sunnymoon Posted May 15, 2016 Posted May 15, 2016 (edited) Hi - to avoid a long long post - i'll keep it to the point. Wording chosen carefully - to create focus. Journey - stages of relevance: Start: Simply find downloadable Iso/Image file - (hash (SHA1/MD5) listed) - on (any) authors website. End: Burned DVD (of that image) in my hand. In between these stages, much can happen. I am asking, if there is a technically pure/competent/accurate way, of directly testing/establishing/checking- that the burnt DVD is precisely & exactly the same, as the image that was on the authors server (i.e before I downloaded it) - e.g Antivirus Rescue Boot disc. Why: Contamination can happen, the moment the image is downloaded to my hard disk, and a sophisticated rootkit could intercept and commender any hash/verification process. But - I want to keep the discussion of 'how' the data could get contaminated completely out of this discussion. That - is completely irrelevant to the topic I am hoping to open up. The discussion I am hoping to explore is one of verifying data transmission from the original source, to the final burned physical DVD. Please assume I have access to multiple machines, on air-locked networks. SM. Edited May 15, 2016 by sunnymoon
LIGHTNING UK! Posted May 15, 2016 Posted May 15, 2016 What's wrong with burning it in one machine, reading it back in another and md5'ing that image? Oh and this sounds like a very generic question and nothing to do with ImgBurn. You could ask it in 'chat' or any optical media related forum.
sunnymoon Posted May 15, 2016 Author Posted May 15, 2016 LIGHTNING UK!, Thank you for responding. I needed to know if such a thing was possible, before I asked how. I posted here - because I want to see if imgburn covers this. Can I ask if there is a guide - showing the vectors imgburn offers - in achieving my intended goal. For example - is it only MD5 - or are there other methods too? etc. I'm hoping that I can learn something about this topic - not just request an easy short-cut to a solution. SM P.s Please move the thread to another forum if more appropriate. I hope to explore the extent and type of verification imgburn can do - whether it uses sampling or comprehensive bit for bit analysis - I would like to open the topic up for exploring so other forum members can learn something too.
LIGHTNING UK! Posted May 15, 2016 Posted May 15, 2016 ImgBurn reads each sector from the image and disc, comparing the two at byte level. You could use the program's internal md5 stuff or use something like hashtab to calculate md5 / sha1 on the image once ImgBurn has created it. There's no guide for verifying, no. Just go into write mode, load your image, load your disc and click the start button.
sunnymoon Posted May 15, 2016 Author Posted May 15, 2016 (edited) Thank you for being patient with me. I am a noob - and I'm trying to learn. I think I haven't done a good job of communicating my thought process - so I'm going to give it another go: User is helping repair a family members PC - as its performing poorly. Repairman suspects it's infected with light malware. Repairman proceeds to download (any) antivirus rescue disc iso image to the hardrive (e.g Kaspersky rescue disc). Unbeknownst to the repairman, it's not a light/minor infection - but a rootkit. The rootkit infects the image file as soon as the download is complete. Repairman proceeds to burn this image to dvd using imgburn, (wrongly thinking all is okay). Imgburn burns then verification proceeds. What would be the result of the verification? So my technical question is - How could the disc be checked (using imgburn) - not against this locally stored image file, but against the image checksum, as originally advertised on the kaspersky website. [Yes - ideally - download burn images on a clean machine, but many who imagine their machine is clean - are unknowingly wrong]. Up to this point, I've been using imgbrn quite simply. Now I want to become a power user. Most Sincerely - thank you for your patience and help. SM Edited May 15, 2016 by sunnymoon
LIGHTNING UK! Posted May 16, 2016 Posted May 16, 2016 If you enable the MD5 option within the settings, the program will log the MD5 of the disc once it's burnt and/or read/verified it. You can compare that value to what's on the website. Failing that, do what I said before and burn the disc, then read it back to a new image. Run any md5 / sha1 tool against that new image and see how the results compare to what's on the website.
