Windows 10 CheckSum issue

I've downloaded Windows 10 Pro (UK English x64) via the Media Creation Tool (twice) and ran both ISO via CheckSum calculator and oddly enough, I got two different readouts. Is this normal?

1st Download:

MD5: 955AB0FA67F6EAAD61005660F686599F
SHA-1: 1A52846E617EE2CA05816B073549FAF7E7AF3B00

2nd Download:

MS5: 824793D0A869B5CEBD8EA49A4CAAAD44
SHA-1: 85E7F19E8D024323505DE3C25B4E54FCD51325DE

Probably a difference in the install.wim. I believe Microsoft is integrating the latest updates into these ISOs.

The media creation tool is NOT downloading ISOs, people are misunderstanding what that tool does. It downloads ESD (Electronic Software Distribution) files which are encrypted containers with the necessary installation software inside of them. There's one for the 32-bit version and one for the 64-bit version. When the media creation tool downloads the necessary ESD (or both, which can then be used to create a single 5.5GB ISO which has both of them on it simultaneously) it then decrypts the ESD containers and extracts the installation files which are THEN turned into an ISO.

When the media creation tool creates the ISO file, it does so by extracting those encrypted files contained within and as they're extracted and created on your machine, they are timestamped as expected - the reason you will always get different checksums is because of the timestamps.

If you create an ISO right now you'll get checksum A (as an example). If you wait 15 mins and create the ISO again, you'll get checksum B, and so on.

You will never get the same checksum twice in a row, so don't worry about that because it's not going to match.

If you look at your C: drive, you'll most likely find a directory (it's hidden so you may have to change your Explorer properties to see it) named $Windows.~WS

Inside that folder is another one named Sources, and inside that one will be a bunch of files as the download occurs. If you chose the 32-bit version, a file will be created called installx86.esd - if you chose the 64-bit version it'll be called installx64.esd - and if you chose both then both files will appear.

Those are the ESD files which get decrypted then turned into ISO files by the media creation tool.

As noted, because of timestamps, the checksums will always be different each time you create the ISOs from the ESD files so it's not a concern - the contents of the ISO files will be the same, just the files will have different timestamps which is why the checksums are always different.

Thanks for the detailed explanation. Seriously useful stuff

I once installed Windows 7 without running the ISO through a CheckSum cal and ended up with nothing but problems. Took me a while to figure out the OS was corrupt.