6 x509 - Certificate display and signing utility
11 [B<-inform DER|PEM|NET>]
12 [B<-outform DER|PEM|NET>]
15 [B<-CAkeyform DER|PEM>]
46 [B<-signkey filename>]
53 [B<-CAserial filename>]
54 [B<-force_pubkey key>]
58 [B<-md2|-md5|-sha1|-mdc2>]
60 [B<-extfile filename>]
61 [B<-extensions section>]
66 The B<x509> command is a multi purpose certificate utility. It can be
67 used to display certificate information, convert certificates to
68 various forms, sign certificate requests like a "mini CA" or edit
69 certificate trust settings.
71 Since there are a large number of options they will split up into
76 =head2 INPUT, OUTPUT AND GENERAL PURPOSE OPTIONS
80 =item B<-inform DER|PEM|NET>
82 This specifies the input format normally the command will expect an X509
83 certificate but this can change if other options such as B<-req> are
84 present. The DER format is the DER encoding of the certificate and PEM
85 is the base64 encoding of the DER encoding with header and footer lines
86 added. The NET option is an obscure Netscape server format that is now
89 =item B<-outform DER|PEM|NET>
91 This specifies the output format, the options have the same meaning as the
96 This specifies the input filename to read a certificate from or standard input
97 if this option is not specified.
99 =item B<-out filename>
101 This specifies the output filename to write to or standard output by
104 =item B<-md2|-md5|-sha1|-mdc2>
106 the digest to use. This affects any signing or display option that uses a message
107 digest, such as the B<-fingerprint>, B<-signkey> and B<-CA> options. If not
108 specified then SHA1 is used. If the key being used to sign with is a DSA key
109 then this option has no effect: SHA1 is always used with DSA keys.
113 specifying an engine (by its unique B<id> string) will cause B<x509>
114 to attempt to obtain a functional reference to the specified engine,
115 thus initialising it if needed. The engine will then be set as the default
116 for all available algorithms.
120 =head2 DISPLAY OPTIONS
122 Note: the B<-alias> and B<-purpose> options are also display options
123 but are described in the B<TRUST SETTINGS> section.
129 prints out the certificate in text form. Full details are output including the
130 public key, signature algorithms, issuer and subject names, serial number
131 any extensions present and any trust settings.
133 =item B<-certopt option>
135 customise the output format used with B<-text>. The B<option> argument can be
136 a single option or multiple options separated by commas. The B<-certopt> switch
137 may be also be used more than once to set multiple options. See the B<TEXT OPTIONS>
138 section for more information.
142 this option prevents output of the encoded version of the request.
146 outputs the certificate's SubjectPublicKeyInfo block in PEM format.
150 this option prints out the value of the modulus of the public key
151 contained in the certificate.
155 outputs the certificate serial number.
157 =item B<-subject_hash>
159 outputs the "hash" of the certificate subject name. This is used in OpenSSL to
160 form an index to allow certificates in a directory to be looked up by subject
163 =item B<-issuer_hash>
165 outputs the "hash" of the certificate issuer name.
169 outputs the OCSP hash values for the subject name and public key.
173 synonym for "-subject_hash" for backward compatibility reasons.
175 =item B<-subject_hash_old>
177 outputs the "hash" of the certificate subject name using the older algorithm
178 as used by OpenSSL versions before 1.0.0.
180 =item B<-issuer_hash_old>
182 outputs the "hash" of the certificate issuer name using the older algorithm
183 as used by OpenSSL versions before 1.0.0.
187 outputs the subject name.
191 outputs the issuer name.
193 =item B<-nameopt option>
195 option which determines how the subject or issuer names are displayed. The
196 B<option> argument can be a single option or multiple options separated by
197 commas. Alternatively the B<-nameopt> switch may be used more than once to
198 set multiple options. See the B<NAME OPTIONS> section for more information.
202 outputs the email address(es) if any.
206 outputs the OCSP responder address(es) if any.
210 prints out the start date of the certificate, that is the notBefore date.
214 prints out the expiry date of the certificate, that is the notAfter date.
218 prints out the start and expiry dates of a certificate.
220 =item B<-checkend arg>
222 checks if the certificate expires within the next B<arg> seconds and exits
223 non-zero if yes it will expire or zero if not.
225 =item B<-fingerprint>
227 prints out the digest of the DER encoded version of the whole certificate
228 (see digest options).
232 this outputs the certificate in the form of a C source file.
