6 x509 - Certificate display and signing utility
11 [B<-inform DER|PEM|NET>]
12 [B<-outform DER|PEM|NET>]
15 [B<-CAkeyform DER|PEM>]
40 [B<-signkey filename>]
46 [B<-CAserial filename>]
49 [B<-md2|-md5|-sha1|-mdc2>]
51 [B<-extfile filename>]
52 [B<-extensions section>]
57 The B<x509> command is a multi purpose certificate utility. It can be
58 used to display certificate information, convert certificates to
59 various forms, sign certificate requests like a "mini CA" or edit
60 certificate trust settings.
62 Since there are a large number of options they will split up into
67 =head2 INPUT, OUTPUT AND GENERAL PURPOSE OPTIONS
71 =item B<-inform DER|PEM|NET>
73 This specifies the input format normally the command will expect an X509
74 certificate but this can change if other options such as B<-req> are
75 present. The DER format is the DER encoding of the certificate and PEM
76 is the base64 encoding of the DER encoding with header and footer lines
77 added. The NET option is an obscure Netscape server format that is now
80 =item B<-outform DER|PEM|NET>
82 This specifies the output format, the options have the same meaning as the
87 This specifies the input filename to read a certificate from or standard input
88 if this option is not specified.
90 =item B<-out filename>
92 This specifies the output filename to write to or standard output by
95 =item B<-md2|-md5|-sha1|-mdc2>
97 the digest to use. This affects any signing or display option that uses a message
98 digest, such as the B<-fingerprint>, B<-signkey> and B<-CA> options. If not
99 specified then MD5 is used. If the key being used to sign with is a DSA key then
100 this option has no effect: SHA1 is always used with DSA keys.
104 specifying an engine (by it's unique B<id> string) will cause B<req>
105 to attempt to obtain a functional reference to the specified engine,
106 thus initialising it if needed. The engine will then be set as the default
107 for all available algorithms.
111 =head2 DISPLAY OPTIONS
113 Note: the B<-alias> and B<-purpose> options are also display options
114 but are described in the B<TRUST SETTINGS> section.
120 prints out the certificate in text form. Full details are output including the
121 public key, signature algorithms, issuer and subject names, serial number
122 any extensions present and any trust settings.
124 =item B<-certopt option>
126 customise the output format used with B<-text>. The B<option> argument can be
127 a single option or multiple options separated by commas. The B<-certopt> switch
128 may be also be used more than once to set multiple options. See the B<TEXT OPTIONS>
129 section for more information.
133 this option prevents output of the encoded version of the request.
137 this option prints out the value of the modulus of the public key
138 contained in the certificate.
142 outputs the certificate serial number.
146 outputs the "hash" of the certificate subject name. This is used in OpenSSL to
147 form an index to allow certificates in a directory to be looked up by subject
152 outputs the subject name.
156 outputs the issuer name.
158 =item B<-nameopt option>
160 option which determines how the subject or issuer names are displayed. The
161 B<option> argument can be a single option or multiple options separated by
162 commas. Alternatively the B<-nameopt> switch may be used more than once to
163 set multiple options. See the B<NAME OPTIONS> section for more information.
167 outputs the email address(es) if any.
171 prints out the start date of the certificate, that is the notBefore date.
175 prints out the expiry date of the certificate, that is the notAfter date.
179 prints out the start and expiry dates of a certificate.
181 =item B<-fingerprint>
183 prints out the digest of the DER encoded version of the whole certificate
184 (see digest options).
188 this outputs the certificate in the form of a C source file.
192 =head2 TRUST SETTINGS
194 Please note these options are currently experimental and may well change.
196 A B<trusted certificate> is an ordinary certificate which has several
197 additional pieces of information attached to it such as the permitted
198 and prohibited uses of the certificate and an "alias".
200 Normally when a certificate is being verified at least one certificate
201 must be "trusted". By default a trusted certificate must be stored
202 locally and must be a root CA: any certificate chain ending in this CA
203 is then usable for any purpose.
205 Trust settings currently are only used with a root CA. They allow a finer
206 control over the purposes the root CA can be used for. For example a CA
207 may be trusted for SSL client but not SSL server use.
209 See the description of the B<verify> utility for more information on the
210 meaning of trust settings.
