diff options
Diffstat (limited to 'doc/doc-txt')
| -rw-r--r-- | doc/doc-txt/NewStuff | 3 | ||||
| -rw-r--r-- | doc/doc-txt/OptionLists.txt | 2 | ||||
| -rw-r--r-- | doc/doc-txt/experimental-spec.txt | 59 |
3 files changed, 5 insertions, 59 deletions
diff --git a/doc/doc-txt/NewStuff b/doc/doc-txt/NewStuff index 53d7b5c9a..f3bf3e8e5 100644 --- a/doc/doc-txt/NewStuff +++ b/doc/doc-txt/NewStuff @@ -15,6 +15,9 @@ Version 4.95 2. The native SRS support, previously experimental, is now supported. It is not built unless specified in the Local/Makefile. + 3. TLS resumption support, previously experimental, is now supported and + included in default builds. + Version 4.94 ------------ diff --git a/doc/doc-txt/OptionLists.txt b/doc/doc-txt/OptionLists.txt index f15ccd553..39827b6ee 100644 --- a/doc/doc-txt/OptionLists.txt +++ b/doc/doc-txt/OptionLists.txt @@ -602,6 +602,8 @@ tls_privatekey string* unset main tls_remember_emstp boolean false main 4.21 tls_require_ciphers string* unset smtp 4.00 replaces tls_verify_ciphers string* unset main 4.33 +tls_resumption_hosts host list* unset main 4.95 + host list* unset smtp 4.95 tls_sni string* unset main 4.80 tls_tempfail_tryclear boolean true smtp 4.05 tls_try_verify_hosts host list unset main 4.00 diff --git a/doc/doc-txt/experimental-spec.txt b/doc/doc-txt/experimental-spec.txt index 2b6d01f33..599d2bb1b 100644 --- a/doc/doc-txt/experimental-spec.txt +++ b/doc/doc-txt/experimental-spec.txt @@ -684,65 +684,6 @@ used via the transport in question. - -TLS Session Resumption ----------------------- -TLS Session Resumption for TLS 1.2 and TLS 1.3 connections can be used (defined -in RFC 5077 for 1.2). The support for this can be included by building with -EXPERIMENTAL_TLS_RESUME defined. This requires GnuTLS 3.6.3 or OpenSSL 1.1.1 -(or later). - -Session resumption (this is the "stateless" variant) involves the server sending -a "session ticket" to the client on one connection, which can be stored by the -client and used for a later session. The ticket contains sufficient state for -the server to reconstruct the TLS session, avoiding some expensive crypto -calculation and one full packet roundtrip time. - -Operational cost/benefit: - The extra data being transmitted costs a minor amount, and the client has - extra costs in storing and retrieving the data. - - In the Exim/Gnutls implementation the extra cost on an initial connection - which is TLS1.2 over a loopback path is about 6ms on 2017-laptop class hardware. - The saved cost on a subsequent connection is about 4ms; three or more - connections become a net win. On longer network paths, two or more - connections will have an average lower startup time thanks to the one - saved packet roundtrip. TLS1.3 will save the crypto cpu costs but not any - packet roundtrips. - - Since a new hints DB is used, the hints DB maintenance should be updated - to additionally handle "tls". - -Security aspects: - The session ticket is encrypted, but is obviously an additional security - vulnarability surface. An attacker able to decrypt it would have access - all connections using the resumed session. - The session ticket encryption key is not committed to storage by the server - and is rotated regularly (OpenSSL: 1hr, and one previous key is used for - overlap; GnuTLS 6hr but does not specify any overlap). - Tickets have limited lifetime (2hr, and new ones issued after 1hr under - OpenSSL. GnuTLS 2hr, appears to not do overlap). - - There is a question-mark over the security of the Diffie-Helman parameters - used for session negotiation. TBD. q-value; cf bug 1895 - -Observability: - New log_selector "tls_resumption", appends an asterisk to the tls_cipher "X=" - element. - - Variables $tls_{in,out}_resumption have bits 0-4 indicating respectively - support built, client requested ticket, client offered session, - server issued ticket, resume used. A suitable decode list is provided - in the builtin macro _RESUME_DECODE for ${listextract {}{}}. - -Issues: - In a resumed session: - $tls_{in,out}_cipher will have values different to the original (under GnuTLS) - $tls_{in,out}_ocsp will be "not requested" or "no response", and - hosts_require_ocsp will fail - - - Dovecot authenticator via inet socket ------------------------------------ If Dovecot is configured similar to :- |