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How modern computing quietly depends on this constantly-maintained layer of trust infrastructure

embedding-shape 8mo ago
Well, to be more specific, "modern internet/web". Most of the applications that ran on a Windows XP computers still run on a Windows XP computer without hiccups, unless they do a lot of network connectivity for the functionality.
grishka 8mo ago
And no one can even give a concrete answer why root certificates need expiration dates. It's just because reasons. IMO the whole PKI thing is a terrible idea to begin with. It would make much more sense to tie the trust in TLS to DNS somehow, since the certificates themselves depend on domains anyway. Then you would only have a single root of trust, and that would be your DNS provider (or the root servers). And nothing will expire ever again.
- westurner 8mo ago
  Root certificates need expiration dates for the same reason that LetsEncrypt certs need an expiration date: risk of cert compromise and forgery increases over time. Over a long enough timeline, there will be vulns discovered in so much of the software that guards the CA certs in RAM
  - grishka 8mo ago
    > risk of cert compromise and forgery increases over time. And what if the certificate is compromised before it expires? Right, there's a revocation mechanism for that. So why expire them then if they can be revoked anyway IF they get compromised? The reason why domain TLS certificates expire is that domains can change owners. It makes sense that it should not be possible for someone to buy a domain for one year, get a non-expiring TLS certificate issued for it, and then have the ability to MitM its traffic if it ever gets bought by someone else later. Domain certificates are sent as part of the connection handshake, so them expiring is unnoticeable for the end users. However, root certificates rely on the OS getting updates forever, which is unsustainable. Some systems lack the ability to install user-provided root CAs altogether, and some (Android) do allow it but treat them as second-class.
    - grosswait 8mo ago
      Because the most dangerous secret is one that has been compromised and you don’t know it. This sets a time limit for their usefulness. Sometimes the stories about terrible default choices that are insecure sink in and architects choose a better path.
      - lokar 8mo ago
        Also, details about the certs and the standards for them change over time. This makes it easier for the browser venders (via the CA forum) to force cert providers to update over time.
        grishka 8mo ago
        You're talking about it like they change by the force of nature, not because humans change them.
    - snailmailman 8mo ago
      The revocation mechanism is basically just a list of revoked certificates. Without expiration dates, those lists will grow infinitely.
- plq 8mo ago
  Certificates need expiration dates to be able to garbage collect certificate revocation lists.
  - wtallis 8mo ago
    Do certificate revocation lists need to keep including certificates that have long since expired? I don't see why root certificates need to expire as long as the certificates signed by those roots all have reasonable expiration windows, unless someone is doing something strange about trusting formerly-valid certificates, or not checking root certificates against revocation lists.
- snowwrestler 8mo ago
  Right, because DNS entries never expire.
  - grishka 8mo ago
    Of course they do, they have to. But it's okay for things that are sent to you over the network to expire. It's not okay for things built into your potentially abandoned OS to expire.
    - snowwrestler 8mo ago
      > Of course they do, they have to. Why do they have to? (This will also tell you why certs in your OS need to expire.)
      - grishka 8mo ago
        Because domains change owners. https://news.ycombinator.com/item?id=47074127 https://news.ycombinator.com/item?id=47074127
        snowwrestler 8mo ago
        More specifically: because they cannot be revoked, they need to expire. Same with root certs.
- burnte 8mo ago
  The instant we bound encrypted connections with identity we failed. And decades later we're still living with the mistake. I'm completely serious when we need to abandon the ID verification part of certificates. That's an entirely separate problem from encryption protocol. An encryption protocol needs absolutely no expiration date, it's useful until it's broken, and no one can predict that. Identity should be verified in a separate path.

Well, to be more specific, "modern internet/web". Most of the applications that ran on a Windows XP computers still run on a Windows XP computer without hiccups, unless they do a lot of network connectivity for the functionality.

grishka 8mo ago

And no one can even give a concrete answer why root certificates need expiration dates. It's just because reasons. IMO the whole PKI thing is a terrible idea to begin with. It would make much more sense to tie the trust in TLS to DNS somehow, since the certificates themselves depend on domains anyway. Then you would only have a single root of trust, and that would be your DNS provider (or the root servers). And nothing will expire ever again.

westurner 8mo ago
Root certificates need expiration dates for the same reason that LetsEncrypt certs need an expiration date: risk of cert compromise and forgery increases over time. Over a long enough timeline, there will be vulns discovered in so much of the software that guards the CA certs in RAM
- grishka 8mo ago
  > risk of cert compromise and forgery increases over time. And what if the certificate is compromised before it expires? Right, there's a revocation mechanism for that. So why expire them then if they can be revoked anyway IF they get compromised? The reason why domain TLS certificates expire is that domains can change owners. It makes sense that it should not be possible for someone to buy a domain for one year, get a non-expiring TLS certificate issued for it, and then have the ability to MitM its traffic if it ever gets bought by someone else later. Domain certificates are sent as part of the connection handshake, so them expiring is unnoticeable for the end users. However, root certificates rely on the OS getting updates forever, which is unsustainable. Some systems lack the ability to install user-provided root CAs altogether, and some (Android) do allow it but treat them as second-class.
  - grosswait 8mo ago
    Because the most dangerous secret is one that has been compromised and you don’t know it. This sets a time limit for their usefulness. Sometimes the stories about terrible default choices that are insecure sink in and architects choose a better path.
    - lokar 8mo ago
      Also, details about the certs and the standards for them change over time. This makes it easier for the browser venders (via the CA forum) to force cert providers to update over time.
      - grishka 8mo ago
        You're talking about it like they change by the force of nature, not because humans change them.
  - snailmailman 8mo ago
    The revocation mechanism is basically just a list of revoked certificates. Without expiration dates, those lists will grow infinitely.
plq 8mo ago
Certificates need expiration dates to be able to garbage collect certificate revocation lists.
- wtallis 8mo ago
  Do certificate revocation lists need to keep including certificates that have long since expired? I don't see why root certificates need to expire as long as the certificates signed by those roots all have reasonable expiration windows, unless someone is doing something strange about trusting formerly-valid certificates, or not checking root certificates against revocation lists.
snowwrestler 8mo ago
Right, because DNS entries never expire.
- grishka 8mo ago
  Of course they do, they have to. But it's okay for things that are sent to you over the network to expire. It's not okay for things built into your potentially abandoned OS to expire.
  - snowwrestler 8mo ago
    > Of course they do, they have to. Why do they have to? (This will also tell you why certs in your OS need to expire.)
    - grishka 8mo ago
      Because domains change owners. https://news.ycombinator.com/item?id=47074127 https://news.ycombinator.com/item?id=47074127
      - snowwrestler 8mo ago
        More specifically: because they cannot be revoked, they need to expire. Same with root certs.
burnte 8mo ago
The instant we bound encrypted connections with identity we failed. And decades later we're still living with the mistake. I'm completely serious when we need to abandon the ID verification part of certificates. That's an entirely separate problem from encryption protocol. An encryption protocol needs absolutely no expiration date, it's useful until it's broken, and no one can predict that. Identity should be verified in a separate path.