How can end-to-end encryption works for multiple devices?


If i’m not wrong, Bitwarden uses end-to-end encryption ? Yet, it is still possible to connect from any device or web browser and access all our passwords from anywhere.

How is it possible, since Bitwarden doesn’t our password and therefore cannot compare with the one used to connect from a new device ? In the end, what I would like to know is how end-to-end encryption can work for multiple devices.

Could someone explain that with simple words, for curious beginners ?

Thank you.

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It works because your multiple devices are syncing with the Bitwarden Vault in the Azure cloud service they use. BW uses a zero knowledge approach, which means NO data leaves your devices until it is encrypted locally on the device. The encrypted package is sent to the BW cloud. Even the BW team cannot possibly decrypt your information because ONLY you know the password to decrypt the file. So in essence your cloud held BW vault is the master file. All connected devices will sync with that service. That means that when you log on from a device,the totally encrypted data is sent down to you and then you must decrypt it on your local device.

As an example on my end - If I went to a new device and installed the BW app I could open my vault on the device. I would need my username, password, and U2F (2FA) key to authenticate before the file would be sent down. It comes down encrypted and again it is decrypted locally. That is how it works across devices and maintains security during the process. The cautionary warning is that because the process is zero knowledge for BW you MUST maintain your own access. If you forget your codes they CANNOT help you in any way.

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Which is what made me believe the service is trustworthy (as opposed to other service where they have the keys to unlock your vault if you lock yourself out).

Would you agree with that @OpSec?


I absolutely agree that ANY security service should be set to zero knowledge on “their” part. If any service provider can access your stuff at their discretion you know that someone is eventually going to abuse that elevated privilege. Sounds harsh but if users are adults then they should be responsible for their accounts. If you lose your keys and don’t have an established backup plan then are you REALLY being an adult?

This is also true for the self-hosted versions. I was foolishly researching things like “how can our admins change the password of a user?”, but it’s impossible, of course! If a user forgets their master password, their encrypted info is gone forever. The only option is to delete the user and create it again :slight_smile: If an admin could set the master passphrase for someone, they could also use it to log in and read that user’s existing passwords, but BitWarden makes this absolutely impossible.

That’s how it should be, IMO, your encrypted data is yours and no one else’s.