212 Future versions of OpenSSL will recognize trust settings on any
213 certificate: not just root CAs.
220 this causes B<x509> to output a B<trusted> certificate. An ordinary
221 or trusted certificate can be input but by default an ordinary
222 certificate is output and any trust settings are discarded. With the
223 B<-trustout> option a trusted certificate is output. A trusted
224 certificate is automatically output if any trust settings are modified.
226 =item B<-setalias arg>
228 sets the alias of the certificate. This will allow the certificate
229 to be referred to using a nickname for example "Steve's Certificate".
233 outputs the certificate alias, if any.
237 clears all the permitted or trusted uses of the certificate.
241 clears all the prohibited or rejected uses of the certificate.
243 =item B<-addtrust arg>
245 adds a trusted certificate use. Any object name can be used here
246 but currently only B<clientAuth> (SSL client use), B<serverAuth>
247 (SSL server use) and B<emailProtection> (S/MIME email) are used.
248 Other OpenSSL applications may define additional uses.
250 =item B<-addreject arg>
252 adds a prohibited use. It accepts the same values as the B<-addtrust>
257 this option performs tests on the certificate extensions and outputs
258 the results. For a more complete description see the B<CERTIFICATE
263 =head2 SIGNING OPTIONS
265 The B<x509> utility can be used to sign certificates and requests: it
266 can thus behave like a "mini CA".
270 =item B<-signkey filename>
272 this option causes the input file to be self signed using the supplied
275 If the input file is a certificate it sets the issuer name to the
276 subject name (i.e. makes it self signed) changes the public key to the
277 supplied value and changes the start and end dates. The start date is
278 set to the current time and the end date is set to a value determined
279 by the B<-days> option. Any certificate extensions are retained unless
280 the B<-clrext> option is supplied.
282 If the input is a certificate request then a self signed certificate
283 is created using the supplied private key using the subject name in
288 delete any extensions from a certificate. This option is used when a
289 certificate is being created from another certificate (for example with
290 the B<-signkey> or the B<-CA> options). Normally all extensions are
293 =item B<-keyform PEM|DER>
295 specifies the format (DER or PEM) of the private key file used in the
300 specifies the number of days to make a certificate valid for. The default
305 converts a certificate into a certificate request. The B<-signkey> option
306 is used to pass the required private key.
310 by default a certificate is expected on input. With this option a
311 certificate request is expected instead.
313 =item B<-set_serial n>
315 specifies the serial number to use. This option can be used with either
316 the B<-signkey> or B<-CA> options. If used in conjunction with the B<-CA>
317 option the serial number file (as specified by the B<-CAserial> or
318 B<-CAcreateserial> options) is not used.
320 The serial number can be decimal or hex (if preceded by B<0x>). Negative
321 serial numbers can also be specified but their use is not recommended.
323 =item B<-CA filename>
325 specifies the CA certificate to be used for signing. When this option is
326 present B<x509> behaves like a "mini CA". The input file is signed by this
327 CA using this option: that is its issuer name is set to the subject name
328 of the CA and it is digitally signed using the CAs private key.
330 This option is normally combined with the B<-req> option. Without the
331 B<-req> option the input is a certificate which must be self signed.
333 =item B<-CAkey filename>
335 sets the CA private key to sign a certificate with. If this option is
336 not specified then it is assumed that the CA private key is present in
337 the CA certificate file.
339 =item B<-CAserial filename>
341 sets the CA serial number file to use.
343 When the B<-CA> option is used to sign a certificate it uses a serial
344 number specified in a file. This file consist of one line containing
345 an even number of hex digits with the serial number to use. After each
346 use the serial number is incremented and written out to the file again.
348 The default filename consists of the CA certificate file base name with
349 ".srl" appended. For example if the CA certificate file is called
350 "mycacert.pem" it expects to find a serial number file called "mycacert.srl".
352 =item B<-CAcreateserial>
354 with this option the CA serial number file is created if it does not exist:
355 it will contain the serial number "02" and the certificate being signed will
356 have the 1 as its serial number. Normally if the B<-CA> option is specified
357 and the serial number file does not exist it is an error.
359 =item B<-extfile filename>
361 file containing certificate extensions to use. If not specified then
362 no extensions are added to the certificate.