236 =head2 TRUST SETTINGS
238 Please note these options are currently experimental and may well change.
240 A B<trusted certificate> is an ordinary certificate which has several
241 additional pieces of information attached to it such as the permitted
242 and prohibited uses of the certificate and an "alias".
244 Normally when a certificate is being verified at least one certificate
245 must be "trusted". By default a trusted certificate must be stored
246 locally and must be a root CA: any certificate chain ending in this CA
247 is then usable for any purpose.
249 Trust settings currently are only used with a root CA. They allow a finer
250 control over the purposes the root CA can be used for. For example a CA
251 may be trusted for SSL client but not SSL server use.
253 See the description of the B<verify> utility for more information on the
254 meaning of trust settings.
256 Future versions of OpenSSL will recognize trust settings on any
257 certificate: not just root CAs.
264 this causes B<x509> to output a B<trusted> certificate. An ordinary
265 or trusted certificate can be input but by default an ordinary
266 certificate is output and any trust settings are discarded. With the
267 B<-trustout> option a trusted certificate is output. A trusted
268 certificate is automatically output if any trust settings are modified.
270 =item B<-setalias arg>
272 sets the alias of the certificate. This will allow the certificate
273 to be referred to using a nickname for example "Steve's Certificate".
277 outputs the certificate alias, if any.
281 clears all the permitted or trusted uses of the certificate.
285 clears all the prohibited or rejected uses of the certificate.
287 =item B<-addtrust arg>
289 adds a trusted certificate use. Any object name can be used here
290 but currently only B<clientAuth> (SSL client use), B<serverAuth>
291 (SSL server use) and B<emailProtection> (S/MIME email) are used.
292 Other OpenSSL applications may define additional uses.
294 =item B<-addreject arg>
296 adds a prohibited use. It accepts the same values as the B<-addtrust>
301 this option performs tests on the certificate extensions and outputs
302 the results. For a more complete description see the B<CERTIFICATE
307 =head2 SIGNING OPTIONS
309 The B<x509> utility can be used to sign certificates and requests: it
310 can thus behave like a "mini CA".
314 =item B<-signkey filename>
316 this option causes the input file to be self signed using the supplied
319 If the input file is a certificate it sets the issuer name to the
320 subject name (i.e. makes it self signed) changes the public key to the
321 supplied value and changes the start and end dates. The start date is
322 set to the current time and the end date is set to a value determined
323 by the B<-days> option. Any certificate extensions are retained unless
324 the B<-clrext> option is supplied.
326 If the input is a certificate request then a self signed certificate
327 is created using the supplied private key using the subject name in
332 the key password source. For more information about the format of B<arg>
333 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
337 delete any extensions from a certificate. This option is used when a
338 certificate is being created from another certificate (for example with
339 the B<-signkey> or the B<-CA> options). Normally all extensions are
342 =item B<-keyform PEM|DER>
344 specifies the format (DER or PEM) of the private key file used in the
349 specifies the number of days to make a certificate valid for. The default
354 converts a certificate into a certificate request. The B<-signkey> option
355 is used to pass the required private key.
359 by default a certificate is expected on input. With this option a
360 certificate request is expected instead.
362 =item B<-set_serial n>
364 specifies the serial number to use. This option can be used with either
365 the B<-signkey> or B<-CA> options. If used in conjunction with the B<-CA>
366 option the serial number file (as specified by the B<-CAserial> or
367 B<-CAcreateserial> options) is not used.
369 The serial number can be decimal or hex (if preceded by B<0x>). Negative
370 serial numbers can also be specified but their use is not recommended.
372 =item B<-CA filename>
374 specifies the CA certificate to be used for signing. When this option is
375 present B<x509> behaves like a "mini CA". The input file is signed by this
376 CA using this option: that is its issuer name is set to the subject name
377 of the CA and it is digitally signed using the CAs private key.
379 This option is normally combined with the B<-req> option. Without the
380 B<-req> option the input is a certificate which must be self signed.
382 =item B<-CAkey filename>
384 sets the CA private key to sign a certificate with. If this option is
385 not specified then it is assumed that the CA private key is present in
386 the CA certificate file.
388 =item B<-CAserial filename>
390 sets the CA serial number file to use.
392 When the B<-CA> option is used to sign a certificate it uses a serial
393 number specified in a file. This file consist of one line containing
394 an even number of hex digits with the serial number to use. After each
395 use the serial number is incremented and written out to the file again.
397 The default filename consists of the CA certificate file base name with
398 ".srl" appended. For example if the CA certificate file is called
399 "mycacert.pem" it expects to find a serial number file called "mycacert.srl".
