Quote:
Originally Posted by kovidgoyal
I remember looking at this a while back and coming away with the impression that adobe has the ability to use plugins for encryption, so it's highly unlikely that the password based encryption and the particular encryption that an ebook uses is the same.
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Elcomsoft claims (on their web site) that their "Advanced PDF Password Recovery" suite is capable of decrypting encrypted PDF documents so long as plug-in encryption is not used. From what I can tell, there is a built-in encryption scheme which can use either a 40-bit or 128-bit key, as well as the option for using 3rd party plug-ins for the encryption.
I have not run across enough encrypted PDF documents to have any idea how widespread plug-ins are versus the default built-in encryption, but would be curious to find out if anyone can shed any light... Presumably if one were sufficiently widespread, Elcomsoft might consider adding support for it in a future release -- after all, this is what they specialise in.