New option SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS for disabling CBC

[openssl.git] / doc / ssl / SSL_CTX_set_options.pod

diff --git a/doc/ssl/SSL_CTX_set_options.pod b/doc/ssl/SSL_CTX_set_options.pod
index 1498bd4f1e45a885b341e4c89e94107d1c855984..3b918178fd4125f4e8479dd6d3a9c6f7385cc26f 100644 (file)
--- a/doc/ssl/SSL_CTX_set_options.pod
+++ b/doc/ssl/SSL_CTX_set_options.pod
@@ -100,14 +100,22 @@ doing a re-connect, always takes the first cipher in the cipher list.
 
 ...
 
+=item SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
+
+Disables a countermeasure against a SSL 3.0/TLS 1.0 protocol
+vulnerability affecting CBC ciphers, which cannot be handled by some
+broken SSL implementations.  This option has no effect for connections
+using other ciphers.
+
 =item SSL_OP_ALL
 
 All of the above bug workarounds.
 
 =back
 
-It is safe and recommended to use SSL_OP_ALL to enable the bug workaround
-options.
+It is usually safe to use B<SSL_OP_ALL> to enable the bug workaround
+options if compatibility with somewhat broken implementations is
+desired.
 
 The following B<modifying> options are available:
 
@@ -133,8 +141,8 @@ This option must be used to prevent small subgroup attacks, when
 the DH parameters were not generated using "strong" primes
 (e.g. when using DSA-parameters, see L<dhparam(1)|dhparam(1)>).
 If "strong" primes were used, it is not strictly necessary to generate
-a new DH key during each handshake but it is also recommendet.
-SSL_OP_SINGLE_DH_USE should therefore be enabled whenever
+a new DH key during each handshake but it is also recommended.
+B<SSL_OP_SINGLE_DH_USE> should therefore be enabled whenever
 temporary/ephemeral DH parameters are used.
 
 =item SSL_OP_EPHEMERAL_RSA
@@ -187,6 +195,12 @@ Do not use the SSLv3 protocol.
 
 Do not use the TLSv1 protocol.
 
+=item SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
+
+When performing renegotiation as a server, always start a new session
+(i.e., session resumption requests are only accepted in the initial
+handshake).  This option is not needed for clients.
+
 =back
 
 =head1 RETURN VALUES
@@ -205,10 +219,17 @@ L<dhparam(1)|dhparam(1)>
 
 =head1 HISTORY
 
-SSL_OP_CIPHER_SERVER_PREFERENCE has been added in OpenSSL 0.9.7.
+B<SSL_OP_CIPHER_SERVER_PREFERENCE> and
+B<SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION> have been added in
+OpenSSL 0.9.7.
+
+B<SSL_OP_TLS_ROLLBACK_BUG> has been added in OpenSSL 0.9.6 and was automatically
+enabled with B<SSL_OP_ALL>. As of 0.9.7, it is no longer included in B<SSL_OP_ALL>
+and must be explicitly set.
 
-SSL_OP_TLS_ROLLBACK_BUG has been added in OpenSSL 0.9.6 and was automatically
-enabled with SSL_OP_ALL. As of 0.9.7 it is no longer included in SSL_OP_ALL
-and must be explicitely set.
+B<SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS> has been added in OpenSSL 0.9.6e.
+Versions up to OpenSSL 0.9.6c do not include the countermeasure that
+can be disabled with this option (in OpenSSL 0.9.6d, it was always
+enabled).
 
 =cut