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> the sender should just add non-repudiation to it in the form of a signature that's intended for that. Simple. Ok, but this does not magically happen if Googl

> the sender should just add non-repudiation to it in the form of a signature that's intended for that. Simple. Ok, but this does not magically happen if Google publishes and rotates their DKIM keys. People will continue to use email for everything, but now emails can no longer be authenticated by third parties.

hamburglar 6y ago
I think the entire point is that non-repudiation shouldn't just magically happen unless intended, so yes, this is by design, and anyone who wants to send a signed email should explicitly send a signed email.
- baobabKoodaa 6y ago
  > I think the entire point is that non-repudiation shouldn't just magically happen unless intended, so yes, this is by design, and anyone who wants to send a signed email should explicitly send a signed email. Let's not pretend that the world would move away from email if Google made this change. We both know that's not going to happen. Given that, can you explain why you think the world would be a better place when emails can be repudiated? When emails can be not be repudiated, innocent people can be framed for saying/doing things that they didn't do. DKIM protects innocent people from being framed. DKIM also protects innocent people against guilty people who commit frauds or other crime.
  - cakoose 6y ago
    First, "innocent people can be framed" is not that simple. Without non-repudiation, you don't automatically get to frame someone for whatever. You need to provide the usual (non-DKIM) evidence of whatever you're claiming. And even with non-repudiation, you can still try and frame someone. Not having the DKIM signature might be suspicious in some circumstances, but it doesn't eliminate the possibility. Second, "innocent" is not that simple. I don't want my private communication to become public, or publicly verifiable. That doesn't mean I'm not "innocent". This is not a fringe concept: https://en.wikipedia.org/wiki/Nothing_to_hide_argument https://en.wikipedia.org/wiki/Nothing_to_hide_argument "Give me six lines written by the most honest man in the world, and I will find enough in them to hang him." - Cardinal Richelieu
    - baobabKoodaa 6y ago
      > I don't want my private communication to become public, or publicly verifiable. That doesn't mean I'm not "innocent". This is not a fringe concept: https://en.wikipedia.org/wiki/Nothing_to_hide_argument https://en.wikipedia.org/wiki/Nothing_to_hide_argument Yes, I agree we should have secure private messengers. But that has nothing to do with this discussion. First off, email is not a secure private messenger. Second, email would not become "more secure" by removing the accidental, partial non-repudiation that DKIM provides. Third, this comment chain that you are replying in right now, is about whether there exists any legitimate need for a third party to authenticate emails with DKIM after the emails have been sent. tptacek claimed that no such legitimate need exists. I've been arguing against this with a specific counter-example.
      - hamburglar 6y ago
        "with DKIM" is the part of your argument you've failed to back up. Yes, you have a counter-example that requires authenticated emails. You don't have one that requires authenticating emails with DKIM.
        baobabKoodaa 6y ago
        > "with DKIM" is the part of your argument you've failed to back up. Yes, you have a counter-example that requires authenticated emails. You don't have one that requires authenticating emails with DKIM. That's because we aren't discussing a proposal to switch from DKIM authentication to a different method of authentication. We're discussing a proposal to abandon the partial non-repudiation property that's accidentally provided by DKIM, and replacing it with nothing.
        hamburglar 6y ago
        I'd argue that we currently have that "nothing" and are just trying to be explicit about it.
        6y ago
  - hamburglar 6y ago
    Nobody's talking about the world moving away from google. We're talking about the world simply not having non-repudiation built into email. A sender of an email doesn't owe you non-repudiation as a feature. Sorry if you think otherwise. Senders can add non-repudiation as a feature if they want to, which satisfies your purchase receipt scenario.
    - baobabKoodaa 6y ago
      > Nobody's talking about the world moving away from google. We're talking about the world simply not having non-repudiation built into email. A sender of an email doesn't owe you non-repudiation as a feature. Sorry if you think otherwise. Senders can add non-repudiation as a feature if they want to, which satisfies your purchase receipt scenario. Please explain to me how I can make Amazon (or any other webshop) add non-repudiable contracts to their order flow? That's right, I can't. And no, I don't think that Amazon "owes" me non-repudiable emails, but now that we have non-repudiation by accident, it's certainly nice to have, and the world would be worse off if we removed that feature and replaced it with nothing.
      - hamburglar 6y ago
        You can't force their DKIM signatures to be good forever either. You're basing some sense of security on a cryptographic property that simply isn't true. Would the world be worse off if you couldn't rely on DKIM signatures indefinitely? I don't know, are we worse off? Because whether you accept it or not, that's the exact situation we're in now.
        baobabKoodaa 6y ago
        So if something does not provide a perfect guarantee, it's "nothing"? You realize that handwritten signatures on a paper contract do not provide a perfect guarantee either? Signatures can be forged. And the paper is not going to remain in perfect condition forever, at some point in the future the paper is going to decay. Does that mean we can never know anything about anything? No. Of course we can have evidence about events which occurred in the world, even if the evidence doesn't provide a 100% guarantee of something, indefinitely. For example, a handwritten signature on a paper can be imperfect evidence that the contract took place, or a DKIM signature on an email can be imperfect evidence that the email is not a forgery.

