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authorJeremy Harris <jgh146exb@wizmail.org>2018-06-20 20:28:54 +0100
committerJeremy Harris <jgh146exb@wizmail.org>2018-06-20 20:57:02 +0100
commit0c3807a8165cbc982f330831a429571f2ff7beec (patch)
tree9e94cf56b9238336d99385b196090df791dee100 /doc
parent7a8b95190c22a8176c583985a41beb3e9ae831cd (diff)
OpenSSL: TLSv1.3 notes
Diffstat (limited to 'doc')
-rw-r--r--doc/doc-docbook/spec.xfpt17
1 files changed, 16 insertions, 1 deletions
diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt
index 7ae09cfbe..daaf0032c 100644
--- a/doc/doc-docbook/spec.xfpt
+++ b/doc/doc-docbook/spec.xfpt
@@ -27417,7 +27417,10 @@ the size of the generated prime, so it might still be too large.
.oindex "&%tls_require_ciphers%&" "OpenSSL"
There is a function in the OpenSSL library that can be passed a list of cipher
suites before the cipher negotiation takes place. This specifies which ciphers
-are acceptable. The list is colon separated and may contain names like
+.new
+are acceptable for TLS versions prior to 1.3.
+.wen
+The list is colon separated and may contain names like
DES-CBC3-SHA. Exim passes the expanded value of &%tls_require_ciphers%&
directly to this function call.
Many systems will install the OpenSSL manual-pages, so you may have
@@ -27482,6 +27485,18 @@ This example will prefer ECDSA-authenticated ciphers over RSA ones:
tls_require_ciphers = ECDSA:RSA:!COMPLEMENTOFDEFAULT
.endd
+.new
+For TLS version 1.3 the control available is less fine-grained
+and Exim does not provide access to it at present.
+The value of the &%tls_require_ciphers%& option is ignored when
+TLS version 1.3 is negociated.
+
+As of writing the library default cipher suite list for TLSv1.3 is
+.code
+TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256
+.endd
+.wen
+
.section "Requiring specific ciphers or other parameters in GnuTLS" &&&
"SECTreqciphgnu"