364 =item B<-extensions section>
366 the section to add certificate extensions from. If this option is not
367 specified then the extensions should either be contained in the unnamed
368 (default) section or the default section should contain a variable called
369 "extensions" which contains the section to use.
375 The B<nameopt> command line switch determines how the subject and issuer
376 names are displayed. If no B<nameopt> switch is present the default "oneline"
377 format is used which is compatible with previous versions of OpenSSL.
378 Each option is described in detail below, all options can be preceded by
379 a B<-> to turn the option off. Only the first four will normally be used.
385 use the old format. This is equivalent to specifying no name options at all.
389 displays names compatible with RFC2253 equivalent to B<esc_2253>, B<esc_ctrl>,
390 B<esc_msb>, B<utf8>, B<dump_nostr>, B<dump_unknown>, B<dump_der>,
391 B<sep_comma_plus>, B<dn_rev> and B<sname>.
395 a oneline format which is more readable than RFC2253. It is equivalent to
396 specifying the B<esc_2253>, B<esc_ctrl>, B<esc_msb>, B<utf8>, B<dump_nostr>,
397 B<dump_der>, B<use_quote>, B<sep_comma_plus_spc>, B<spc_eq> and B<sname>
402 a multiline format. It is equivalent B<esc_ctrl>, B<esc_msb>, B<sep_multiline>,
403 B<spc_eq>, B<lname> and B<align>.
407 escape the "special" characters required by RFC2253 in a field That is
408 B<,+"E<lt>E<gt>;>. Additionally B<#> is escaped at the beginning of a string
409 and a space character at the beginning or end of a string.
413 escape control characters. That is those with ASCII values less than
414 0x20 (space) and the delete (0x7f) character. They are escaped using the
415 RFC2253 \XX notation (where XX are two hex digits representing the
420 escape characters with the MSB set, that is with ASCII values larger than
425 escapes some characters by surrounding the whole string with B<"> characters,
426 without the option all escaping is done with the B<\> character.
430 convert all strings to UTF8 format first. This is required by RFC2253. If
431 you are lucky enough to have a UTF8 compatible terminal then the use
432 of this option (and B<not> setting B<esc_msb>) may result in the correct
433 display of multibyte (international) characters. Is this option is not
434 present then multibyte characters larger than 0xff will be represented
435 using the format \UXXXX for 16 bits and \WXXXXXXXX for 32 bits.
436 Also if this option is off any UTF8Strings will be converted to their
437 character form first.
441 this option does not attempt to interpret multibyte characters in any
442 way. That is their content octets are merely dumped as though one octet
443 represents each character. This is useful for diagnostic purposes but
444 will result in rather odd looking output.
448 show the type of the ASN1 character string. The type precedes the
449 field contents. For example "BMPSTRING: Hello World".
453 when this option is set any fields that need to be hexdumped will
454 be dumped using the DER encoding of the field. Otherwise just the
455 content octets will be displayed. Both options use the RFC2253
460 dump non character string types (for example OCTET STRING) if this
461 option is not set then non character string types will be displayed
462 as though each content octet represents a single character.
466 dump all fields. This option when used with B<dump_der> allows the
467 DER encoding of the structure to be unambiguously determined.
469 =item B<dump_unknown>
471 dump any field whose OID is not recognised by OpenSSL.
473 =item B<sep_comma_plus>, B<sep_comma_plus_space>, B<sep_semi_plus_space>,
476 these options determine the field separators. The first character is
477 between RDNs and the second between multiple AVAs (multiple AVAs are
478 very rare and their use is discouraged). The options ending in
479 "space" additionally place a space after the separator to make it
480 more readable. The B<sep_multiline> uses a linefeed character for
481 the RDN separator and a spaced B<+> for the AVA separator. It also
482 indents the fields by four characters.
486 reverse the fields of the DN. This is required by RFC2253. As a side
487 effect this also reverses the order of multiple AVAs but this is
490 =item B<nofname>, B<sname>, B<lname>, B<oid>
492 these options alter how the field name is displayed. B<nofname> does
493 not display the field at all. B<sname> uses the "short name" form
494 (CN for commonName for example). B<lname> uses the long form.
495 B<oid> represents the OID in numerical form and is useful for
500 align field values for a more readable output. Only usable with
505 places spaces round the B<=> character which follows the field
512 As well as customising the name output format, it is also possible to
513 customise the actual fields printed using the B<certopt> options when
514 the B<text> option is present. The default behaviour is to print all fields.
