6 x509 - Certificate display and signing utility
11 [B<-inform DER|PEM|NET>]
12 [B<-outform DER|PEM|NET>]
15 [B<-CAkeyform DER|PEM>]
44 [B<-signkey filename>]
50 [B<-CAserial filename>]
51 [B<-force_pubkey key>]
54 [B<-md2|-md5|-sha1|-mdc2>]
56 [B<-extfile filename>]
57 [B<-extensions section>]
62 The B<x509> command is a multi purpose certificate utility. It can be
63 used to display certificate information, convert certificates to
64 various forms, sign certificate requests like a "mini CA" or edit
65 certificate trust settings.
67 Since there are a large number of options they will split up into
72 =head2 INPUT, OUTPUT AND GENERAL PURPOSE OPTIONS
76 =item B<-inform DER|PEM|NET>
78 This specifies the input format normally the command will expect an X509
79 certificate but this can change if other options such as B<-req> are
80 present. The DER format is the DER encoding of the certificate and PEM
81 is the base64 encoding of the DER encoding with header and footer lines
82 added. The NET option is an obscure Netscape server format that is now
85 =item B<-outform DER|PEM|NET>
87 This specifies the output format, the options have the same meaning as the
92 This specifies the input filename to read a certificate from or standard input
93 if this option is not specified.
95 =item B<-out filename>
97 This specifies the output filename to write to or standard output by
100 =item B<-md2|-md5|-sha1|-mdc2>
102 the digest to use. This affects any signing or display option that uses a message
103 digest, such as the B<-fingerprint>, B<-signkey> and B<-CA> options. If not
104 specified then SHA1 is used. If the key being used to sign with is a DSA key
105 then this option has no effect: SHA1 is always used with DSA keys.
109 specifying an engine (by its unique B<id> string) will cause B<x509>
110 to attempt to obtain a functional reference to the specified engine,
111 thus initialising it if needed. The engine will then be set as the default
112 for all available algorithms.
116 =head2 DISPLAY OPTIONS
118 Note: the B<-alias> and B<-purpose> options are also display options
119 but are described in the B<TRUST SETTINGS> section.
125 prints out the certificate in text form. Full details are output including the
126 public key, signature algorithms, issuer and subject names, serial number
127 any extensions present and any trust settings.
129 =item B<-certopt option>
131 customise the output format used with B<-text>. The B<option> argument can be
132 a single option or multiple options separated by commas. The B<-certopt> switch
133 may be also be used more than once to set multiple options. See the B<TEXT OPTIONS>
134 section for more information.
138 this option prevents output of the encoded version of the request.
142 outputs the the certificate's SubjectPublicKeyInfo block in PEM format.
146 this option prints out the value of the modulus of the public key
147 contained in the certificate.
151 outputs the certificate serial number.
153 =item B<-subject_hash>
155 outputs the "hash" of the certificate subject name. This is used in OpenSSL to
156 form an index to allow certificates in a directory to be looked up by subject
159 =item B<-issuer_hash>
161 outputs the "hash" of the certificate issuer name.
165 synonym for "-subject_hash" for backward compatibility reasons.
167 =item B<-subject_hash_old>
169 outputs the "hash" of the certificate subject name using the older algorithm
170 as used by OpenSSL versions before 1.0.0.
172 =item B<-issuer_hash_old>
174 outputs the "hash" of the certificate issuer name using the older algorithm
175 as used by OpenSSL versions before 1.0.0.
179 outputs the subject name.
183 outputs the issuer name.
185 =item B<-nameopt option>
187 option which determines how the subject or issuer names are displayed. The
188 B<option> argument can be a single option or multiple options separated by
189 commas. Alternatively the B<-nameopt> switch may be used more than once to
190 set multiple options. See the B<NAME OPTIONS> section for more information.
194 outputs the email address(es) if any.
198 outputs the OCSP responder address(es) if any.
202 prints out the start date of the certificate, that is the notBefore date.
206 prints out the expiry date of the certificate, that is the notAfter date.
210 prints out the start and expiry dates of a certificate.
212 =item B<-fingerprint>
214 prints out the digest of the DER encoded version of the whole certificate
215 (see digest options).
219 this outputs the certificate in the form of a C source file.
223 =head2 TRUST SETTINGS
225 Please note these options are currently experimental and may well change.
227 A B<trusted certificate> is an ordinary certificate which has several
228 additional pieces of information attached to it such as the permitted
229 and prohibited uses of the certificate and an "alias".
231 Normally when a certificate is being verified at least one certificate
232 must be "trusted". By default a trusted certificate must be stored
233 locally and must be a root CA: any certificate chain ending in this CA
234 is then usable for any purpose.
