Running one’s own root Certificate Authority in 2023 • Hacker News Board

Re: Running one’s own root Certificate Authority in 2023

#81

Post by 1vuio0pswjnm7 » Sun, Sep 17, 2023, 6:14 AM UTC

Trivia question: What is the limit, if any, for how many DNS names (SANs) one can include in a single self-signed certificate. It is common to see TLS proxies that will generate certificates on the fly as SNI in clientHell is received. Is this due to a limit on how many SANs one can include in a single certificate.

(Maybe the performance degradation of generating a certificate on the fly is less than using a certificate that includes 100s of SANs.)

Re: Running one’s own root Certificate Authority in 2023

#82

Post by wejn » Sun, Sep 17, 2023, 6:24 AM UTC

firesteelrain wrote: post #49

HashiCorp Vault supports being an ACME server. Why not use that?

Because:

1. ACME is a dumpster fire prone to mitm attacks.

2. without HSM (an additional investment) it's super bad idea to host your root CA signing key somewhere.

Re: Running one’s own root Certificate Authority in 2023

#83

Post by wejn » Sun, Sep 17, 2023, 6:27 AM UTC

e12e wrote: post #69

"Only" missing how to safely distribute, trust and revoke/renew the root cert - and how to enforce/distribute revocation lists for certs...

"only" out of scope.

But based on the comments here, I guess you could use the smallstep CA with Nitrokey HSM if that's your jam...

Re: Running one’s own root Certificate Authority in 2023

#84

Post by remram » Sun, Sep 17, 2023, 6:32 AM UTC

I tend to treat service TLS certificates more like shared keys than PKI. Too many pieces of software don't handle revocation, it's easier to regenerate the CA and the entire set of certificates when you change your setup.

Re: Running one’s own root Certificate Authority in 2023

#85

Post by chrisweekly » Sun, Sep 17, 2023, 6:35 AM UTC

1vuio0pswjnm7 wrote: post #81

Trivia question: What is the limit, if any, for how many DNS names (SANs) one can include in a single self-signed certificate. It is common to see TLS proxies that will generate certificates on the fly as SNI in clientHell is received. Is this due to a limit on how many SANs one can include in a single certificate. (Maybe the performance degradation of generating a certificate on the fly is less than using a certific…

I think user-perceptible performance degradation might set a lower practical ceiling than purely technical limitations would. I've seen as many as ~200 SANs on a single cert -- but I'm not claiming any special expertise or insights.

Re: Running one’s own root Certificate Authority in 2023

#86

Post by galaxyLogic » Sun, Sep 17, 2023, 6:36 AM UTC

Is there an Open Source program I could just run on the command-line, to have my own Certificate Authority? Or just to create a certificate?

Or do I need to know all the gory details myself?

Re: Running one’s own root Certificate Authority in 2023

#87

Post by rurban » Sun, Sep 17, 2023, 6:38 AM UTC

galaxyLogic wrote: post #86

Is there an Open Source program I could just run on the command-line, to have my own Certificate Authority? Or just to create a certificate? Or do I need to know all the gory details myself?

mkcert is the easiest

Re: Running one’s own root Certificate Authority in 2023

#88

Post by infogulch » Sun, Sep 17, 2023, 6:42 AM UTC

jordemort wrote: post #17

I really like step[1] and step-ca[2] for this, it's a lot less fiddly than having to drive OpenSSL directly. 1. https://github.com/smallstep/cli 2. https://github.com/smallstep/certificates

Wouldn't it be nice if LetsEncrypt could issue you a (1) name constrained, (2) 90-day limited intermediate CA with just the (3) DNS-01 challenge? I argue that such an intermediate CA would have no more authority than a wildcard cert which you can get today, so they should be able to issue it. [1] Everything supports name constraints now, which used to be an issue but isn't anymore. [2]

Then stick it in step-ca and issue all your certificates with internal ACME.

This would solve a lot of problems, such as leaking private hostnames in the certificate transparency log, or hitting issuance rate limits on LE servers.

[1]: https://news.ycombinator.com/item?id=29811552

[2]: https://bettertls.com/

Re: Running one’s own root Certificate Authority in 2023

#89

Post by galaxyLogic » Sun, Sep 17, 2023, 7:08 AM UTC

I'm building an app whose GUI runs in the browser talking to a local http server. The app (if and when it is ready) would be distributed as a standalone executable. A bit like Atom/Electron I guess.

What I haven't figured out yet is how the browser-GUI could talk to its local backend-server over https. Can an exe contain its own root-certificate-authority somehow in a way that the app-exe can work without having to update that certificate part ever?

Re: Running one’s own root Certificate Authority in 2023

#90

Post by entuno » Sun, Sep 17, 2023, 7:22 AM UTC

1vuio0pswjnm7 wrote: post #81

Trivia question: What is the limit, if any, for how many DNS names (SANs) one can include in a single self-signed certificate. It is common to see TLS proxies that will generate certificates on the fly as SNI in clientHell is received. Is this due to a limit on how many SANs one can include in a single certificate. (Maybe the performance degradation of generating a certificate on the fly is less than using a certific…

I'm sure sure about a hard limit in the x509 standard (would need to dig into the RFCs) - but the BadSSL site has two test domains that have certificates with 1,000 and 10,000 SANs respectively:

https://1000-sans.badssl.com

https://10000-sans.badssl.com

1,000 works in Firefox and Chromium, but 10,000 gives `SSL_ERROR_RX_MALFORMED_HANDSHAKE` in Firefox, and `ERR_SSL_PROTOCOL_ERROR` in Chromium. OpenSSL won't connect to it either - it gives `read_state_machine:excessive message size:ssl/statem/statem.c:610`

So in practical terms, the answer seems to be somewhere between the 1,000 and 10,000.