hamburglar 6y ago

I think the entire point is that non-repudiation shouldn't just magically happen unless intended, so yes, this is by design, and anyone who wants to send a signed email should explicitly send a signed email.

baobabKoodaa 6y ago
> I think the entire point is that non-repudiation shouldn't just magically happen unless intended, so yes, this is by design, and anyone who wants to send a signed email should explicitly send a signed email. Let's not pretend that the world would move away from email if Google made this change. We both know that's not going to happen. Given that, can you explain why you think the world would be a better place when emails can be repudiated? When emails can be not be repudiated, innocent people can be framed for saying/doing things that they didn't do. DKIM protects innocent people from being framed. DKIM also protects innocent people against guilty people who commit frauds or other crime.
- cakoose 6y ago
  First, "innocent people can be framed" is not that simple. Without non-repudiation, you don't automatically get to frame someone for whatever. You need to provide the usual (non-DKIM) evidence of whatever you're claiming. And even with non-repudiation, you can still try and frame someone. Not having the DKIM signature might be suspicious in some circumstances, but it doesn't eliminate the possibility. Second, "innocent" is not that simple. I don't want my private communication to become public, or publicly verifiable. That doesn't mean I'm not "innocent". This is not a fringe concept: https://en.wikipedia.org/wiki/Nothing_to_hide_argument https://en.wikipedia.org/wiki/Nothing_to_hide_argument "Give me six lines written by the most honest man in the world, and I will find enough in them to hang him." - Cardinal Richelieu
  - baobabKoodaa 6y ago
    > I don't want my private communication to become public, or publicly verifiable. That doesn't mean I'm not "innocent". This is not a fringe concept: https://en.wikipedia.org/wiki/Nothing_to_hide_argument https://en.wikipedia.org/wiki/Nothing_to_hide_argument Yes, I agree we should have secure private messengers. But that has nothing to do with this discussion. First off, email is not a secure private messenger. Second, email would not become "more secure" by removing the accidental, partial non-repudiation that DKIM provides. Third, this comment chain that you are replying in right now, is about whether there exists any legitimate need for a third party to authenticate emails with DKIM after the emails have been sent. tptacek claimed that no such legitimate need exists. I've been arguing against this with a specific counter-example.
    - hamburglar 6y ago
      "with DKIM" is the part of your argument you've failed to back up. Yes, you have a counter-example that requires authenticated emails. You don't have one that requires authenticating emails with DKIM.
      - baobabKoodaa 6y ago
        > "with DKIM" is the part of your argument you've failed to back up. Yes, you have a counter-example that requires authenticated emails. You don't have one that requires authenticating emails with DKIM. That's because we aren't discussing a proposal to switch from DKIM authentication to a different method of authentication. We're discussing a proposal to abandon the partial non-repudiation property that's accidentally provided by DKIM, and replacing it with nothing.
        hamburglar 6y ago
        I'd argue that we currently have that "nothing" and are just trying to be explicit about it.
        6y ago
- hamburglar 6y ago
  Nobody's talking about the world moving away from google. We're talking about the world simply not having non-repudiation built into email. A sender of an email doesn't owe you non-repudiation as a feature. Sorry if you think otherwise. Senders can add non-repudiation as a feature if they want to, which satisfies your purchase receipt scenario.
  - baobabKoodaa 6y ago
    > Nobody's talking about the world moving away from google. We're talking about the world simply not having non-repudiation built into email. A sender of an email doesn't owe you non-repudiation as a feature. Sorry if you think otherwise. Senders can add non-repudiation as a feature if they want to, which satisfies your purchase receipt scenario. Please explain to me how I can make Amazon (or any other webshop) add non-repudiable contracts to their order flow? That's right, I can't. And no, I don't think that Amazon "owes" me non-repudiable emails, but now that we have non-repudiation by accident, it's certainly nice to have, and the world would be worse off if we removed that feature and replaced it with nothing.
    - hamburglar 6y ago
      You can't force their DKIM signatures to be good forever either. You're basing some sense of security on a cryptographic property that simply isn't true. Would the world be worse off if you couldn't rely on DKIM signatures indefinitely? I don't know, are we worse off? Because whether you accept it or not, that's the exact situation we're in now.
      - baobabKoodaa 6y ago
        So if something does not provide a perfect guarantee, it's "nothing"? You realize that handwritten signatures on a paper contract do not provide a perfect guarantee either? Signatures can be forged. And the paper is not going to remain in perfect condition forever, at some point in the future the paper is going to decay. Does that mean we can never know anything about anything? No. Of course we can have evidence about events which occurred in the world, even if the evidence doesn't provide a 100% guarantee of something, indefinitely. For example, a handwritten signature on a paper can be imperfect evidence that the contract took place, or a DKIM signature on an email can be imperfect evidence that the email is not a forgery.