4 ms·

I don't understand why short duration IP, DNS, SSL lifetimes. I would think that IPs, DNSs, SSL, lifetimes that go unchanged would imply more stability thus bet

I don't understand why short duration IP, DNS, SSL lifetimes. I would think that IPs, DNSs, SSL, lifetimes that go unchanged would imply more stability thus better reputation.

piperswe 4y ago
Short TLS certificate lifetimes mean that the CA checks to ensure the certificate owner actually controls the DNS once every 3 months, so it's less likely someone will have a certificate for a domain they only had control of for a temporary period.
- cm2187 4y ago
  And I think the rationale is also to force people to automate the process which is a good thing.
  - detourdog 4y ago
    I don't understand this sentiment. Once the process is automatic it won't be managed or monitored.
    - cm2187 4y ago
      Well, even large companies do a crap job at managing and monitoring the renewal of certificates manually. There has been many occurences of large companies (including Microsoft or Linkedin) leaving some certificate expire.
      - detourdog 4y ago
        Right and I don't expect them to manage an automatic process any better. I'm saying that there should be a form of trust for long standing stable environments.
- adql 4y ago
  You don't need to control the domain (only for wildcards), ability to serve under .well-known is enough.
tptacek 4y ago
TLS certificate revocation is an absolute clownfire and has been for 20+ years; short-duration certificates drastically mitigate the risk of stolen/misissued certificates.
- diarrhea 4y ago
  I like step-ca's approach to this, which is passive revocation. Their certs last 24h. That diminishes the use and also need of active revocation and all the associated baggage dramatically: just don't renew. I imagine this will be the way forward, slowly but surely. It's just that the public internet is too fragile for 24h windows... yet.
  - mcpherrinm 4y ago
    24 hours is likely a little too short; I would expect to see 3-10 day long certificates in the near future. Google Trust Services is already doing 3-day IP address certs, and Firefox doesn't do any revocation checks for certificates under 10 days: https://wiki.mozilla.org/CA/Revocation_Checking_in_Firefox#Short-Lived_Certificates https://wiki.mozilla.org/CA/Revocation_Checking_in_Firefox#S... Let's Encrypt has always been focused on automation to make shorter certificates a reality, and ARI is part of that plan. Shortening the lifetimes of the roots themselves is another thing that's coming, which is going to be harder for the world outside of auto-updating browsers to adopt. (I work at Let's Encrypt, but this is my own opinion)
    - witcH 4y ago
      Is there a future where IP certs are single use, burn-on-read?
      - mholt 4y ago
        Yes. We are aiming for that with Caddy. Starting with internal PKI. Caddy already has a built-in CA and ACME server, so it's just a matter of setting the lifetime to be very, very short. However, ultimately this will require TLS clients to implement proper support. For example, we already see problems in some web browsers where their TLS logic doesn't account for short lifetimes (like < 1 hour) and so page navs result in security errors because the cert has expired when actually all they have to do is renegotiate the TLS connection. It's debatable whether a cert needs to stay valid through the entire connection lifetime or just for establishing the connection. There is a performance penalty of doing this, of course, but for certain use cases it's acceptable.
dadrian 4y ago
You can mitigate things that go wrong quicker if the default lifetimes are shorter.
- detourdog 4y ago
  All of those are answers and possibly rationalizations. Seems to me an evil squatter could disrupt the system. The system is so automatic nobody needs to manage it.
- detourdog 4y ago
  I think this is a mistake they should be slowing down the system to gain reputation. Trying to keep pace with automatic spamming/hacking seems to be one possibility but longevity with no complaints should count for something.
aranchelk 4y ago
Early on I had the impression that short expiration probably made legacy CAs feel less threatened. Made Let’s Encrypt’s offering less comparable to those services —- prior to Let’s Encrypt, that business was basically: Step 1) get my root cert accepted everywhere. Step 2) print money. Step 3) Try not to get hacked, print more money.
schoen 4y ago
Some of the other replies have given the basic reasons; the original Let's Encrypt team was influenced by this paper, which stated some of those arguments more formally or academically: https://www.ieee-security.org/TC/W2SP/2012/papers/w2sp12-final9.pdf https://www.ieee-security.org/TC/W2SP/2012/papers/w2sp12-fin...