sunnymoon Posted May 16, 2016 Author Posted May 16, 2016 Appreciate the response LIGHTNING UK!, This is the reason I have some confusion. emap is trying to achieve the same goal as me i.e. a way to forensically check how a burned physical disc - compares to the original virgin image checksum. But, there seems to be an issue about extra sectors being written to the disc - and the whole thing fails:: http://forum.imgburn.com/index.php?/topic/6483-verifying-burned-dvds-by-md5-instead-of-iso/ The reason I'm confused - emap did as suggested in the posts - m5 check, yet all attempts failed. [tl:dr - emap has DVD's burned long ago - did not want to store terabytes of image/iso files for years - emap just kept their checksums in a document instead. Emap asks if there is a way to compare the DVD's against the checksums to check data integrity/disc viability - as some discs became scratched over time - and in addition emap realises the likelihood of degradation, of the disc material over time. The thread is very interesting - and enlightening]. As you can tell - I'm just trying to explore how to do this technically right, so I will be genuinely competent. Would appreciate your insights and guidance from here. Again - my thanks and respects for exploring this topic so we can all learn. SM.
LIGHTNING UK! Posted May 16, 2016 Posted May 16, 2016 Drives do sometimes round up the number of sectors being burnt to the end of the ecc block. That's to say, the number burnt is then a multiple of 16 (or 32 for BD). So the best thing to do in these situations is build the image whereby its size is a multiple of 16. ImgBurn always builds its images in this way. That way, when you burn it, no 'padding' gets added by the drive and the image can be read back perfectly to the size it started off at - md5 etc matching perfectly. Burning to DVD+R usually always results in the burnt size being a multiple of 16. For DVD-R, its basically down to the individual drive and probably even firmware revisions of said drive. They never used to round up, but these days there are less options for optical hardware and more probably do.
sunnymoon Posted May 16, 2016 Author Posted May 16, 2016 Thanks for the reply LIGHTNING UK!, Can you point me to a guide, that can show me what settings need to be modified - so I can get under way. For e.g - in the shared thread - someone directs emap to changing to read mode (please explain why) etc. I think you know the level of accuracy at which I'm trying to operate - as close to forensic as possible. If there is no guide - could we please go through how to configure imgburn for this here?
LIGHTNING UK! Posted May 16, 2016 Posted May 16, 2016 I've only mentioned the md5 setting. That's in the settings on the 'general' tab... Page 2. 'Calculate MD5 Hash Values'. Read mode issues a few different commands to write mode when initialising the disc - as obviously it's meant for discs with data on them rather than blank ones. Those commands provide mode info about the disc and it all gets written in the disc info box on the right of the main window.
sunnymoon Posted May 16, 2016 Author Posted May 16, 2016 I've only mentioned the md5 setting. That's in the settings on the 'general' tab... Page 2. 'Calculate MD5 Hash Values'. Read mode issues a few different commands to write mode when initialising the disc - as obviously it's meant for discs with data on them rather than blank ones. Those commands provide mode info about the disc and it all gets written in the disc info box on the right of the main window. Okay so MD5 tick box checked. Re read mode - it's not clear - use or don't use?
LIGHTNING UK! Posted May 16, 2016 Posted May 16, 2016 If you want to create an image file by reading the disc, yes.
sunnymoon Posted May 16, 2016 Author Posted May 16, 2016 Ok. I'm going to do a few test burns and verifications - using MD5. I'm asking what settings I should change - (all of them) - so that A) I can do ask we have discussed and So that any log files you might need/ask for are configured properly - and include all the details you 'might' need/want.
LIGHTNING UK! Posted May 16, 2016 Posted May 16, 2016 There's nothing really special about what you're trying to do. The default options work fine. Just enable the md5 one so that one extra bit of info gets logged. If you want to query anything within the log or about what's happened, just post the full log of the burn + verify session and then post the disc info of the burnt disc when taken from Read mode.