236 Trust settings currently are only used with a root CA. They allow a finer
237 control over the purposes the root CA can be used for. For example a CA
238 may be trusted for SSL client but not SSL server use.
240 See the description of the B<verify> utility for more information on the
241 meaning of trust settings.
243 Future versions of OpenSSL will recognize trust settings on any
244 certificate: not just root CAs.
251 this causes B<x509> to output a B<trusted> certificate. An ordinary
252 or trusted certificate can be input but by default an ordinary
253 certificate is output and any trust settings are discarded. With the
254 B<-trustout> option a trusted certificate is output. A trusted
255 certificate is automatically output if any trust settings are modified.
257 =item B<-setalias arg>
259 sets the alias of the certificate. This will allow the certificate
260 to be referred to using a nickname for example "Steve's Certificate".
264 outputs the certificate alias, if any.
268 clears all the permitted or trusted uses of the certificate.
272 clears all the prohibited or rejected uses of the certificate.
274 =item B<-addtrust arg>
276 adds a trusted certificate use. Any object name can be used here
277 but currently only B<clientAuth> (SSL client use), B<serverAuth>
278 (SSL server use) and B<emailProtection> (S/MIME email) are used.
279 Other OpenSSL applications may define additional uses.
281 =item B<-addreject arg>
283 adds a prohibited use. It accepts the same values as the B<-addtrust>
288 this option performs tests on the certificate extensions and outputs
289 the results. For a more complete description see the B<CERTIFICATE
294 =head2 SIGNING OPTIONS
296 The B<x509> utility can be used to sign certificates and requests: it
297 can thus behave like a "mini CA".
301 =item B<-signkey filename>
303 this option causes the input file to be self signed using the supplied
306 If the input file is a certificate it sets the issuer name to the
307 subject name (i.e. makes it self signed) changes the public key to the
308 supplied value and changes the start and end dates. The start date is
309 set to the current time and the end date is set to a value determined
310 by the B<-days> option. Any certificate extensions are retained unless
311 the B<-clrext> option is supplied.
313 If the input is a certificate request then a self signed certificate
314 is created using the supplied private key using the subject name in
319 delete any extensions from a certificate. This option is used when a
320 certificate is being created from another certificate (for example with
321 the B<-signkey> or the B<-CA> options). Normally all extensions are
324 =item B<-keyform PEM|DER>
326 specifies the format (DER or PEM) of the private key file used in the
331 specifies the number of days to make a certificate valid for. The default
336 converts a certificate into a certificate request. The B<-signkey> option
337 is used to pass the required private key.
341 by default a certificate is expected on input. With this option a
342 certificate request is expected instead.
344 =item B<-set_serial n>
346 specifies the serial number to use. This option can be used with either
347 the B<-signkey> or B<-CA> options. If used in conjunction with the B<-CA>
348 option the serial number file (as specified by the B<-CAserial> or
349 B<-CAcreateserial> options) is not used.
351 The serial number can be decimal or hex (if preceded by B<0x>). Negative
352 serial numbers can also be specified but their use is not recommended.
354 =item B<-CA filename>
356 specifies the CA certificate to be used for signing. When this option is
357 present B<x509> behaves like a "mini CA". The input file is signed by this
358 CA using this option: that is its issuer name is set to the subject name
359 of the CA and it is digitally signed using the CAs private key.
361 This option is normally combined with the B<-req> option. Without the
362 B<-req> option the input is a certificate which must be self signed.
364 =item B<-CAkey filename>
366 sets the CA private key to sign a certificate with. If this option is
367 not specified then it is assumed that the CA private key is present in
368 the CA certificate file.
370 =item B<-CAserial filename>
372 sets the CA serial number file to use.
374 When the B<-CA> option is used to sign a certificate it uses a serial
375 number specified in a file. This file consist of one line containing
376 an even number of hex digits with the serial number to use. After each
377 use the serial number is incremented and written out to the file again.
379 The default filename consists of the CA certificate file base name with
380 ".srl" appended. For example if the CA certificate file is called
381 "mycacert.pem" it expects to find a serial number file called "mycacert.srl".
383 =item B<-CAcreateserial>
385 with this option the CA serial number file is created if it does not exist:
386 it will contain the serial number "02" and the certificate being signed will
387 have the 1 as its serial number. Normally if the B<-CA> option is specified
388 and the serial number file does not exist it is an error.
390 =item B<-extfile filename>
392 file containing certificate extensions to use. If not specified then
393 no extensions are added to the certificate.
