NetBSD/lib/libcrypto/man/SSL_CTX_set_options.3

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.\" $NetBSD: SSL_CTX_set_options.3,v 1.2 2002/02/07 07:00:41 ross Exp $
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.\" ======================================================================
.\"
.IX Title "SSL_CTX_set_options 3"
.TH SSL_CTX_set_options 3 "0.9.6a" "2001-04-12" "OpenSSL"
.UC
.SH "NAME"
SSL_CTX_set_options, SSL_set_options, SSL_CTX_get_options, SSL_get_options \- manipulate \s-1SSL\s0 engine options
.SH "LIBRARY"
libcrypto, -lcrypto
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include \*[Lt]openssl/ssl.h\*[Gt]
.Ve
.Vb 2
\& long SSL_CTX_set_options(SSL_CTX *ctx, long options);
\& long SSL_set_options(SSL *ssl, long options);
.Ve
.Vb 2
\& long SSL_CTX_get_options(SSL_CTX *ctx);
\& long SSL_get_options(SSL *ssl);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
\&\fISSL_CTX_set_options()\fR adds the options set via bitmask in \fBoptions\fR to \fBctx\fR.
Options already set before are not cleared.
.PP
\&\fISSL_set_options()\fR adds the options set via bitmask in \fBoptions\fR to \fBssl\fR.
Options already set before are not cleared.
.PP
\&\fISSL_CTX_get_options()\fR returns the options set for \fBctx\fR.
.PP
\&\fISSL_get_options()\fR returns the options set for \fBssl\fR.
.SH "NOTES"
.IX Header "NOTES"
The behaviour of the \s-1SSL\s0 library can be changed by setting several options.
The options are coded as bitmasks and can be combined by a logical \fBor\fR
operation (|). Options can only be added but can never be reset.
.PP
During a handshake, the option settings of the \s-1SSL\s0 object used. When
a new \s-1SSL\s0 object is created from a context using \fISSL_new()\fR, the current
option setting is copied. Changes to \fBctx\fR do not affect already created
\&\s-1SSL\s0 objects. \fISSL_clear()\fR does not affect the settings.
.PP
The following \fBbug workaround\fR options are available:
.Ip "\s-1SSL_OP_MICROSOFT_SESS_ID_BUG\s0" 4
.IX Item "SSL_OP_MICROSOFT_SESS_ID_BUG"
www.microsoft.com \- when talking SSLv2, if session-id reuse is
performed, the session-id passed back in the server-finished message
is different from the one decided upon.
.Ip "\s-1SSL_OP_NETSCAPE_CHALLENGE_BUG\s0" 4
.IX Item "SSL_OP_NETSCAPE_CHALLENGE_BUG"
Netscape-Commerce/1.12, when talking SSLv2, accepts a 32 byte
challenge but then appears to only use 16 bytes when generating the
encryption keys. Using 16 bytes is ok but it should be ok to use 32.
According to the SSLv3 spec, one should use 32 bytes for the challenge
when operating in SSLv2/v3 compatibility mode, but as mentioned above,
this breaks this server so 16 bytes is the way to go.
.Ip "\s-1SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG\s0" 4
.IX Item "SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG"
ssl3.netscape.com:443, first a connection is established with \s-1RC4\-MD5\s0.
If it is then resumed, we end up using \s-1DES-CBC3\-SHA\s0. It should be
\&\s-1RC4\-MD5\s0 according to 7.6.1.3, 'cipher_suite'.
.Sp
Netscape-Enterprise/2.01 (https://merchant.netscape.com) has this bug.
It only really shows up when connecting via SSLv2/v3 then reconnecting
via SSLv3. The cipher list changes....
.Sp
\&\s-1NEW\s0 \s-1INFORMATION\s0. Try connecting with a cipher list of just
\&\s-1DES-CBC-SHA:RC4\-MD5\s0. For some weird reason, each new connection uses
\&\s-1RC4\-MD5\s0, but a re-connect tries to use \s-1DES-CBC-SHA\s0. So netscape, when
doing a re-connect, always takes the first cipher in the cipher list.
.Ip "\s-1SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG\s0" 4
.IX Item "SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG"
\&...
.Ip "\s-1SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER\s0" 4
.IX Item "SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER"
\&...
.Ip "\s-1SSL_OP_MSIE_SSLV2_RSA_PADDING\s0" 4
.IX Item "SSL_OP_MSIE_SSLV2_RSA_PADDING"
\&...