401 =item B<-CAcreateserial>
403 with this option the CA serial number file is created if it does not exist:
404 it will contain the serial number "02" and the certificate being signed will
405 have the 1 as its serial number. Normally if the B<-CA> option is specified
406 and the serial number file does not exist it is an error.
408 =item B<-extfile filename>
410 file containing certificate extensions to use. If not specified then
411 no extensions are added to the certificate.
413 =item B<-extensions section>
415 the section to add certificate extensions from. If this option is not
416 specified then the extensions should either be contained in the unnamed
417 (default) section or the default section should contain a variable called
418 "extensions" which contains the section to use. See the
419 L<x509v3_config(5)|x509v3_config(5)> manual page for details of the
420 extension section format.
422 =item B<-force_pubkey key>
424 when a certificate is created set its public key to B<key> instead of the
425 key in the certificate or certificate request. This option is useful for
426 creating certificates where the algorithm can't normally sign requests, for
429 The format or B<key> can be specified using the B<-keyform> option.
435 The B<nameopt> command line switch determines how the subject and issuer
436 names are displayed. If no B<nameopt> switch is present the default "oneline"
437 format is used which is compatible with previous versions of OpenSSL.
438 Each option is described in detail below, all options can be preceded by
439 a B<-> to turn the option off. Only the first four will normally be used.
445 use the old format. This is equivalent to specifying no name options at all.
449 displays names compatible with RFC2253 equivalent to B<esc_2253>, B<esc_ctrl>,
450 B<esc_msb>, B<utf8>, B<dump_nostr>, B<dump_unknown>, B<dump_der>,
451 B<sep_comma_plus>, B<dn_rev> and B<sname>.
455 a oneline format which is more readable than RFC2253. It is equivalent to
456 specifying the B<esc_2253>, B<esc_ctrl>, B<esc_msb>, B<utf8>, B<dump_nostr>,
457 B<dump_der>, B<use_quote>, B<sep_comma_plus_space>, B<space_eq> and B<sname>
462 a multiline format. It is equivalent B<esc_ctrl>, B<esc_msb>, B<sep_multiline>,
463 B<space_eq>, B<lname> and B<align>.
467 escape the "special" characters required by RFC2253 in a field That is
468 B<,+"E<lt>E<gt>;>. Additionally B<#> is escaped at the beginning of a string
469 and a space character at the beginning or end of a string.
473 escape control characters. That is those with ASCII values less than
474 0x20 (space) and the delete (0x7f) character. They are escaped using the
475 RFC2253 \XX notation (where XX are two hex digits representing the
480 escape characters with the MSB set, that is with ASCII values larger than
485 escapes some characters by surrounding the whole string with B<"> characters,
486 without the option all escaping is done with the B<\> character.
490 convert all strings to UTF8 format first. This is required by RFC2253. If
491 you are lucky enough to have a UTF8 compatible terminal then the use
492 of this option (and B<not> setting B<esc_msb>) may result in the correct
493 display of multibyte (international) characters. Is this option is not
494 present then multibyte characters larger than 0xff will be represented
495 using the format \UXXXX for 16 bits and \WXXXXXXXX for 32 bits.
496 Also if this option is off any UTF8Strings will be converted to their
497 character form first.
501 this option does not attempt to interpret multibyte characters in any
502 way. That is their content octets are merely dumped as though one octet
503 represents each character. This is useful for diagnostic purposes but
504 will result in rather odd looking output.
508 show the type of the ASN1 character string. The type precedes the
509 field contents. For example "BMPSTRING: Hello World".
513 when this option is set any fields that need to be hexdumped will
514 be dumped using the DER encoding of the field. Otherwise just the
515 content octets will be displayed. Both options use the RFC2253
520 dump non character string types (for example OCTET STRING) if this
521 option is not set then non character string types will be displayed
522 as though each content octet represents a single character.
526 dump all fields. This option when used with B<dump_der> allows the
527 DER encoding of the structure to be unambiguously determined.
529 =item B<dump_unknown>
531 dump any field whose OID is not recognised by OpenSSL.
533 =item B<sep_comma_plus>, B<sep_comma_plus_space>, B<sep_semi_plus_space>,
536 these options determine the field separators. The first character is
537 between RDNs and the second between multiple AVAs (multiple AVAs are
538 very rare and their use is discouraged). The options ending in
539 "space" additionally place a space after the separator to make it
540 more readable. The B<sep_multiline> uses a linefeed character for
541 the RDN separator and a spaced B<+> for the AVA separator. It also
542 indents the fields by four characters. If no field separator is specified
543 then B<sep_comma_plus_space> is used by default.
