Clarify: tls_verify_certificates is for CA certs.

It can be used for individual user certs but is really intended for
CAs.  Note this, and explain that if the tls_verify_certificates value
is a file, then the certs within are sent from the server to clients,
thus is public data.

diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt
index 15b3a2b896ebe271094a206a8bfb17c1a5fa0b1a..160410bd347204bfa981a5980220f7c8242a756e 100644 (file)
--- a/doc/doc-docbook/spec.xfpt
+++ b/doc/doc-docbook/spec.xfpt
@@ -15431,6 +15431,13 @@ are using OpenSSL, you can set &%tls_verify_certificates%& to the name of a
 directory containing certificate files. This does not work with GnuTLS; the
 option must be set to the name of a single file if you are using GnuTLS.
 
 directory containing certificate files. This does not work with GnuTLS; the
 option must be set to the name of a single file if you are using GnuTLS.
 

+These certificates should be for the certificate authorities trusted, rather
+than the public cert of individual clients.  With both OpenSSL and GnuTLS, if
+the value is a file then the certificates are sent by Exim as a server to
+connecting clients, defining the list of accepted certificate authorities.
+Thus the values defined should be considered public data.  To avoid this,
+use OpenSSL with a directory.
+

 
 .option tls_verify_hosts main "host list&!!" unset
 .cindex "TLS" "client certificate verification"
 
 .option tls_verify_hosts main "host list&!!" unset
 .cindex "TLS" "client certificate verification"