sunnymoon Posted May 17, 2016 Author Posted May 17, 2016 (edited) Program installed. No settings changed - except MD5 setting, (General>pane 2 - both boxes checked). Test image - Kaspersky Rescue CD. Medium used - DVD Before proceeding - please tell me if A, B & C were what you asked for - or if I am missing anything. A).Straight run "Burn image + verify": I 00:29:03 ImgBurn Version 2.5.8.0 started! I 00:29:04 Microsoft Windows 8 Professional Edition (6.2, Build 9200) I 00:29:04 Total Physical Memory: 3,135,604 KiB - Available: 2,247,672 KiB I 00:29:04 Initialising SPTI... I 00:29:04 Searching for SCSI / ATAPI devices... I 00:29:04 -> Drive 1 - Info: Slimtype DVDRW SSM-8515S GRS6 (D:) (ATA) I 00:29:04 Found 1 DVD±RW/RAM! I 00:30:44 Operation Started! I 00:30:44 Source File: C:\Users\Jay\Desktop\Kav Boot Disc\kav_rescue_10.iso I 00:30:44 Source File Sectors: 140,611 (MODE1/2048) I 00:30:44 Source File Size: 287,971,328 bytes I 00:30:44 Source File Volume Identifier: KRD10 I 00:30:44 Source File File System(s): ISO9660 (Bootable), Joliet I 00:30:44 Destination Device: [1:0:0] Slimtype DVDRW SSM-8515S GRS6 (D:) (ATA) I 00:30:44 Destination Media Type: DVD+R (Disc ID: MCC-004-00) I 00:30:44 Destination Media Supported Write Speeds: 2.4x, 4x, 6x, 8x I 00:30:44 Destination Media Sectors: 2,295,104 I 00:30:44 Write Mode: DVD I 00:30:44 Write Type: DAO I 00:30:44 Write Speed: 8x I 00:30:44 DVD+R Reserve Track: No I 00:30:44 Link Size: Auto I 00:30:44 Lock Volume: Yes I 00:30:44 Test Mode: No I 00:30:44 OPC: No I 00:30:44 BURN-Proof: Enabled I 00:30:44 Write Speed Successfully Set! - Effective: 11,080 KB/s (8x) I 00:30:44 Book Type Setting: N/A (Reason: Invalid Field in CDB) I 00:30:44 Advanced Settings - Force HT: N/A, Online HT: N/A, OverSpeed: N/A, SmartBurn: Yes I 00:30:45 Filling Buffer... (80 MiB) I 00:30:45 Writing LeadIn... I 00:32:23 Writing Session 1 of 1... (1 Track, LBA: 0 - 140610) I 00:32:23 Writing Track 1 of 1... (MODE1/2048, LBA: 0 - 140610) I 00:33:37 Synchronising Cache... I 00:33:38 Closing Track... I 00:33:42 Finalising Disc... I 00:34:54 Image MD5: df17c92ee35ebbbe17760266f9acb35c I 00:34:54 Exporting Graph Data... I 00:34:54 Graph Data File: C:\Users\Jay\AppData\Roaming\ImgBurn\Graph Data Files\Slimtype_DVDRW_SSM-8515S_GRS6_17-MAY-2016_00-30_MCC-004-00_8x.ibg I 00:34:54 Export Successfully Completed! I 00:34:54 Operation Successfully Completed! - Duration: 00:04:10 I 00:34:54 Average Write Rate: 3,800 KiB/s (2.8x) - Maximum Write Rate: 5,309 KiB/s (3.9x) I 00:34:54 Cycling Tray before Verify... I 00:35:33 Device Ready! I 00:35:39 Operation Started! I 00:35:39 Source Device: [1:0:0] Slimtype DVDRW SSM-8515S GRS6 (D:) (ATA) I 00:35:39 Source Media Type: DVD+R (Book Type: DVD+R) (Disc ID: MCC-004-00) I 00:35:39 Source Media Supported Read Speeds: 2x, 3.5x, 4x, 6x, 8x I 00:35:39 Source Media Supported Write Speeds: 2.4x, 4x, 6x, 8x I 00:35:39 Source Media Sectors: 140,624 (Track Path: PTP) I 00:35:39 Source Media Size: 287,997,952 bytes I 00:35:39 Image File: C:\Users\Jay\Desktop\Kav Boot Disc\kav_rescue_10.iso I 00:35:39 Image File Sectors: 140,611 (MODE1/2048) I 00:35:39 Image File Size: 287,971,328 bytes I 00:35:39 Image File Volume Identifier: KRD10 I 00:35:39 Image File File System(s): ISO9660 (Bootable), Joliet