x509.pod

开源的ssl算法openssl,版本0.9.8H

B<,+"E<lt>E<gt>;>. Additionally B<#> is escaped at the beginning of a string
and a space character at the beginning or end of a string.

=item B<esc_ctrl>

escape control characters. That is those with ASCII values less than
0x20 (space) and the delete (0x7f) character. They are escaped using the
RFC2253 \XX notation (where XX are two hex digits representing the
character value).

=item B<esc_msb>

escape characters with the MSB set, that is with ASCII values larger than
127.

=item B<use_quote>

escapes some characters by surrounding the whole string with B<"> characters,
without the option all escaping is done with the B<\> character.

=item B<utf8>

convert all strings to UTF8 format first. This is required by RFC2253. If
you are lucky enough to have a UTF8 compatible terminal then the use
of this option (and B<not> setting B<esc_msb>) may result in the correct
display of multibyte (international) characters. Is this option is not
present then multibyte characters larger than 0xff will be represented
using the format \UXXXX for 16 bits and \WXXXXXXXX for 32 bits.
Also if this option is off any UTF8Strings will be converted to their
character form first.

=item B<no_type>

this option does not attempt to interpret multibyte characters in any
way. That is their content octets are merely dumped as though one octet
represents each character. This is useful for diagnostic purposes but
will result in rather odd looking output.

=item B<show_type>

show the type of the ASN1 character string. The type precedes the
field contents. For example "BMPSTRING: Hello World".

=item B<dump_der>

when this option is set any fields that need to be hexdumped will
be dumped using the DER encoding of the field. Otherwise just the
content octets will be displayed. Both options use the RFC2253
B<#XXXX...> format.

=item B<dump_nostr>

dump non character string types (for example OCTET STRING) if this
option is not set then non character string types will be displayed
as though each content octet represents a single character.

=item B<dump_all>

dump all fields. This option when used with B<dump_der> allows the
DER encoding of the structure to be unambiguously determined.

=item B<dump_unknown>

dump any field whose OID is not recognised by OpenSSL.

=item B<sep_comma_plus>, B<sep_comma_plus_space>, B<sep_semi_plus_space>,
B<sep_multiline>

these options determine the field separators. The first character is
between RDNs and the second between multiple AVAs (multiple AVAs are
very rare and their use is discouraged). The options ending in
"space" additionally place a space after the separator to make it
more readable. The B<sep_multiline> uses a linefeed character for
the RDN separator and a spaced B<+> for the AVA separator. It also
indents the fields by four characters.

=item B<dn_rev>

reverse the fields of the DN. This is required by RFC2253. As a side
effect this also reverses the order of multiple AVAs but this is
permissible.

=item B<nofname>, B<sname>, B<lname>, B<oid>

these options alter how the field name is displayed. B<nofname> does
not display the field at all. B<sname> uses the "short name" form
(CN for commonName for example). B<lname> uses the long form.
B<oid> represents the OID in numerical form and is useful for
diagnostic purpose.

=item B<align>

align field values for a more readable output. Only usable with
B<sep_multiline>.

=item B<space_eq>

places spaces round the B<=> character which follows the field
name.

=back

=head2 TEXT OPTIONS

As well as customising the name output format, it is also possible to
customise the actual fields printed using the B<certopt> options when
the B<text> option is present. The default behaviour is to print all fields.

=over 4

=item B<compatible>

use the old format. This is equivalent to specifying no output options at all.

=item B<no_header>

don't print header information: that is the lines saying "Certificate" and "Data".

=item B<no_version>

don't print out the version number.

=item B<no_serial>

don't print out the serial number.

=item B<no_signame>

don't print out the signature algorithm used.

=item B<no_validity>

don't print the validity, that is the B<notBefore> and B<notAfter> fields.

=item B<no_subject>

don't print out the subject name.

=item B<no_issuer>

don't print out the issuer name.

=item B<no_pubkey>

don't print out the public key.

=item B<no_sigdump>

don't give a hexadecimal dump of the certificate signature.

=item B<no_aux>

don't print out certificate trust information.

