diff options
author | Daniel Stenberg <daniel@haxx.se> | 2021-02-05 10:50:51 +0100 |
---|---|---|
committer | Daniel Stenberg <daniel@haxx.se> | 2021-02-05 10:50:51 +0100 |
commit | a52247548b3f439f1508d90c1a6e402409d470c2 (patch) | |
tree | 10b2d8018768b308254b3ab8a01af3627d0fb776 | |
parent | 6cd167a0dc1c2a92cd4929e2fddd9d0742a58f5a (diff) | |
download | curl-bagder/ssl-probs.tar.gz |
docs/SSL-PROBLEMS: enhancedbagder/ssl-probs
Elaborate on the intermediate cert issue, and mention that anything
below TLS 1.2 is generally considered insecure these days.
-rw-r--r-- | docs/SSL-PROBLEMS.md | 17 |
1 files changed, 14 insertions, 3 deletions
diff --git a/docs/SSL-PROBLEMS.md b/docs/SSL-PROBLEMS.md index cd17cd615..bc3c1d52c 100644 --- a/docs/SSL-PROBLEMS.md +++ b/docs/SSL-PROBLEMS.md @@ -23,8 +23,18 @@ ## CA bundle missing intermediate certificates When using said CA bundle to verify a server cert, you will experience - problems if your CA cert does not have the certificates for the - intermediates in the whole trust chain. + problems if your CA store does not contain the certificates for the + intermediates if the server doesn't provide them. + + The TLS protocol mandates that the intermediate certificates are sent in the + handshake, but as browsers have ways to survive or work around such + omissions, missing intermediates in TLS handshakes still happen that + browser-users won't notice. + + Browsers work around this problem in two ways: they cache intermediate + certificates from previous transfers and some implement the TLS "AIA" + extension that lets the client explictly download such cerfificates on + demand. ## Protocol version @@ -36,7 +46,8 @@ An additional complication can be that modern SSL libraries sometimes are built with support for older SSL and TLS versions disabled! - All versions of SSL are considered insecure and should be avoided. Use TLS. + All versions of SSL and the TLS versions before 1.2 are considered insecure + and should be avoided. Use TLS 1.2 or later. ## Ciphers |