I 00:35:39 Read Speed (Data/Audio): MAX / MAX I 00:35:40 Read Speed - Effective: 3.2x - 3.5x I 00:35:40 Verifying Session 1 of 1... (1 Track, LBA: 0 - 140610) I 00:35:40 Verifying Track 1 of 1... (MODE1/2048, LBA: 0 - 140610) I 00:36:37 Device MD5: df17c92ee35ebbbe17760266f9acb35c I 00:36:37 Device (Padded) MD5: f65d18117fcd69991b4f24a18451491f I 00:36:37 Image MD5: df17c92ee35ebbbe17760266f9acb35c I 00:36:38 Exporting Graph Data... I 00:36:38 Graph Data File: C:\Users\Jay\AppData\Roaming\ImgBurn\Graph Data Files\Slimtype_DVDRW_SSM-8515S_GRS6_17-MAY-2016_00-30_MCC-004-00_8x.ibg I 00:36:38 Export Successfully Completed! I 00:36:38 Operation Successfully Completed! - Duration: 00:00:58 I 00:36:38 Average Verify Rate: 4,933 KiB/s (3.6x) - Maximum Verify Rate: 5,279 KiB/s (3.9x) --- Slimtype DVDRW SSM-8515S GRS6 (ATA) Current Profile: DVD+R Disc Information: Status: Complete State of Last Session: Complete Erasable: No Sessions: 1 Sectors: 140,624 Size: 287,997,952 bytes Time: 31:16:74 (MM:SS:FF) MID: MCC-004-00 Supported Write Speeds: 2.4x, 4x, 6x, 8x TOC Information: Session 1... (LBA: 0) -> Track 01 (Mode 1, LBA: 0 - 140623) -> LeadOut (LBA: 140624) Disc Control Blocks Information: SONY DW-G520AGRS6 Physical Format Information (ADIP): Disc ID: MCC-004-00 Book Type: DVD+R Part Version: 1 Disc Size: 120 mm Maximum Read Rate: Not Specified Number of Layers: 1 Track Path: Parallel Track Path (PTP) Linear Density: 0.267 um/bit Track Density: 0.74 um/track First Physical Sector of Data Area: 196,608 Last Physical Sector of Data Area: 2,491,711 Last Physical Sector in Layer 0: 0 Physical Format Information (Last Recorded): Disc ID: MCC-004-00 Book Type: DVD+R Part Version: 1 Disc Size: 120 mm Maximum Read Rate: Not Specified Number of Layers: 1 Track Path: Parallel Track Path (PTP) Linear Density: 0.267 um/bit Track Density: 0.74 um/track First Physical Sector of Data Area: 196,608 Last Physical Sector of Data Area: 337,231 Last Physical Sector in Layer 0: 0 Performance (Write Speed): Descriptor 1... -> B0: 0x00, B1: 0x00, B2: 0x00, B3: 0x00 -> EL: 140623 (0x0002254F) -> RS: 11,080 KB/s (8x) - WS: 3,324 KB/s (2.4x) Descriptor 2... -> B0: 0x00, B1: 0x00, B2: 0x00, B3: 0x00 -> EL: 140623 (0x0002254F) -> RS: 11,080 KB/s (8x) - WS: 5,540 KB/s (4x) Descriptor 3... -> B0: 0x00, B1: 0x00, B2: 0x00, B3: 0x00 -> EL: 140623 (0x0002254F) -> RS: 11,080 KB/s (8x) - WS: 8,310 KB/s (6x) Descriptor 4... -> B0: 0x00, B1: 0x00, B2: 0x00, B3: 0x00 -> EL: 140623 (0x0002254F) -> RS: 11,080 KB/s (8x) - WS: 11,080 KB/s (8x) B ) "Verify Disc" (against image box - DELIBERATELY UNCHECKED). I 00:42:04 ImgBurn Version 2.5.8.0 started! I 00:42:04 Microsoft Windows 8 Professional Edition (6.2, Build 9200) I 00:42:04 Total Physical Memory: 3,135,604 KiB - Available: 2,143,920 KiB I 00:42:04 Initialising SPTI... I 00:42:04 Searching for SCSI / ATAPI devices... I 00:42:05 -> Drive 1 - Info: Slimtype DVDRW SSM-8515S GRS6 (D:) (ATA) I 00:42:05 Found 1 DVD±RW/RAM! I 00:42:30 Operation Started! I 00:42:30 Source Device: [1:0:0] Slimtype DVDRW SSM-8515S GRS6 (D:) (ATA) I 00:42:30 Source Media Type: DVD+R (Book Type: DVD+R) (Disc ID: MCC-004-00) I 00:42:30 Source Media Supported Read Speeds: 2x, 3.5x, 4x, 6x, 8x I 00:42:30 Source Media Supported Write Speeds: 2.4x, 4x, 6x, 