520 use the old format. This is equivalent to specifying no output options at all.
524 don't print header information: that is the lines saying "Certificate" and "Data".
528 don't print out the version number.
532 don't print out the serial number.
536 don't print out the signature algorithm used.
540 don't print the validity, that is the B<notBefore> and B<notAfter> fields.
544 don't print out the subject name.
548 don't print out the issuer name.
552 don't print out the public key.
556 don't give a hexadecimal dump of the certificate signature.
560 don't print out certificate trust information.
562 =item B<no_extensions>
564 don't print out any X509V3 extensions.
568 retain default extension behaviour: attempt to print out unsupported certificate extensions.
572 print an error message for unsupported certificate extensions.
576 ASN1 parse unsupported extensions.
580 hex dump unsupported extensions.
584 the value used by the B<ca> utility, equivalent to B<no_issuer>, B<no_pubkey>, B<no_header>,
585 B<no_version>, B<no_sigdump> and B<no_signame>.
591 Note: in these examples the '\' means the example should be all on one
594 Display the contents of a certificate:
596 openssl x509 -in cert.pem -noout -text
598 Display the certificate serial number:
600 openssl x509 -in cert.pem -noout -serial
602 Display the certificate subject name:
604 openssl x509 -in cert.pem -noout -subject
606 Display the certificate subject name in RFC2253 form:
608 openssl x509 -in cert.pem -noout -subject -nameopt RFC2253
610 Display the certificate subject name in oneline form on a terminal
613 openssl x509 -in cert.pem -noout -subject -nameopt oneline,-escmsb
615 Display the certificate MD5 fingerprint:
617 openssl x509 -in cert.pem -noout -fingerprint
619 Display the certificate SHA1 fingerprint:
621 openssl x509 -sha1 -in cert.pem -noout -fingerprint
623 Convert a certificate from PEM to DER format:
625 openssl x509 -in cert.pem -inform PEM -out cert.der -outform DER
627 Convert a certificate to a certificate request:
629 openssl x509 -x509toreq -in cert.pem -out req.pem -signkey key.pem
631 Convert a certificate request into a self signed certificate using
634 openssl x509 -req -in careq.pem -extfile openssl.cnf -extensions v3_ca \
635 -signkey key.pem -out cacert.pem
637 Sign a certificate request using the CA certificate above and add user
638 certificate extensions:
640 openssl x509 -req -in req.pem -extfile openssl.cnf -extensions v3_usr \
641 -CA cacert.pem -CAkey key.pem -CAcreateserial
644 Set a certificate to be trusted for SSL client use and change set its alias to
647 openssl x509 -in cert.pem -addtrust clientAuth \
648 -setalias "Steve's Class 1 CA" -out trust.pem
652 The PEM format uses the header and footer lines:
654 -----BEGIN CERTIFICATE-----
655 -----END CERTIFICATE-----
657 it will also handle files containing:
659 -----BEGIN X509 CERTIFICATE-----
660 -----END X509 CERTIFICATE-----
662 Trusted certificates have the lines
664 -----BEGIN TRUSTED CERTIFICATE-----
665 -----END TRUSTED CERTIFICATE-----
667 The conversion to UTF8 format used with the name options assumes that
668 T61Strings use the ISO8859-1 character set. This is wrong but Netscape
669 and MSIE do this as do many certificates. So although this is incorrect
670 it is more likely to display the majority of certificates correctly.
672 The B<-fingerprint> option takes the digest of the DER encoded certificate.
673 This is commonly called a "fingerprint". Because of the nature of message
674 digests the fingerprint of a certificate is unique to that certificate and
675 two certificates with the same fingerprint can be considered to be the same.
677 The Netscape fingerprint uses MD5 whereas MSIE uses SHA1.
679 The B<-email> option searches the subject name and the subject alternative
680 name extension. Only unique email addresses will be printed out: it will
681 not print the same address more than once.
683 =head1 CERTIFICATE EXTENSIONS
685 The B<-purpose> option checks the certificate extensions and determines
686 what the certificate can be used for. The actual checks done are rather
687 complex and include various hacks and workarounds to handle broken
688 certificates and software.
