Film-Tech Forum ARCHIVE: Erased the DCP O MATIC file, can I still make up a KDM?

This is topic Erased the DCP O MATIC file, can I still make up a KDM? in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Cameron Glendinning (Member # 3516) on 10-11-2018, 11:58 PM:

I just realized I have erased the DCP O MATIC programme file, I have kept the encryption code numbers involved as a text file. Is it somehow possible to make up a new KDM for the DCP that I have stored on a hard drive?

Posted by Leo Enticknap (Member # 534) on 10-12-2018, 11:22 AM:

quote: DCP-o-Matic Manual
You must be careful when using encryption not to lose important keys.

If you are making KDMs from a DCP-o-matic film you must ensure that you have a backup of the metadata.xml file from the project, as well as the DCP itself.

If you are using a DKDM you must ensure that you have a backup of DCP-o-matic's config.xml file, since it contains the only key which can decrypt the DKDM. The config.xml file location depends on your operating system; possible locations are listed in Chapter 18, Configuration files

Posted by Ioannis Syrogiannis (Member # 3235) on 10-12-2018, 11:28 AM:

Wouldn't that have a faster answer in the DCP-o-matic forum?

You can head to dcpomatic.com and click on help, then follow the forum link. For some reason, the forum link is not on the first page...

P.S. Leo gave a full response while I was searching the way to not use a link...

Posted by Cameron Glendinning (Member # 3516) on 10-12-2018, 04:03 PM:

Thank you for the reply's, I kinda knew I was wishful thinking when I posted but it was worth asking
.

Posted by Carl Hetherington (Member # 7107) on 10-12-2018, 04:12 PM:

As others have said, the DCP-o-matic forum would probably get you a quicker answer!

What do you mean by "encryption code numbers"? You might be able to make a KDM with them, depending on what they are...

Posted by Carsten Kurz (Member # 5396) on 10-12-2018, 05:58 PM:

Cameron - you may have erased your DCP-o-matic installation, but your config file including the certs is probably still there. Do you still have the project directory where the encrypted DCP was created?

- Carsten

Posted by Randy Stankey (Member # 64) on 10-12-2018, 05:58 PM:

What, exactly, did you delete?

If you simply deleted the application file but not the prefs/settings folder(s) then you should be able to find those folders, temporarily rename them, reinstall the application then move the original files back to their rightful place and you should be okay.

Think of what you would have to do when you want to reinstall an application like Firefox without losing all your bookmarks, passwords and settings. The process would be similar.

However, if you deleted everything, including your prefs folder, you will have a tougher problem to solve. You’ll have to recover all your encryption keys and reinstall them before you can encrypt files or play back encrypted files.

If you can’t recover your keys, you’re basically hosed.

Posted by Cameron Glendinning (Member # 3516) on 10-14-2018, 04:06 PM:

Hi all

I have only created one file that needed a KDM, I still have DCP O Matic as working software on my computer. I kept the file that actually ingests and plays in the projector but erased the rest of the files for that project.

I did keep a text file of the actual code used for the encryption which I suspect is worthless.

Posted by Carl Hetherington (Member # 7107) on 10-14-2018, 05:50 PM:

What do you mean by "actual code used for the encryption"? The 32-digit code from the metadata.xml?

Posted by Carsten Kurz (Member # 5396) on 10-15-2018, 03:51 AM:

I guess he wrote down the encryption data string that he either input or had generated manually under the DCP tab (and that went to the - lost - metadata file). So, technically, he has everything he needs to decrypt that DCP, but which tools will allow him to create a KDM from that?

asdcplib will allow to decrypt the assets using the raw key, but that process is a bit cumbersome.

Can he create a fake metafile for an encrypted DCP and edit that key into it? Then how can he assign the CPL/UUID of the existing DCP in order to see it as target for KDM creation?

- Carsten