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clarify documentation

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This commit is contained in:
Dr. Stephen Henson 2010-02-18 12:41:33 +00:00
parent 7512141162
commit 69582a592e
1 changed files with 25 additions and 13 deletions
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38
doc/ssl/SSL_CTX_set_options.pod
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@ -224,10 +224,16 @@ of RFC4507bis tickets for stateless session resumption.
If this option is set this functionality is disabled and tickets will
not be used by clients or servers.
=item SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION, SSL_OP_LEGACY_SERVER_CONNECT
=item SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
See the B<SECURE RENEGOTIATION> section for a discussion of the purpose of
these options.
Allow legacy insecure renegotiation between OpenSSL and unpatched clients or
servers. See the B<SECURE RENEGOTIATION> section for more details.
=item SSL_OP_LEGACY_SERVER_CONNECT
Allow legacy insecure renegotiation between OpenSSL and unpatched servers
B<only>: this option is currently set by default. See the
B<SECURE RENEGOTIATION> section for more details.
=back
@ -275,15 +281,18 @@ was refused.
=head2 Patched OpenSSL client and unpatched server.
If the option B<SSL_OP_LEGACY_SERVER_CONNECT> is set then initial connections
If the option B<SSL_OP_LEGACY_SERVER_CONNECT> or
B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION> is set then initial connections
and renegotiation between patched OpenSSL clients and unpatched servers
succeeds.
succeeds. If neither option is set then initial connections to unpatched
servers will fail.
This option is currently set by default even though it has security
implications: otherwise it would be impossible to connect to unpatched servers
(i.e. all of them initially) and this is clearly not acceptable. Renegotiation
is permitted because this does not add any additional security issues: during
an attack clients do not see any renegotiations anyway.
The option B<SSL_OP_LEGACY_SERVER_CONNECT> is currently set by default even
though it has security implications: otherwise it would be impossible to
connect to unpatched servers (i.e. all of them initially) and this is clearly
not acceptable. Renegotiation is permitted because this does not add any
additional security issues: during an attack clients do not see any
renegotiations anyway.
As more servers become patched the option B<SSL_OP_LEGACY_SERVER_CONNECT> will
B<not> be set by default in a future version of OpenSSL.
@ -296,9 +305,12 @@ unpatched servers (and thus avoid any security issues) should always B<clear>
B<SSL_OP_LEGACY_SERVER_CONNECT> using SSL_CTX_clear_options() or
SSL_clear_options().
As in the previous case if the option
B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION> is set then renegotiation
B<always> succeeds.
The difference between the B<SSL_OP_LEGACY_SERVER_CONNECT> and
B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION> options is that
B<SSL_OP_LEGACY_SERVER_CONNECT> enables initial connections and secure
renegotiation between OpenSSL clients and unpatched servers B<only>, while
B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION> allows initial connections
and renegotiation between OpenSSL and unpatched clients or servers.
=head1 RETURN VALUES