8x I 00:42:30 Source Media Sectors: 140,624 (Track Path: PTP) I 00:42:30 Source Media Size: 287,997,952 bytes I 00:42:30 Verify Against Image File: No I 00:42:30 Read Speed (Data/Audio): MAX / MAX I 00:42:31 Read Speed - Effective: 3.2x - 3.5x I 00:42:31 Verifying Session 1 of 1... (1 Track, LBA: 0 - 140623) I 00:42:31 Verifying Track 1 of 1... (MODE1/2048, LBA: 0 - 140623) I 00:43:34 Device MD5: f65d18117fcd69991b4f24a18451491f I 00:43:35 Exporting Graph Data... I 00:43:35 Graph Data File: C:\Users\Jay\AppData\Roaming\ImgBurn\Graph Data Files\Slimtype_DVDRW_SSM-8515S_GRS6_17-MAY-2016_00-42_MCC-004-00.ibg I 00:43:35 Export Successfully Completed! I 00:43:35 Operation Successfully Completed! - Duration: 00:01:04 I 00:43:35 Average Verify Rate: 4,536 KiB/s (3.4x) - Maximum Verify Rate: 5,279 KiB/s (3.9x) ---- Slimtype DVDRW SSM-8515S GRS6 (ATA) Current Profile: DVD+R Disc Information: Status: Complete State of Last Session: Complete Erasable: No Sessions: 1 Sectors: 140,624 Size: 287,997,952 bytes Time: 31:16:74 (MM:SS:FF) MID: MCC-004-00 Supported Read Speeds: 2x, 3.5x, 4x, 6x, 8x Current Read Speed: 3.2x - 3.5x TOC Information: Session 1... (LBA: 0) -> Track 01 (Mode 1, LBA: 0 - 140623) -> LeadOut (LBA: 140624) Track Information: Session 1... -> Track 01 (LTSA: 0, LTS: 140624, LRA: 0) Disc Control Blocks Information: SONY DW-G520AGRS6 Physical Format Information (ADIP): Disc ID: MCC-004-00 Book Type: DVD+R Part Version: 1 Disc Size: 120 mm Maximum Read Rate: Not Specified Number of Layers: 1 Track Path: Parallel Track Path (PTP) Linear Density: 0.267 um/bit Track Density: 0.74 um/track First Physical Sector of Data Area: 196,608 Last Physical Sector of Data Area: 2,491,711 Last Physical Sector in Layer 0: 0 Physical Format Information (Last Recorded): Disc ID: MCC-004-00 Book Type: DVD+R Part Version: 1 Disc Size: 120 mm Maximum Read Rate: Not Specified Number of Layers: 1 Track Path: Parallel Track Path (PTP) Linear Density: 0.267 um/bit Track Density: 0.74 um/track First Physical Sector of Data Area: 196,608 Last Physical Sector of Data Area: 337,231 Last Physical Sector in Layer 0: 0 C) "Create Image from Disc" I 00:45:10 ImgBurn Version 2.5.8.0 started! I 00:45:10 Microsoft Windows 8 Professional Edition (6.2, Build 9200) I 00:45:10 Total Physical Memory: 3,135,604 KiB - Available: 2,192,952 KiB I 00:45:10 Initialising SPTI... I 00:45:10 Searching for SCSI / ATAPI devices... I 00:45:11 -> Drive 1 - Info: Slimtype DVDRW SSM-8515S GRS6 (D:) (ATA) I 00:45:11 Found 1 DVD±RW/RAM! I 00:46:24 Operation Started! I 00:46:24 Source Device: [1:0:0] Slimtype DVDRW SSM-8515S GRS6 (D:) (ATA) I 00:46:24 Source Media Type: DVD+R (Book Type: DVD+R) (Disc ID: MCC-004-00) I 00:46:24 Source Media Supported Read Speeds: 2x, 3.5x, 4x, 6x, 8x I 00:46:24 Source Media Supported Write Speeds: 2.4x, 4x, 6x, 8x I 00:46:24 Source Media Sectors: 140,624 (Track Path: PTP) I 00:46:24 Source Media Size: 287,997,952 bytes I 00:46:24 Source Media Volume Identifier: KRD10 I 00:46:24 Source Media File System(s): ISO9660 (Bootable), Joliet I 00:46:24 Read Speed (Data/Audio): MAX / 8x I 00:46:24 Destination File: C:\Users\Jay\Desktop\Kav Boot Disc\RIPBACK.ISO I 00:46:24 Destination Free Space: 361,225,924,608 Bytes (352,759,692.00 KiB) (344,491.89 MiB) (336.42 