=item B<no_extensions>

don't print out any X509V3 extensions.

=item B<ext_default>

retain default extension behaviour: attempt to print out unsupported certificate extensions.

=item B<ext_error>

print an error message for unsupported certificate extensions.

=item B<ext_parse>

ASN1 parse unsupported extensions.

=item B<ext_dump>

hex dump unsupported extensions.

=item B<ca_default>

the value used by the B<ca> utility, equivalent to B<no_issuer>, B<no_pubkey>, B<no_header>,
B<no_version>, B<no_sigdump> and B<no_signame>.

=back

=head1 EXAMPLES

Note: in these examples the '\' means the example should be all on one
line.

Display the contents of a certificate:

 openssl x509 -in cert.pem -noout -text

Display the certificate serial number:

 openssl x509 -in cert.pem -noout -serial

Display the certificate subject name:

 openssl x509 -in cert.pem -noout -subject

Display the certificate subject name in RFC2253 form:

 openssl x509 -in cert.pem -noout -subject -nameopt RFC2253

Display the certificate subject name in oneline form on a terminal
supporting UTF8:

 openssl x509 -in cert.pem -noout -subject -nameopt oneline,-esc_msb

Display the certificate MD5 fingerprint:

 openssl x509 -in cert.pem -noout -fingerprint

Display the certificate SHA1 fingerprint:

 openssl x509 -sha1 -in cert.pem -noout -fingerprint

Convert a certificate from PEM to DER format:

 openssl x509 -in cert.pem -inform PEM -out cert.der -outform DER

Convert a certificate to a certificate request:

 openssl x509 -x509toreq -in cert.pem -out req.pem -signkey key.pem

Convert a certificate request into a self signed certificate using
extensions for a CA:

 openssl x509 -req -in careq.pem -extfile openssl.cnf -extensions v3_ca \
	-signkey key.pem -out cacert.pem

Sign a certificate request using the CA certificate above and add user
certificate extensions:

 openssl x509 -req -in req.pem -extfile openssl.cnf -extensions v3_usr \
	-CA cacert.pem -CAkey key.pem -CAcreateserial


Set a certificate to be trusted for SSL client use and change set its alias to
"Steve's Class 1 CA"

 openssl x509 -in cert.pem -addtrust clientAuth \
	-setalias "Steve's Class 1 CA" -out trust.pem

=head1 NOTES

The PEM format uses the header and footer lines:

 -----BEGIN CERTIFICATE-----
 -----END CERTIFICATE-----

it will also handle files containing:

 -----BEGIN X509 CERTIFICATE-----
 -----END X509 CERTIFICATE-----

Trusted certificates have the lines

 -----BEGIN TRUSTED CERTIFICATE-----
 -----END TRUSTED CERTIFICATE-----

The conversion to UTF8 format used with the name options assumes that
T61Strings use the ISO8859-1 character set. This is wrong but Netscape
and MSIE do this as do many certificates. So although this is incorrect
it is more likely to display the majority of certificates correctly.

The B<-fingerprint> option takes the digest of the DER encoded certificate.
This is commonly called a "fingerprint". Because of the nature of message
digests the fingerprint of a certificate is unique to that certificate and
two certificates with the same fingerprint can be considered to be the same.

The Netscape fingerprint uses MD5 whereas MSIE uses SHA1.

The B<-email> option searches the subject name and the subject alternative
name extension. Only unique email addresses will be printed out: it will
not print the same address more than once.

=head1 CERTIFICATE EXTENSIONS

The B<-purpose> option checks the certificate extensions and determines
what the certificate can be used for. The actual checks done are rather
complex and include various hacks and workarounds to handle broken
certificates and software.

The same code is used when verifying untrusted certificates in chains
so this section is useful if a chain is rejected by the verify code.

The basicConstraints extension CA flag is used to determine whether the
certificate can be used as a CA. If the CA flag is true then it is a CA,
if the CA flag is false then it is not a CA. B<All> CAs should have the
CA flag set to true.

