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[GUIDE] How to check the INTERGITY of a ROM

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The "A" Factor
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(Last edited by The "A" Factor; 1st February 2014 at 04:41 PM.)
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Default [GUIDE] How to check the INTERGITY of a ROM

Hello everyone !

Many a times it happens that we get "Status 7 Error" in Recovery while trying to Flash a Rom or sometimes it may happen that Rom is working fine for everyone but when we try to install the same Rom it gets stuck at Boot or some components don't work as they should .


*What to do in such cases ???
-Well the FIRST thing to do in such situations is check the Integrity of the Rom file that you have downloaded rather than blaming the developer or spamming threads.


*What is File Integrity ???

-State of a computer (electronic) file in which no alteration, addition, or deletion has been made, and which is exactly the way it was stored by its originator.
So in simple words , the Rom file is same as the Author has uploaded it on server and is not altered i.e. corrupted while downloading .


Here I'll Explain three methods to test the integrity of the Rom that you have downloaded :
1.Using 7-Zip or WinRar (Extremely Easy).
2.Using a software to check the MD5-Check sum (Moderately Easy).
3.Using a file explorer to check the MD5-Check sum (Extremely Easy).






Using 7-Zip



1.Download :
So first of all you need to download the 7-zip compression software which is Open Source (which means FREE!!!) and is one of the Best and reliable compression Tool for Windows/Linux

[Download Link : http://www.7-zip.org/download.html ]


2.Install :
duh ...! Obviously now you have to install 7-zip :P



3.Perform Integrity check on Rom file :
Go to the location where the Rom that you desire to install is present .
Now,
Right Click on the Rom File > Select 7-zip > Select "Test Archive"








If the result dialog box shows "No Errors" then your Rom file is perfectly fine !






Using MD5 Check Sum



*What is MD5 Checksum ???
-The MD5 message-digest algorithm is a widely used cryptographic hash function producing a 128-bit (16-byte) hash value, typically expressed as a 32 digit hexadecimal number. MD5 has been utilized in a wide variety of security applications. It is also commonly used to check data integrity..

In Simple words MD5 is a mathematical algorithm which performs the calculation on the File and out comes a long hexedecimal number which is refered to as the MD5 checksum.




On PC :

1.Download & Install :
Get any software which calculates MD5 checksum .
Or you can use online tool as well .


2.Perform Integrity check on Rom file :
Select the Rom file and gets it's MD-5 Check Sum value .
for eg. you get it as D93975A6E8CDA54EB61B29A801FA82E9



3.Compare the values with original one :
Now Compare the value that you got in above step with the one given by the Rom's developer or in the Hosting Site .
If they are same then your file is not corrupted !
In the following video I'll demonstrate how to Check the File Integrity using online MD5 Calculation Tool :



On phone :

1.Download & Install :
Get any app that checks the Md5 checksum
(I'm using a file explorer here : Explorer)


2.Perform Integrity check on Rom file :
Select the Rom file and long press it > Go to properties > last option is the MD5 checksum.
for eg. you get it as D93975A6E8CDA54EB61B29A801FA82E9


3.Compare the values with original one :
Now Compare the value that you got in above step with the one given by the Rom's developer or in the Hosting Site .
If they are same then your file is not corrupted !





NOTE:
*If your checksum matches the one posted by the dev, you can be sure you have an accurate copy of the downloaded file. If they don't match, then your download is either corrupt, or possibly some kind of trojan.

*You should never install any software if the MD5 sum does not match the one provided by the dev. Instead, try downloading the file again, perhaps from a different mirror. If all else fails, contact the dev as it's possible they might have posted an incorrect checksum, or may have an alternate means by which you can obtain the file.



REMEMBER : Do this procedure twice (Any of the two methods):
1. When you download the Rom(or any file) on PC
2. After transferring the Rom(or any file) to your device .


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BajoPrimate
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Hi The "A" Factor. A very good and clear guide, to check the integrity of every downloaded and transferred file could do our life easier, avoiding lots of unnecessary problems.
Thanks a lot.
Cheers.

Sent from my LG P76020L-EUR-XX unlocked and rooted
"The cost is never discussed at the outset"
GT-S5830 on ROM-NVKY-KITKAT-RC1 (25-12-13)
L9 P76020L-EUR-XX unlocked & rooted
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