GiB) I 00:46:24 Destination File System: NTFS I 00:46:24 File Splitting: Auto I 00:46:25 Read Speed - Effective: 3.2x - 3.5x I 00:46:30 Reading Session 1 of 1... (1 Track, LBA: 0 - 140623) I 00:46:30 Reading Track 1 of 1... (MODE1/2048, LBA: 0 - 140623) I 00:47:29 Image MD5: f65d18117fcd69991b4f24a18451491f I 00:47:29 Exporting Graph Data... I 00:47:29 Graph Data File: C:\Users\Jay\AppData\Roaming\ImgBurn\Graph Data Files\Slimtype_DVDRW_SSM-8515S_GRS6_17-MAY-2016_00-46_MCC-004-00.ibg I 00:47:29 Export Successfully Completed! I 00:47:29 Operation Successfully Completed! - Duration: 00:01:04 I 00:47:29 Average Read Rate: 4,394 KiB/s (3.2x) - Maximum Read Rate: 5,279 KiB/s (3.9x) ----- Slimtype DVDRW SSM-8515S GRS6 (ATA) Current Profile: DVD+R Disc Information: Status: Complete State of Last Session: Complete Erasable: No Sessions: 1 Sectors: 140,624 Size: 287,997,952 bytes Time: 31:16:74 (MM:SS:FF) MID: MCC-004-00 Supported Read Speeds: 2x, 3.5x, 4x, 6x, 8x Current Read Speed: 3.2x - 3.5x File System Information: Sectors: 140,611 Size: 287,971,328 bytes Time: 31:16:61 (MM:SS:FF) TOC Information: Session 1... (LBA: 0) -> Track 01 (Mode 1, LBA: 0 - 140623) -> LeadOut (LBA: 140624) Track Information: Session 1... -> Track 01 (LTSA: 0, LTS: 140624, LRA: 0) Disc Control Blocks Information: SONY DW-G520AGRS6 Physical Format Information (ADIP): Disc ID: MCC-004-00 Book Type: DVD+R Part Version: 1 Disc Size: 120 mm Maximum Read Rate: Not Specified Number of Layers: 1 Track Path: Parallel Track Path (PTP) Linear Density: 0.267 um/bit Track Density: 0.74 um/track First Physical Sector of Data Area: 196,608 Last Physical Sector of Data Area: 2,491,711 Last Physical Sector in Layer 0: 0 Physical Format Information (Last Recorded): Disc ID: MCC-004-00 Book Type: DVD+R Part Version: 1 Disc Size: 120 mm Maximum Read Rate: Not Specified Number of Layers: 1 Track Path: Parallel Track Path (PTP) Linear Density: 0.267 um/bit Track Density: 0.74 um/track First Physical Sector of Data Area: 196,608 Last Physical Sector of Data Area: 337,231 Last Physical Sector in Layer 0: 0 Edited May 17, 2016 by sunnymoon
sunnymoon Posted May 17, 2016 Author Posted May 17, 2016 Okay - so everything's there? There is a difference between the MD5 of the image and any verification steps the drive is doing. What Am I doing wrong? What do I need to do from here to get things working so I can compared the MD5 directly against the original of the image?
LIGHTNING UK! Posted May 17, 2016 Posted May 17, 2016 I 00:33:42 Finalising Disc... I 00:34:54 Image MD5: df17c92ee35ebbbe17760266f9acb35c I 00:34:54 Exporting Graph Data... I 00:35:40 Verifying Track 1 of 1... (MODE1/2048, LBA: 0 - 140610) I 00:36:37 Device MD5: df17c92ee35ebbbe17760266f9acb35c I 00:36:37 Device (Padded) MD5: f65d18117fcd69991b4f24a18451491f I 00:36:37 Image MD5: df17c92ee35ebbbe17760266f9acb35c I 00:36:38 Exporting Graph Data... It looks ok to me. As per one of my previous replies, drives will round up what they burn to the nearest ECC block, especially when burning DVD+R media... which is what you're using. That's why you have 2 'Device' MD5 values. One 'padded' and one that isn't. The one that isn't padded matches the image md5 and should hopefully match what's on the website you downloaded it from.
