch screen, 5MP camera, 1GB RAM, TI OMAP 4460 processor, and 1750mAh battery.

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