If the basicConstraints extension is absent then the certificate is
considered to be a "possible CA" other extensions are checked according
to the intended use of the certificate. A warning is given in this case
because the certificate should really not be regarded as a CA: however
it is allowed to be a CA to work around some broken software.

If the certificate is a V1 certificate (and thus has no extensions) and
it is self signed it is also assumed to be a CA but a warning is again
given: this is to work around the problem of Verisign roots which are V1
self signed certificates.

If the keyUsage extension is present then additional restraints are
made on the uses of the certificate. A CA certificate B<must> have the
keyCertSign bit set if the keyUsage extension is present.

The extended key usage extension places additional restrictions on the
certificate uses. If this extension is present (whether critical or not)
the key can only be used for the purposes specified.

A complete description of each test is given below. The comments about
basicConstraints and keyUsage and V1 certificates above apply to B<all>
CA certificates.


=over 4

=item B<SSL Client>

The extended key usage extension must be absent or include the "web client
authentication" OID.  keyUsage must be absent or it must have the
digitalSignature bit set. Netscape certificate type must be absent or it must
have the SSL client bit set.

=item B<SSL Client CA>

The extended key usage extension must be absent or include the "web client
authentication" OID. Netscape certificate type must be absent or it must have
the SSL CA bit set: this is used as a work around if the basicConstraints
extension is absent.

=item B<SSL Server>

The extended key usage extension must be absent or include the "web server
authentication" and/or one of the SGC OIDs.  keyUsage must be absent or it
must have the digitalSignature, the keyEncipherment set or both bits set.
Netscape certificate type must be absent or have the SSL server bit set.

=item B<SSL Server CA>

The extended key usage extension must be absent or include the "web server
authentication" and/or one of the SGC OIDs.  Netscape certificate type must
be absent or the SSL CA bit must be set: this is used as a work around if the
basicConstraints extension is absent.

=item B<Netscape SSL Server>

For Netscape SSL clients to connect to an SSL server it must have the
keyEncipherment bit set if the keyUsage extension is present. This isn't
always valid because some cipher suites use the key for digital signing.
Otherwise it is the same as a normal SSL server.

=item B<Common S/MIME Client Tests>

The extended key usage extension must be absent or include the "email
protection" OID. Netscape certificate type must be absent or should have the
S/MIME bit set. If the S/MIME bit is not set in netscape certificate type
then the SSL client bit is tolerated as an alternative but a warning is shown:
this is because some Verisign certificates don't set the S/MIME bit.

=item B<S/MIME Signing>

In addition to the common S/MIME client tests the digitalSignature bit must
be set if the keyUsage extension is present.

=item B<S/MIME Encryption>

In addition to the common S/MIME tests the keyEncipherment bit must be set
if the keyUsage extension is present.

=item B<S/MIME CA>

The extended key usage extension must be absent or include the "email
protection" OID. Netscape certificate type must be absent or must have the
S/MIME CA bit set: this is used as a work around if the basicConstraints
extension is absent. 

=item B<CRL Signing>

The keyUsage extension must be absent or it must have the CRL signing bit
set.

=item B<CRL Signing CA>

The normal CA tests apply. Except in this case the basicConstraints extension
must be present.

=back

=head1 BUGS

Extensions in certificates are not transferred to certificate requests and
vice versa.

It is possible to produce invalid certificates or requests by specifying the
wrong private key or using inconsistent options in some cases: these should
be checked.

There should be options to explicitly set such things as start and end
dates rather than an offset from the current time.

The code to implement the verify behaviour described in the B<TRUST SETTINGS>
is currently being developed. It thus describes the intended behaviour rather
than the current behaviour. It is hoped that it will represent reality in
OpenSSL 0.9.5 and later.

=head1 SEE ALSO

L<req(1)|req(1)>, L<ca(1)|ca(1)>, L<genrsa(1)|genrsa(1)>,
L<gendsa(1)|gendsa(1)>, L<verify(1)|verify(1)>

=head1 HISTORY

Before OpenSSL 0.9.8, the default digest for RSA keys was MD5.

=cut