.Ip "\s-1SSL_OP_SSLEAY_080_CLIENT_DH_BUG\s0" 4
.IX Item "SSL_OP_SSLEAY_080_CLIENT_DH_BUG"
\&...
.Ip "\s-1SSL_OP_TLS_D5_BUG\s0" 4
.IX Item "SSL_OP_TLS_D5_BUG"
\&...
.Ip "\s-1SSL_OP_TLS_BLOCK_PADDING_BUG\s0" 4
.IX Item "SSL_OP_TLS_BLOCK_PADDING_BUG"
\&...
.Ip "\s-1SSL_OP_TLS_ROLLBACK_BUG\s0" 4
.IX Item "SSL_OP_TLS_ROLLBACK_BUG"
Disable version rollback attack detection.
.Sp
During the client key exchange, the client must send the same information
about acceptable \s-1SSL/TLS\s0 protocol levels as during the first hello. Some
clients violate this rule by adapting to the server's answer. (Example:
the client sends a SSLv2 hello and accepts up to SSLv3.1=TLSv1, the server
only understands up to SSLv3. In this case the client must still use the
same SSLv3.1=TLSv1 announcement. Some clients step down to SSLv3 with respect
to the server's answer and violate the version rollback protection.)
.Ip "\s-1SSL_OP_ALL\s0" 4
.IX Item "SSL_OP_ALL"
All of the above bug workarounds.
.PP
It is save and recommended to use \s-1SSL_OP_ALL\s0 to enable the bug workaround
options.
.PP
The following \fBmodifying\fR options are available:
.Ip "\s-1SSL_OP_SINGLE_DH_USE\s0" 4
.IX Item "SSL_OP_SINGLE_DH_USE"
Always create a new key when using temporary \s-1DH\s0 parameters.
.Ip "\s-1SSL_OP_EPHEMERAL_RSA\s0" 4
.IX Item "SSL_OP_EPHEMERAL_RSA"
Also use the temporary \s-1RSA\s0 key when doing \s-1RSA\s0 operations.
.Ip "\s-1SSL_OP_PKCS1_CHECK_1\s0" 4
.IX Item "SSL_OP_PKCS1_CHECK_1"
\&...
.Ip "\s-1SSL_OP_PKCS1_CHECK_2\s0" 4
.IX Item "SSL_OP_PKCS1_CHECK_2"
\&...
.Ip "\s-1SSL_OP_NETSCAPE_CA_DN_BUG\s0" 4
.IX Item "SSL_OP_NETSCAPE_CA_DN_BUG"
If we accept a netscape connection, demand a client cert, have a
non-self-sighed \s-1CA\s0 which does not have it's \s-1CA\s0 in netscape, and the
browser has a cert, it will crash/hang. Works for 3.x and 4.xbeta
.Ip "\s-1SSL_OP_NON_EXPORT_FIRST\s0" 4
.IX Item "SSL_OP_NON_EXPORT_FIRST"
On servers try to use non-export (stronger) ciphers first. This option does
not work under all circumstances (in the code it is declared \*(L"broken\*(R").
.Ip "\s-1SSL_OP_NETSCAPE_DEMO_CIPHER_CHANGE_BUG\s0" 4
.IX Item "SSL_OP_NETSCAPE_DEMO_CIPHER_CHANGE_BUG"
\&...
.Ip "SSL_OP_NO_SSLv2" 4
.IX Item "SSL_OP_NO_SSLv2"
Do not use the SSLv2 protocol.
.Ip "SSL_OP_NO_SSLv3" 4
.IX Item "SSL_OP_NO_SSLv3"
Do not use the SSLv3 protocol.
.Ip "SSL_OP_NO_TLSv1" 4
.IX Item "SSL_OP_NO_TLSv1"
Do not use the TLSv1 protocol.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\fISSL_CTX_set_options()\fR and \fISSL_set_options()\fR return the new options bitmask
after adding \fBoptions\fR.
.PP
\&\fISSL_CTX_get_options()\fR and \fISSL_get_options()\fR return the current bitmask.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
ssl(3), SSL_new(3), SSL_clear(3)
.SH "HISTORY"
.IX Header "HISTORY"
\&\s-1SSL_OP_TLS_ROLLBACK_BUG\s0 has been added in OpenSSL 0.9.6.