395 =item B<-extensions section>
397 the section to add certificate extensions from. If this option is not
398 specified then the extensions should either be contained in the unnamed
399 (default) section or the default section should contain a variable called
400 "extensions" which contains the section to use. See the
401 L<x509v3_config(5)|x509v3_config(5)> manual page for details of the
402 extension section format.
404 =item B<-force_pubkey key>
406 when a certificate is created set its public key to B<key> instead of the
407 key in the certificate or certificate request. This option is useful for
408 creating certificates where the algorithm can't normally sign requests, for
411 The format or B<key> can be specified using the B<-keyform> option.
417 The B<nameopt> command line switch determines how the subject and issuer
418 names are displayed. If no B<nameopt> switch is present the default "oneline"
419 format is used which is compatible with previous versions of OpenSSL.
420 Each option is described in detail below, all options can be preceded by
421 a B<-> to turn the option off. Only the first four will normally be used.
427 use the old format. This is equivalent to specifying no name options at all.
431 displays names compatible with RFC2253 equivalent to B<esc_2253>, B<esc_ctrl>,
432 B<esc_msb>, B<utf8>, B<dump_nostr>, B<dump_unknown>, B<dump_der>,
433 B<sep_comma_plus>, B<dn_rev> and B<sname>.
437 a oneline format which is more readable than RFC2253. It is equivalent to
438 specifying the B<esc_2253>, B<esc_ctrl>, B<esc_msb>, B<utf8>, B<dump_nostr>,
439 B<dump_der>, B<use_quote>, B<sep_comma_plus_space>, B<space_eq> and B<sname>
444 a multiline format. It is equivalent B<esc_ctrl>, B<esc_msb>, B<sep_multiline>,
445 B<space_eq>, B<lname> and B<align>.
449 escape the "special" characters required by RFC2253 in a field That is
450 B<,+"E<lt>E<gt>;>. Additionally B<#> is escaped at the beginning of a string
451 and a space character at the beginning or end of a string.
455 escape control characters. That is those with ASCII values less than
456 0x20 (space) and the delete (0x7f) character. They are escaped using the
457 RFC2253 \XX notation (where XX are two hex digits representing the
462 escape characters with the MSB set, that is with ASCII values larger than
467 escapes some characters by surrounding the whole string with B<"> characters,
468 without the option all escaping is done with the B<\> character.
472 convert all strings to UTF8 format first. This is required by RFC2253. If
473 you are lucky enough to have a UTF8 compatible terminal then the use
474 of this option (and B<not> setting B<esc_msb>) may result in the correct
475 display of multibyte (international) characters. Is this option is not
476 present then multibyte characters larger than 0xff will be represented
477 using the format \UXXXX for 16 bits and \WXXXXXXXX for 32 bits.
478 Also if this option is off any UTF8Strings will be converted to their
479 character form first.
483 this option does not attempt to interpret multibyte characters in any
484 way. That is their content octets are merely dumped as though one octet
485 represents each character. This is useful for diagnostic purposes but
486 will result in rather odd looking output.
490 show the type of the ASN1 character string. The type precedes the
491 field contents. For example "BMPSTRING: Hello World".
495 when this option is set any fields that need to be hexdumped will
496 be dumped using the DER encoding of the field. Otherwise just the
497 content octets will be displayed. Both options use the RFC2253
502 dump non character string types (for example OCTET STRING) if this
503 option is not set then non character string types will be displayed
504 as though each content octet represents a single character.
508 dump all fields. This option when used with B<dump_der> allows the
509 DER encoding of the structure to be unambiguously determined.
511 =item B<dump_unknown>
513 dump any field whose OID is not recognised by OpenSSL.
515 =item B<sep_comma_plus>, B<sep_comma_plus_space>, B<sep_semi_plus_space>,
518 these options determine the field separators. The first character is
519 between RDNs and the second between multiple AVAs (multiple AVAs are
520 very rare and their use is discouraged). The options ending in
521 "space" additionally place a space after the separator to make it
522 more readable. The B<sep_multiline> uses a linefeed character for
523 the RDN separator and a spaced B<+> for the AVA separator. It also
524 indents the fields by four characters.
528 reverse the fields of the DN. This is required by RFC2253. As a side
529 effect this also reverses the order of multiple AVAs but this is
532 =item B<nofname>, B<sname>, B<lname>, B<oid>
534 these options alter how the field name is displayed. B<nofname> does
535 not display the field at all. B<sname> uses the "short name" form
536 (CN for commonName for example). B<lname> uses the long form.
