Give user write permissions based on meta data tag (s)

Question

Ex:

• The organisation do not have access to write back to AD
• Everybody (users) in a organisation have read permission on every document / library / site etc.

Based on "something magic" (list / user permission / token ... ) is there a way to give write permission based on a meta data tag?

If a document got the tag "CAR" the user "X" got persmission to write to the document?

Sombody have mention:

• C2WTS
• itemReciever (custom check ONLY when a documents gets open)
• http://www.youtube.com/watch?v=X4rzQ6ufBnI

There is a third party that seems to have this: -http://www.titus.com/software/sharepoint/metadata.php

Answer 1

It's not available out of the box.

But you have a number of options:

Put documents in folders with unique permissions
If it's a single value that determines who can change the document then you can:

• Create a number of folders (one for each value)
• On each folder break permission inheritance
• Give the right people write access
• Place the documents in the right of these folders based on the value

Unique Permissions
If your world is more complex then you need code either an event receiver or a workflow which breaks inheritance on each item and assigns the right group of people the write access.
In this case be aware the performance degrades when you have a lot of unique permissions.