547 reverse the fields of the DN. This is required by RFC2253. As a side
548 effect this also reverses the order of multiple AVAs but this is
551 =item B<nofname>, B<sname>, B<lname>, B<oid>
553 these options alter how the field name is displayed. B<nofname> does
554 not display the field at all. B<sname> uses the "short name" form
555 (CN for commonName for example). B<lname> uses the long form.
556 B<oid> represents the OID in numerical form and is useful for
561 align field values for a more readable output. Only usable with
566 places spaces round the B<=> character which follows the field
573 As well as customising the name output format, it is also possible to
574 customise the actual fields printed using the B<certopt> options when
575 the B<text> option is present. The default behaviour is to print all fields.
581 use the old format. This is equivalent to specifying no output options at all.
585 don't print header information: that is the lines saying "Certificate" and "Data".
589 don't print out the version number.
593 don't print out the serial number.
597 don't print out the signature algorithm used.
601 don't print the validity, that is the B<notBefore> and B<notAfter> fields.
605 don't print out the subject name.
609 don't print out the issuer name.
613 don't print out the public key.
617 don't give a hexadecimal dump of the certificate signature.
621 don't print out certificate trust information.
623 =item B<no_extensions>
625 don't print out any X509V3 extensions.
629 retain default extension behaviour: attempt to print out unsupported certificate extensions.
633 print an error message for unsupported certificate extensions.
637 ASN1 parse unsupported extensions.
641 hex dump unsupported extensions.
645 the value used by the B<ca> utility, equivalent to B<no_issuer>, B<no_pubkey>, B<no_header>,
646 B<no_version>, B<no_sigdump> and B<no_signame>.
652 Note: in these examples the '\' means the example should be all on one
655 Display the contents of a certificate:
657 openssl x509 -in cert.pem -noout -text
659 Display the certificate serial number:
661 openssl x509 -in cert.pem -noout -serial
663 Display the certificate subject name:
665 openssl x509 -in cert.pem -noout -subject
667 Display the certificate subject name in RFC2253 form:
669 openssl x509 -in cert.pem -noout -subject -nameopt RFC2253
671 Display the certificate subject name in oneline form on a terminal
674 openssl x509 -in cert.pem -noout -subject -nameopt oneline,-esc_msb
676 Display the certificate MD5 fingerprint:
678 openssl x509 -in cert.pem -noout -fingerprint
680 Display the certificate SHA1 fingerprint:
682 openssl x509 -sha1 -in cert.pem -noout -fingerprint
684 Convert a certificate from PEM to DER format:
686 openssl x509 -in cert.pem -inform PEM -out cert.der -outform DER
688 Convert a certificate to a certificate request:
690 openssl x509 -x509toreq -in cert.pem -out req.pem -signkey key.pem
692 Convert a certificate request into a self signed certificate using
695 openssl x509 -req -in careq.pem -extfile openssl.cnf -extensions v3_ca \
696 -signkey key.pem -out cacert.pem
698 Sign a certificate request using the CA certificate above and add user
699 certificate extensions:
701 openssl x509 -req -in req.pem -extfile openssl.cnf -extensions v3_usr \
702 -CA cacert.pem -CAkey key.pem -CAcreateserial
705 Set a certificate to be trusted for SSL client use and change set its alias to
708 openssl x509 -in cert.pem -addtrust clientAuth \
709 -setalias "Steve's Class 1 CA" -out trust.pem
713 The PEM format uses the header and footer lines:
715 -----BEGIN CERTIFICATE-----
716 -----END CERTIFICATE-----
718 it will also handle files containing:
720 -----BEGIN X509 CERTIFICATE-----
721 -----END X509 CERTIFICATE-----
723 Trusted certificates have the lines
725 -----BEGIN TRUSTED CERTIFICATE-----
726 -----END TRUSTED CERTIFICATE-----
728 The conversion to UTF8 format used with the name options assumes that
729 T61Strings use the ISO8859-1 character set. This is wrong but Netscape
730 and MSIE do this as do many certificates. So although this is incorrect
731 it is more likely to display the majority of certificates correctly.
733 The B<-fingerprint> option takes the digest of the DER encoded certificate.
734 This is commonly called a "fingerprint". Because of the nature of message
735 digests the fingerprint of a certificate is unique to that certificate and
736 two certificates with the same fingerprint can be considered to be the same.
738 The Netscape fingerprint uses MD5 whereas MSIE uses SHA1.
740 The B<-email> option searches the subject name and the subject alternative
741 name extension. Only unique email addresses will be printed out: it will
742 not print the same address more than once.