537 B<oid> represents the OID in numerical form and is useful for
542 align field values for a more readable output. Only usable with
547 places spaces round the B<=> character which follows the field
554 As well as customising the name output format, it is also possible to
555 customise the actual fields printed using the B<certopt> options when
556 the B<text> option is present. The default behaviour is to print all fields.
562 use the old format. This is equivalent to specifying no output options at all.
566 don't print header information: that is the lines saying "Certificate" and "Data".
570 don't print out the version number.
574 don't print out the serial number.
578 don't print out the signature algorithm used.
582 don't print the validity, that is the B<notBefore> and B<notAfter> fields.
586 don't print out the subject name.
590 don't print out the issuer name.
594 don't print out the public key.
598 don't give a hexadecimal dump of the certificate signature.
602 don't print out certificate trust information.
604 =item B<no_extensions>
606 don't print out any X509V3 extensions.
610 retain default extension behaviour: attempt to print out unsupported certificate extensions.
614 print an error message for unsupported certificate extensions.
618 ASN1 parse unsupported extensions.
622 hex dump unsupported extensions.
626 the value used by the B<ca> utility, equivalent to B<no_issuer>, B<no_pubkey>, B<no_header>,
627 B<no_version>, B<no_sigdump> and B<no_signame>.
633 Note: in these examples the '\' means the example should be all on one
636 Display the contents of a certificate:
638 openssl x509 -in cert.pem -noout -text
640 Display the certificate serial number:
642 openssl x509 -in cert.pem -noout -serial
644 Display the certificate subject name:
646 openssl x509 -in cert.pem -noout -subject
648 Display the certificate subject name in RFC2253 form:
650 openssl x509 -in cert.pem -noout -subject -nameopt RFC2253
652 Display the certificate subject name in oneline form on a terminal
655 openssl x509 -in cert.pem -noout -subject -nameopt oneline,-esc_msb
657 Display the certificate MD5 fingerprint:
659 openssl x509 -in cert.pem -noout -fingerprint
661 Display the certificate SHA1 fingerprint:
663 openssl x509 -sha1 -in cert.pem -noout -fingerprint
665 Convert a certificate from PEM to DER format:
667 openssl x509 -in cert.pem -inform PEM -out cert.der -outform DER
669 Convert a certificate to a certificate request:
671 openssl x509 -x509toreq -in cert.pem -out req.pem -signkey key.pem
673 Convert a certificate request into a self signed certificate using
676 openssl x509 -req -in careq.pem -extfile openssl.cnf -extensions v3_ca \
677 -signkey key.pem -out cacert.pem
679 Sign a certificate request using the CA certificate above and add user
680 certificate extensions:
682 openssl x509 -req -in req.pem -extfile openssl.cnf -extensions v3_usr \
683 -CA cacert.pem -CAkey key.pem -CAcreateserial
686 Set a certificate to be trusted for SSL client use and change set its alias to
689 openssl x509 -in cert.pem -addtrust clientAuth \
690 -setalias "Steve's Class 1 CA" -out trust.pem
694 The PEM format uses the header and footer lines:
696 -----BEGIN CERTIFICATE-----
697 -----END CERTIFICATE-----
699 it will also handle files containing:
701 -----BEGIN X509 CERTIFICATE-----
702 -----END X509 CERTIFICATE-----
704 Trusted certificates have the lines
706 -----BEGIN TRUSTED CERTIFICATE-----
707 -----END TRUSTED CERTIFICATE-----
709 The conversion to UTF8 format used with the name options assumes that
710 T61Strings use the ISO8859-1 character set. This is wrong but Netscape
711 and MSIE do this as do many certificates. So although this is incorrect
712 it is more likely to display the majority of certificates correctly.
714 The B<-fingerprint> option takes the digest of the DER encoded certificate.
715 This is commonly called a "fingerprint". Because of the nature of message
716 digests the fingerprint of a certificate is unique to that certificate and
717 two certificates with the same fingerprint can be considered to be the same.
719 The Netscape fingerprint uses MD5 whereas MSIE uses SHA1.
721 The B<-email> option searches the subject name and the subject alternative
722 name extension. Only unique email addresses will be printed out: it will
723 not print the same address more than once.
725 =head1 CERTIFICATE EXTENSIONS
727 The B<-purpose> option checks the certificate extensions and determines
728 what the certificate can be used for. The actual checks done are rather
729 complex and include various hacks and workarounds to handle broken
730 certificates and software.
732 The same code is used when verifying untrusted certificates in chains
733 so this section is useful if a chain is rejected by the verify code.
