[eschwartz]

Originally Posted by cybmole

so you reckon that once a device or PC has been authorised, then it STAYS authorised even if you change the web site password.

I'm fairly certain. It is how many things like this work.

Someone seems to have asked this question at Adobe Help already, here: http://forums.adobe.com/message/5749904

I agree with the answerer's logic -- "I think (not sure) that once the authorization has been made to the underlying AdobeID, that authorization remains.
The device doesn't recheck the current password (or even the current email) associated with the AdobeID, and things just go on working."

In any event, that poster confirms "I had to change my Adobe password recently (after the breach in the Adobe security) and didn't change anything on either my Sony device or ADE."

so how does a purchased book check work. If send a purchased book to a new reader, does the reader just do an ID check i.e. checks that is has the same adobe-ID as is embedded in the book somewhere, & then says OK you can read that

that would be terribly insecure. A reader that doesn't follow Adobe's rules would just say "I'll let you read it anyway". What it does is encrypt the book with a key that is stored on the device. ADE reads the device, confirms it is authorized with the same Adobe ID and then re-encrypts the book with the devices encryption key.

The device tries to read all books using its encryption key. If the book was sent via ADE, the key will "fit" in the books encryption and the file can be read. Otherwise you have a file full of gibberish which cannot be read.

But that's just the technical mumbo-jumbo. The point is, once a book has been sent, the device can read it until it is deleted (or expires, I suppose). Re-sending it will need to go through the check, but ADE will handle that.

Am i right in thinking that you don't ever give your adobe credentials to an e-book store, you just buy the acsm licence file & then it is your PC or device that associates an adobe ID with that purchase , when it opens the acsm & downloads the actual book?.

Absolutely. You got it!

so you don't need to know your adobe password in order to buy a book, so long as you buy via an already authorised device.

You just need to open the acsm with software that can verify acsm's, and has been authorized. ADE can do that, as can some readers. I think the Sony reader can. B&N and Kobo will give you their own processed copy, but ou can download the acsm from their website.

and I could buy , but not open, an acsm file & give it to someone ellse, or vice-verse . it is a "good for one use only" file, and is linked to a specific ID only when 1st opened ?

Absolutely. You got it!