MUK and Masterpassword and Keysets question

sooooo.... I get that my old master password can be used to unlock my old key set if such a copy existed and I don’t think it does... you don’t have one and you don’t seem to imply that I have it anymore after the change (right). I’m not the target of a nationstate and nobody knew I was downloading u guys that night lol.

Here’s the question , I didn’t use the strongest master password when setting up my account so I wouldn’t lock myself out. Did I inadvertently create a weak muk since it has no bearing on my much stronger current password ? Or does it somehow not matter?

Ty. Hope that makes sense...

1Password Version: Not Provided
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  • rickfillionrickfillion Junior Member

    Team Member

    You win the "forum post subject line that gets rick excited the most" award today! I love being given an excuse to talk about these things.

    Let's see if I can answer your question to your satisfaction...

    Since you're talking about keysets, I assume you're specifically asking about accounts. Everything I'm about to state applies to accounts, and if I'm making a bad assumption let me know and I'll get you another answer.

    What's stored on our server, and what's sent to client apps is your keyset(s), encrypted by the MUK. The MUK (Master Unlock Key for anyone following at home) is the encryption key that's derived from your email address (considered public info), your Master Password, and your Secret Key.

    Due to the Secret Key, the strength of the MUK isn't going to vary that much based on your Master Password. A really strong human generated Master Password is estimated to have the equivalent of something like 40bits of entropy. Whereas the Secret Key has 128. So 128 + 40 vs say 128 + 10... it's not significantly different. If the Secret Key was kept secure then it's probably fine.

    Let's go over what happens when you change your Master Password in, which happens to be basically the same thing that happens when you regenerate a new Secret Key (both are available to you under My Profile of the webapp):

    • The client will make sure that you know your current MP, then prompt you for a new MP.
    • The computes a new MUK based on the Email, Secret Key, New Master Password
    • Generates a new set of SRP Auth parameters
    • Encrypts your current active keyset (the one used to encrypt/decrypt anything you have access to) with the new MUK
    • Sends it (SRP Auth params, new encrypted keyset) to the server, encrypted with the current session encryption key
    • Our server overwrites the old value in our database

    So by changing your Master Password, you changed your MUK, and re-encrypted the keyset with the new MUK.

    You're technically right that someone who could get their hands on the keyset, encrypted with the original MUK could decrypt it with the original MUK if they could derive it. The secret key should make that computationally infeasible.

    I hope this helps. Let me know if you have any more questions.


  • Lol. No you understood. And it was for accounts. I think perhaps I missread the teams white paper though I have an individual account. Somewhere along the line between white paper and some searching and in the form I thought the MUK remained unchanged. Could be I’m talking about something entirely different that didn’t change after the first creation.... I don’t know... lol irl as I write this.

    And referring to the white paper I don’t know anybody who is brave enough to do HtTps pinning for what little extra it gives you... I think last year only something like three or 400 sites were using it. Done badly you brick your business from all old visitors for the next six months....

    Appreciate ‘the award’ :)

  • rickfillionrickfillion Junior Member

    Team Member

    Somewhere along the line between white paper and some searching and in the form I thought the MUK remained unchanged

    The MUK definitely changes, but the keyset does not (currently). The whitepaper does mention the fact that user keysets, group keysets, and vault keys currently don't change over time. The MUK would need to change because the MUK isn't ever stored anywhere. It's something that's derived from other bits of information, and so when one of those bits changes, it too needs to change.

    I don’t know anybody who is brave enough to do HtTps pinning for what little extra it gives you

    Amen. I quite like the fact that we don't depend on TLS alone to protect the communication. As you said, the risk to reward ratio for pinning has always seemed just too bad to me.

    Don't hesitate to send more questions our way. Have yourself a great afternoon.


  • Appreciate the response and let me just rephrase my question and use user keyset instead of muk. Did I goof by using a weak master password and did that play in the creation/derivation of my public/private key. I might be missing it in the white paper, but I would hate the thought of a dumdum error and flaw in using this platform.


  • rickfillionrickfillion Junior Member

    Team Member

    @AlwaysSortaCurious : the user keyset is always created completely randomly generated. Though technically the encrypted form of it was once encrypted using the MUK with the weaker password, due to the extra strength of the secret key i don't think it's a worry.

    If you want to be 1000% safe, you could always create a new account though. But I don't think it's really necessary.


  • Thanks. yeah, no one is after me and that old keyset is nowhere to be found. Thanks!

  • rickfillionrickfillion Junior Member

    Team Member



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