sunnymoon Posted May 17, 2016 Author Posted May 17, 2016 Thank you for your reply and continued support. Drives do sometimes round up the number of sectors being burnt to the end of the ecc block. That's to say, the number burnt is then a multiple of 16 (or 32 for BD).So the best thing to do in these situations is build the image whereby its size is a multiple of 16. ImgBurn always builds its images in this way. That way, when you burn it, no 'padding' gets added by the drive and the image can be read back perfectly to the size it started off at - md5 etc matching perfectly.Burning to DVD+R usually always results in the burnt size being a multiple of 16. For DVD-R, its basically down to the individual drive and probably even firmware revisions of said drive. They never used to round up, but these days there are less options for optical hardware and more probably do. Okay - so past the intial burn+verify run - the MD5's don't match. So If we go back to the initial question that motivated me to post this thread. If I only have an image checksum in one hand, and the physical burned disc in the other - how can I confirm the md5 / burn authenticity (on another machine) - if the image file itself has been lost? Where can I go from here to achieve my goal - what would I have to change - what options do I have? UKLIGHTNING! My sincere thanks for your patience. I am sure many others will benefit from the exploration of this topic - clearly there was quite a bit for me to learn about, and comprehend. SM.
LIGHTNING UK! Posted May 17, 2016 Posted May 17, 2016 There are no options to change. You'd have to go by the initial burn and verification process. Assuming the image/device md5 listed after the verify stage has completed matches what's on the website, make note of the padded md5 ImgBurn displays (if any). That would then become your reference md5 for checking the disc. Once you've got that reference md5 written down somewhere, you can use verify mode to generate an md5 for the disc and compare it to it. If you use media your drive doesn't 'pad', there will be no padded md5 listed and then the md5s should all match. (Image, device, website). You can then compare the website md5 against the md5 generated in verify mode.
sunnymoon Posted May 17, 2016 Author Posted May 17, 2016 There are no options to change. You'd have to go by the initial burn and verification process. Assuming the image/device md5 listed after the verify stage has completed matches what's on the website, make note of the padded md5 ImgBurn displays (if any). That would then become your reference md5 for checking the disc. Once you've got that reference md5 written down somewhere, you can use verify mode to generate an md5 for the disc and compare it to it. If you use media your drive doesn't 'pad', there will be no padded md5 listed and then the md5s should all match. (Image, device, website). You can then compare the website md5 against the md5 generated in verify mode. Ok - padding is the issue - I now understand. So - Is it my drive that is doing the padding (with any and all media), or, is it due to the media that I am using and I simple need to change it. If I want to burn iso images with no padding on my laptop drive - what should I be finding/checking/sourcing/changing?
LIGHTNING UK! Posted May 17, 2016 Posted May 17, 2016 This was covered in an earlier post. Number 8 to be exact. You'd have to try your drive to see how it behaves with DVD-R media, I don't know what it'll do.
sunnymoon Posted May 17, 2016 Author Posted May 17, 2016 (edited) Drives do sometimes round up the number of sectors being burnt to the end of the ecc block. That's to say, the number burnt is then a multiple of 16 (or 32 for BD). So the best thing to do in these situations is build the image whereby its size is a multiple of 16. ImgBurn always builds its images in this way. That way, when you burn it, no 'padding' gets added by the drive and the image can be read back perfectly to the size it started off at - md5 etc matching perfectly. Burning to DVD+R usually always results in the burnt size being a multiple of 16. For DVD-R, its basically down to the individual drive and probably even firmware revisions of said drive. They never used to round up, but these days there are less options for optical hardware and more probably do. You're right - apologies. So in summary, for those reading this in the future, using imgburn: Make sure the options Setting>General>Page 2 - check "Calculate MD5 Hash Values" & "Compare MD5 Hash Values" boxes. Burn the same iso file on different media - start with +R then -R - to check if any padding gets added to either type, by your dvd burner drive. Hopefully, with one of them, it won't. Use that type, if you want to check if the physically burned DVD (md5 hash) - matches exactly/precisely the md5 of the original iso/image file., that you downloaded, any-time in the future. Caveat: Your drive (either because of it's hardware, or the current firmware on it) might add padding, regardless of the media (type) you use. The only way to find out if you can get perfect image transmission - is to test different media - and then to check if there is padding, If it is there whichever media you use - the only option seems to be, try different firmware - if this doesn't work then: ______________________________ LIGHTNING UK! - I'll let you finish-off/ add anything to the summary. Edited May 17, 2016 by sunnymoon
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