Why can old version decrypt AES-128?

[Guest mrossk]

I have updated to the newest version of Evernote for Windows Desktop 5.1.1.2334 and encrypted some text.

 

I exported this note and opened it in a text editor and I could find: cipher="AES" length="128". So it really seems to be encrypted with AES-128.

 

Then I synced this note to an other computer with an older version of Evernote for Windows Desktop and to my surprise I was able to decrypt this new encrypted text on this older version.

 

Now I am a little unsecure: Is this text really encrypted with AES-128? Or has older versions of Evernote for Windows Desktop already been able to decrypt AES-128?

 

Marcel.

[jbenson2 2,147]

That's a good question.

 

Evernote has not been very outgoing with detailed information on this long-awaited security improvement. There have been some sharp-eyed users who have tried to piece together some of the behind-the-scenes activity. One comment mentioned that it appears the encryption might only be for the Evernote servers. I believe it does involve both their servers and our clients, but I'm not a security expert.

 

Here is a comment from Evernote staff that caused some confusion.

"To you guys, there shouldn't be any change. But on our side we're now using AES-128."

 

Here is a link with more details, including a short followup reply from Evernote.

http://discussion.evernote.com/topic/51794-511-rc/

 

He mentions:

"It update it, you should update the text you have encrypted."

 

I could be wrong, but I believe he means that previously encrypted text needs to be edited (changed) and re-encrypted to take advantage of the improved security. You can find all your encrypted notes by using a search for

"encryption:".

 

I have a couple hundred encrypted notes. I don't see an easy way to identify which encryption method is used (the easily broken 64-bit RC2 vs the tougher 128-bit AES). Hopefully more details will be released by Evernote to give us a better understanding on what we need to do to take advantage of this improved security.

[Guest mrossk]

Can someone from Evernote explain why it has been possible to decrypt AES-128 encrypted text with an older version of Evernote that has not supported AES-128?

 

I want to know if I can trust this encryption to store some sensitive information.

 

Thanks.

 

Marcel.

[ScottLougheed 1,316]

While Evernote staff do read these forums, this is by and large a user forum. If you want a surefire response from Evernote staff to a given question, I suggest you open a support ticket. 

 

That said, I am sure your fellow users would be interested in what the answer is and would appreciate you coming back here to share Support's response!