735 The basicConstraints extension CA flag is used to determine whether the
736 certificate can be used as a CA. If the CA flag is true then it is a CA,
737 if the CA flag is false then it is not a CA. B<All> CAs should have the
740 If the basicConstraints extension is absent then the certificate is
741 considered to be a "possible CA" other extensions are checked according
742 to the intended use of the certificate. A warning is given in this case
743 because the certificate should really not be regarded as a CA: however
744 it is allowed to be a CA to work around some broken software.
746 If the certificate is a V1 certificate (and thus has no extensions) and
747 it is self signed it is also assumed to be a CA but a warning is again
748 given: this is to work around the problem of Verisign roots which are V1
749 self signed certificates.
751 If the keyUsage extension is present then additional restraints are
752 made on the uses of the certificate. A CA certificate B<must> have the
753 keyCertSign bit set if the keyUsage extension is present.
755 The extended key usage extension places additional restrictions on the
756 certificate uses. If this extension is present (whether critical or not)
757 the key can only be used for the purposes specified.
759 A complete description of each test is given below. The comments about
760 basicConstraints and keyUsage and V1 certificates above apply to B<all>
768 The extended key usage extension must be absent or include the "web client
769 authentication" OID. keyUsage must be absent or it must have the
770 digitalSignature bit set. Netscape certificate type must be absent or it must
771 have the SSL client bit set.
773 =item B<SSL Client CA>
775 The extended key usage extension must be absent or include the "web client
776 authentication" OID. Netscape certificate type must be absent or it must have
777 the SSL CA bit set: this is used as a work around if the basicConstraints
782 The extended key usage extension must be absent or include the "web server
783 authentication" and/or one of the SGC OIDs. keyUsage must be absent or it
784 must have the digitalSignature, the keyEncipherment set or both bits set.
785 Netscape certificate type must be absent or have the SSL server bit set.
787 =item B<SSL Server CA>
789 The extended key usage extension must be absent or include the "web server
790 authentication" and/or one of the SGC OIDs. Netscape certificate type must
791 be absent or the SSL CA bit must be set: this is used as a work around if the
792 basicConstraints extension is absent.
794 =item B<Netscape SSL Server>
796 For Netscape SSL clients to connect to an SSL server it must have the
797 keyEncipherment bit set if the keyUsage extension is present. This isn't
798 always valid because some cipher suites use the key for digital signing.
799 Otherwise it is the same as a normal SSL server.
801 =item B<Common S/MIME Client Tests>
803 The extended key usage extension must be absent or include the "email
804 protection" OID. Netscape certificate type must be absent or should have the
805 S/MIME bit set. If the S/MIME bit is not set in netscape certificate type
806 then the SSL client bit is tolerated as an alternative but a warning is shown:
807 this is because some Verisign certificates don't set the S/MIME bit.
809 =item B<S/MIME Signing>
811 In addition to the common S/MIME client tests the digitalSignature bit must
812 be set if the keyUsage extension is present.
814 =item B<S/MIME Encryption>
816 In addition to the common S/MIME tests the keyEncipherment bit must be set
817 if the keyUsage extension is present.
821 The extended key usage extension must be absent or include the "email
822 protection" OID. Netscape certificate type must be absent or must have the
823 S/MIME CA bit set: this is used as a work around if the basicConstraints
828 The keyUsage extension must be absent or it must have the CRL signing bit
831 =item B<CRL Signing CA>
833 The normal CA tests apply. Except in this case the basicConstraints extension
840 Extensions in certificates are not transferred to certificate requests and
843 It is possible to produce invalid certificates or requests by specifying the
844 wrong private key or using inconsistent options in some cases: these should
847 There should be options to explicitly set such things as start and end
848 dates rather than an offset from the current time.
850 The code to implement the verify behaviour described in the B<TRUST SETTINGS>
851 is currently being developed. It thus describes the intended behaviour rather
852 than the current behaviour. It is hoped that it will represent reality in
853 OpenSSL 0.9.5 and later.
857 L<req(1)|req(1)>, L<ca(1)|ca(1)>, L<genrsa(1)|genrsa(1)>,
858 L<gendsa(1)|gendsa(1)>, L<verify(1)|verify(1)>,
859 L<x509v3_config(5)|x509v3_config(5)>
863 Before OpenSSL 0.9.8, the default digest for RSA keys was MD5.
865 The hash algorithm used in the B<-subject_hash> and B<-issuer_hash> options
866 before OpenSSL 1.0.0 was based on the deprecated MD5 algorithm and the encoding
867 of the distinguished name. In OpenSSL 1.0.0 and later it is based on a
868 canonical version of the DN using SHA1. This means that any directories using
869 the old form must have their links rebuilt using B<c_rehash> or similar.