I don't understand why short duration IP, DNS, SSL lifetimes. I would think that IPs, DNSs, SSL, lifetimes that go unchanged would imply more stability thus better reputation.

piperswe 4y ago

Short TLS certificate lifetimes mean that the CA checks to ensure the certificate owner actually controls the DNS once every 3 months, so it's less likely someone will have a certificate for a domain they only had control of for a temporary period.

cm2187 4y ago
And I think the rationale is also to force people to automate the process which is a good thing.
- detourdog 4y ago
  I don't understand this sentiment. Once the process is automatic it won't be managed or monitored.
  - cm2187 4y ago
    Well, even large companies do a crap job at managing and monitoring the renewal of certificates manually. There has been many occurences of large companies (including Microsoft or Linkedin) leaving some certificate expire.
    - detourdog 4y ago
      Right and I don't expect them to manage an automatic process any better. I'm saying that there should be a form of trust for long standing stable environments.
adql 4y ago
You don't need to control the domain (only for wildcards), ability to serve under .well-known is enough.

tptacek 4y ago

TLS certificate revocation is an absolute clownfire and has been for 20+ years; short-duration certificates drastically mitigate the risk of stolen/misissued certificates.

diarrhea 4y ago
I like step-ca's approach to this, which is passive revocation. Their certs last 24h. That diminishes the use and also need of active revocation and all the associated baggage dramatically: just don't renew. I imagine this will be the way forward, slowly but surely. It's just that the public internet is too fragile for 24h windows... yet.
- mcpherrinm 4y ago
  24 hours is likely a little too short; I would expect to see 3-10 day long certificates in the near future. Google Trust Services is already doing 3-day IP address certs, and Firefox doesn't do any revocation checks for certificates under 10 days: https://wiki.mozilla.org/CA/Revocation_Checking_in_Firefox#Short-Lived_Certificates https://wiki.mozilla.org/CA/Revocation_Checking_in_Firefox#S... Let's Encrypt has always been focused on automation to make shorter certificates a reality, and ARI is part of that plan. Shortening the lifetimes of the roots themselves is another thing that's coming, which is going to be harder for the world outside of auto-updating browsers to adopt. (I work at Let's Encrypt, but this is my own opinion)
  - witcH 4y ago
    Is there a future where IP certs are single use, burn-on-read?
    - mholt 4y ago
      Yes. We are aiming for that with Caddy. Starting with internal PKI. Caddy already has a built-in CA and ACME server, so it's just a matter of setting the lifetime to be very, very short. However, ultimately this will require TLS clients to implement proper support. For example, we already see problems in some web browsers where their TLS logic doesn't account for short lifetimes (like < 1 hour) and so page navs result in security errors because the cert has expired when actually all they have to do is renegotiate the TLS connection. It's debatable whether a cert needs to stay valid through the entire connection lifetime or just for establishing the connection. There is a performance penalty of doing this, of course, but for certain use cases it's acceptable.

dadrian 4y ago

You can mitigate things that go wrong quicker if the default lifetimes are shorter.

detourdog 4y ago
All of those are answers and possibly rationalizations. Seems to me an evil squatter could disrupt the system. The system is so automatic nobody needs to manage it.
detourdog 4y ago
I think this is a mistake they should be slowing down the system to gain reputation. Trying to keep pace with automatic spamming/hacking seems to be one possibility but longevity with no complaints should count for something.

aranchelk 4y ago

Early on I had the impression that short expiration probably made legacy CAs feel less threatened. Made Let’s Encrypt’s offering less comparable to those services —- prior to Let’s Encrypt, that business was basically: Step 1) get my root cert accepted everywhere. Step 2) print money. Step 3) Try not to get hacked, print more money.

schoen 4y ago

Some of the other replies have given the basic reasons; the original Let's Encrypt team was influenced by this paper, which stated some of those arguments more formally or academically: https://www.ieee-security.org/TC/W2SP/2012/papers/w2sp12-final9.pdf https://www.ieee-security.org/TC/W2SP/2012/papers/w2sp12-fin...