What is the so-called 'working CDM' in the context of widevine DRM?

[adidaz]

1. What is 'working CDM'?

2. How to decrypt the content key if the CDM is working?

3. How to know if a CDM is working?

4. Is it possible to use a legacy CDM?

5. How to dump the private key from a CDM?

[zackmark29]

LOL. there's a search button or google.

Or maybe here:
https://support.google.com/widevine/troubleshooter/6027072#ts=6035942
https://support.google.com/widevine/troubleshooter/6027072

[codehound]

1. What is 'working CDM'?

2. How to decrypt the content key if the CDM is working?

3. How to know if a CDM is working?

4. Is it possible to use a legacy CDM?

5. How to dump the private key from a CDM?

Here you go mate:

https://lmgtfy.app/#gsc.tab=0

[[ss]vegeta]

1. What is 'working CDM'?

2. How to decrypt the content key if the CDM is working?

3. How to know if a CDM is working?

4. Is it possible to use a legacy CDM?

5. How to dump the private key from a CDM?

1. Two specific files usually extracted from an android device. The one is a private key, the 2nd one is a blob, identifying the device. Working means that it wasn't banned and can be used to get decryption keys.
2. You need a script like WKS, Pywidevine or widevine_keys. Or something else.
3. Test it. Also, a CDM can work on some sites, but not on other sites. Sometimes the ban for a CDM is global, sometimes specific services ban it for their site.
4. Depends on what you mean by legacy but 99% of the time you can't.
5. This is a somewhat bad question because CDM here has another meaning but the basic answer is: by reverse engineering.

[adidaz]

1. What is 'working CDM'?

2. How to decrypt the content key if the CDM is working?

3. How to know if a CDM is working?

4. Is it possible to use a legacy CDM?

5. How to dump the private key from a CDM?

1. Two specific files usually extracted from an android device. The one is a private key, the 2nd one is a blob, identifying the device. Working means that it wasn't banned and can be used to get decryption keys.
2. You need a script like WKS, Pywidevine or widevine_keys. Or something else.
3. Test it. Also, a CDM can work on some sites, but not on other sites. Sometimes the ban for a CDM is global, sometimes specific services ban it for their site.
4. Depends on what you mean by legacy but 99% of the time you can't.
5. This is a somewhat bad question because CDM here has another meaning but the basic answer is: by reverse engineering.

Thank you for your detailed reply, bro!

Why android device? Is the private key extracted from an android device applicable for the CDM on my laptop? Sorry for my stupid question.

[[ss]vegeta]

Why android device? Is the private key extracted from an android device applicable for the CDM on my laptop? Sorry for my stupid question.

Because it's the easiest one to extract.
When you extract the CDM from an android device and you combine it with a script, the script mimics the android device.
Then when you send the server a license request and it gives you a response, it thinks you are an android device even though you are using a desktop/laptop.

[adidaz]

Why android device? Is the private key extracted from an android device applicable for the CDM on my laptop? Sorry for my stupid question.

Because it's the easiest one to extract.
When you extract the CDM from an android device and you combine it with a script, the script mimics the android device.
Then when you ask the server for a license request, it thinks you are an android device even though you are using a desktop/laptop.

Informative answer. Thanks a lot. I'll try.

[SE14man]

Got quite a few androids (Mostly Samsung and rooted with Magisk) from here onwards what else is needed? I am purely just trying to get my own keys and keen to try on each one of my rooted androids until i can get them.

Thanks.

[pkp]

This is a very basic illustration of how the system works

[ElCap]

Got quite a few androids (Mostly Samsung and rooted with Magisk) from here onwards what else is needed? I am purely just trying to get my own keys and keen to try on each one of my rooted androids until i can get them.

Thanks.

https://github.com/wvdumper/dumper

Android version: 7-9
OEM Crypto API version: 13 or less
this will show you the oem crypto api version
higher than that and you have to do some modifications to the dumper script

https://forum.videohelp.com/threads/404219-How-To-Dump-L3-CDM-From-Android-Device-s-%2...ing-L3-CDMS%29

[SE14man]

This is a very basic illustration of how the system works

Thanks for the image there.

There was a Github which showed instructions (if i remember rightly) of how to get the keys from an android. Though it seems sicne then that the github has since been removed.

Any ideas of where a guide could be for this method? All I want to do is just get my own keys

Thanks

[SE14man]

Sorry i didnt see your message up there. Thanks so much

[SE14man]

Got quite a few androids (Mostly Samsung and rooted with Magisk) from here onwards what else is needed? I am purely just trying to get my own keys and keen to try on each one of my rooted androids until i can get them.

Thanks.

https://github.com/wvdumper/dumper

Android version: 7-9
OEM Crypto API version: 13 or less
this will show you the oem crypto api version
higher than that and you have to do some modifications to the dumper script

https://forum.videohelp.com/threads/404219-How-To-Dump-L3-CDM-From-Android-Device-s-%2...ing-L3-CDMS%29

Thanks

[A_n_g_e_l_a]

This may be of use https://forum.videohelp.com/threads/404994-Decryption-and-the-Temple-of-Doom although much has been repeated above.

And something like this may also be useful?? Google search for:- site:forum.videohelp.com intext:l3 | CDM & Android

[ridibunda]

Because it's the easiest one to extract.
When you extract the CDM from an android device and you combine it with a script, the script mimics the android device.
Then when you send the server a license request and it gives you a response, it thinks you are an android device even though you are using a desktop/laptop.

So, Python script is some kind of Android emulator, but a little bit different (not like "Blue Stacks").

If those license servers were able to see MAC addresses, they would probably say "Damn same PCs are always sending requests, block them all"