690 The same code is used when verifying untrusted certificates in chains
691 so this section is useful if a chain is rejected by the verify code.
693 The basicConstraints extension CA flag is used to determine whether the
694 certificate can be used as a CA. If the CA flag is true then it is a CA,
695 if the CA flag is false then it is not a CA. B<All> CAs should have the
698 If the basicConstraints extension is absent then the certificate is
699 considered to be a "possible CA" other extensions are checked according
700 to the intended use of the certificate. A warning is given in this case
701 because the certificate should really not be regarded as a CA: however
702 it is allowed to be a CA to work around some broken software.
704 If the certificate is a V1 certificate (and thus has no extensions) and
705 it is self signed it is also assumed to be a CA but a warning is again
706 given: this is to work around the problem of Verisign roots which are V1
707 self signed certificates.
709 If the keyUsage extension is present then additional restraints are
710 made on the uses of the certificate. A CA certificate B<must> have the
711 keyCertSign bit set if the keyUsage extension is present.
713 The extended key usage extension places additional restrictions on the
714 certificate uses. If this extension is present (whether critical or not)
715 the key can only be used for the purposes specified.
717 A complete description of each test is given below. The comments about
718 basicConstraints and keyUsage and V1 certificates above apply to B<all>
726 The extended key usage extension must be absent or include the "web client
727 authentication" OID. keyUsage must be absent or it must have the
728 digitalSignature bit set. Netscape certificate type must be absent or it must
729 have the SSL client bit set.
731 =item B<SSL Client CA>
733 The extended key usage extension must be absent or include the "web client
734 authentication" OID. Netscape certificate type must be absent or it must have
735 the SSL CA bit set: this is used as a work around if the basicConstraints
740 The extended key usage extension must be absent or include the "web server
741 authentication" and/or one of the SGC OIDs. keyUsage must be absent or it
742 must have the digitalSignature, the keyEncipherment set or both bits set.
743 Netscape certificate type must be absent or have the SSL server bit set.
745 =item B<SSL Server CA>
747 The extended key usage extension must be absent or include the "web server
748 authentication" and/or one of the SGC OIDs. Netscape certificate type must
749 be absent or the SSL CA bit must be set: this is used as a work around if the
750 basicConstraints extension is absent.
752 =item B<Netscape SSL Server>
754 For Netscape SSL clients to connect to an SSL server it must have the
755 keyEncipherment bit set if the keyUsage extension is present. This isn't
756 always valid because some cipher suites use the key for digital signing.
757 Otherwise it is the same as a normal SSL server.
759 =item B<Common S/MIME Client Tests>
761 The extended key usage extension must be absent or include the "email
762 protection" OID. Netscape certificate type must be absent or should have the
763 S/MIME bit set. If the S/MIME bit is not set in netscape certificate type
764 then the SSL client bit is tolerated as an alternative but a warning is shown:
765 this is because some Verisign certificates don't set the S/MIME bit.
767 =item B<S/MIME Signing>
769 In addition to the common S/MIME client tests the digitalSignature bit must
770 be set if the keyUsage extension is present.
772 =item B<S/MIME Encryption>
774 In addition to the common S/MIME tests the keyEncipherment bit must be set
775 if the keyUsage extension is present.
779 The extended key usage extension must be absent or include the "email
780 protection" OID. Netscape certificate type must be absent or must have the
781 S/MIME CA bit set: this is used as a work around if the basicConstraints
786 The keyUsage extension must be absent or it must have the CRL signing bit
789 =item B<CRL Signing CA>
791 The normal CA tests apply. Except in this case the basicConstraints extension
798 Extensions in certificates are not transferred to certificate requests and
801 It is possible to produce invalid certificates or requests by specifying the
802 wrong private key or using inconsistent options in some cases: these should
805 There should be options to explicitly set such things as start and end
806 dates rather than an offset from the current time.
808 The code to implement the verify behaviour described in the B<TRUST SETTINGS>
809 is currently being developed. It thus describes the intended behaviour rather
810 than the current behaviour. It is hoped that it will represent reality in
811 OpenSSL 0.9.5 and later.
815 L<req(1)|req(1)>, L<ca(1)|ca(1)>, L<genrsa(1)|genrsa(1)>,
816 L<gendsa(1)|gendsa(1)>, L<verify(1)|verify(1)>