doubt about md5 hashes

[Noob Saibot]

Hi there, I am a bit confused about md5 hash value imgburn delivers. I am burning a x360 game, and when the write finishes I have a certain md5. Using the same disc in the same drive imgburn gives another hash value after "read mode". How come? Shouldn't them be the same? Here are the logs:

 

I 03:52:23 ImgBurn Version 2.4.2.0 started!

I 03:52:23 Microsoft Windows XP Professional (5.1, Build 2600 : Service Pack 3)

I 03:52:23 Total Physical Memory: 522,988 KB - Available: 294,740 KB

I 03:52:23 Initialising SPTI...

I 03:52:23 Searching for SCSI / ATAPI devices...

I 03:52:23 Found 1 DVD-ROM and 2 DVD

[LIGHTNING UK!]

E 03:52:39 Failed to check for ImgBurn update!

 

Why? Do you block it at your firewall? Either let it through or turn off the update checking. It's pointless having it enabled and then blocking it.

 

I 03:53:16 Writing Session 1 of 1... (1 Track, LBA: 0 - 3825923)

...

I 22:44:27 Reading Session 1 of 1... (1 Track, LBA: 0 - 3825935)

 

Different size, different MD5.

 

DVD+ (plus) format discs will always end up with a size that's divisible (exactly) by 16.

 

So if you burn 1 sector to a disc it'll still say the size is 16 and that's what the MD5 calculation will be done on.

[Noob Saibot]

E 03:52:39 Failed to check for ImgBurn update!

 

Why? Do you block it at your firewall? Either let it through or turn off the update checking. It's pointless having it enabled and then blocking it.

 

I 03:53:16 Writing Session 1 of 1... (1 Track, LBA: 0 - 3825923)

...

I 22:44:27 Reading Session 1 of 1... (1 Track, LBA: 0 - 3825935)

 

Different size, different MD5.

 

DVD+ (plus) format discs will always end up with a size that's divisible (exactly) by 16.

 

So if you burn 1 sector to a disc it'll still say the size is 16 and that's what the MD5 calculation will be done on.

Why so picky about the update? I don't use any firewall, my internet connection was having a temporary problem, that's all. You can see later in the writing session it didn't occur.

 

So I'll never get the same md5 using this process with x360 images?

 

I'll do a quick test later, will burn another image and use the verify option straight away. Will post the log.

Edited February 27, 2009 by Noob Saibot

[Noob Saibot]

Hi there, I finally understand it, sorry for my slowness!

 

Last time a recorded a disc and used the "verify" option, then I got:

 

I 22:23:33 Device MD5: MD5 hash value 'A'
I 22:23:33 Device (Padded) MD5: MD5 hash value 'B'
I 22:23:33 Image MD5: MD5 hash value 'A'

 

In the end, imgburn says it matches but padded, I guess it's because that need to be divisible by 16 it increases the used sectors giving a different hash.