744 =head1 CERTIFICATE EXTENSIONS
746 The B<-purpose> option checks the certificate extensions and determines
747 what the certificate can be used for. The actual checks done are rather
748 complex and include various hacks and workarounds to handle broken
749 certificates and software.
751 The same code is used when verifying untrusted certificates in chains
752 so this section is useful if a chain is rejected by the verify code.
754 The basicConstraints extension CA flag is used to determine whether the
755 certificate can be used as a CA. If the CA flag is true then it is a CA,
756 if the CA flag is false then it is not a CA. B<All> CAs should have the
759 If the basicConstraints extension is absent then the certificate is
760 considered to be a "possible CA" other extensions are checked according
761 to the intended use of the certificate. A warning is given in this case
762 because the certificate should really not be regarded as a CA: however
763 it is allowed to be a CA to work around some broken software.
765 If the certificate is a V1 certificate (and thus has no extensions) and
766 it is self signed it is also assumed to be a CA but a warning is again
767 given: this is to work around the problem of Verisign roots which are V1
768 self signed certificates.
770 If the keyUsage extension is present then additional restraints are
771 made on the uses of the certificate. A CA certificate B<must> have the
772 keyCertSign bit set if the keyUsage extension is present.
774 The extended key usage extension places additional restrictions on the
775 certificate uses. If this extension is present (whether critical or not)
776 the key can only be used for the purposes specified.
778 A complete description of each test is given below. The comments about
779 basicConstraints and keyUsage and V1 certificates above apply to B<all>
787 The extended key usage extension must be absent or include the "web client
788 authentication" OID. keyUsage must be absent or it must have the
789 digitalSignature bit set. Netscape certificate type must be absent or it must
790 have the SSL client bit set.
792 =item B<SSL Client CA>
794 The extended key usage extension must be absent or include the "web client
795 authentication" OID. Netscape certificate type must be absent or it must have
796 the SSL CA bit set: this is used as a work around if the basicConstraints
801 The extended key usage extension must be absent or include the "web server
802 authentication" and/or one of the SGC OIDs. keyUsage must be absent or it
803 must have the digitalSignature, the keyEncipherment set or both bits set.
804 Netscape certificate type must be absent or have the SSL server bit set.
806 =item B<SSL Server CA>
808 The extended key usage extension must be absent or include the "web server
809 authentication" and/or one of the SGC OIDs. Netscape certificate type must
810 be absent or the SSL CA bit must be set: this is used as a work around if the
811 basicConstraints extension is absent.
813 =item B<Netscape SSL Server>
815 For Netscape SSL clients to connect to an SSL server it must have the
816 keyEncipherment bit set if the keyUsage extension is present. This isn't
817 always valid because some cipher suites use the key for digital signing.
818 Otherwise it is the same as a normal SSL server.
820 =item B<Common S/MIME Client Tests>
822 The extended key usage extension must be absent or include the "email
823 protection" OID. Netscape certificate type must be absent or should have the
824 S/MIME bit set. If the S/MIME bit is not set in netscape certificate type
825 then the SSL client bit is tolerated as an alternative but a warning is shown:
826 this is because some Verisign certificates don't set the S/MIME bit.
828 =item B<S/MIME Signing>
830 In addition to the common S/MIME client tests the digitalSignature bit must
831 be set if the keyUsage extension is present.
833 =item B<S/MIME Encryption>
835 In addition to the common S/MIME tests the keyEncipherment bit must be set
836 if the keyUsage extension is present.
840 The extended key usage extension must be absent or include the "email
841 protection" OID. Netscape certificate type must be absent or must have the
842 S/MIME CA bit set: this is used as a work around if the basicConstraints
847 The keyUsage extension must be absent or it must have the CRL signing bit
850 =item B<CRL Signing CA>
852 The normal CA tests apply. Except in this case the basicConstraints extension
859 Extensions in certificates are not transferred to certificate requests and
862 It is possible to produce invalid certificates or requests by specifying the
863 wrong private key or using inconsistent options in some cases: these should
866 There should be options to explicitly set such things as start and end
867 dates rather than an offset from the current time.
869 The code to implement the verify behaviour described in the B<TRUST SETTINGS>
870 is currently being developed. It thus describes the intended behaviour rather
871 than the current behaviour. It is hoped that it will represent reality in
872 OpenSSL 0.9.5 and later.
876 L<req(1)|req(1)>, L<ca(1)|ca(1)>, L<genrsa(1)|genrsa(1)>,
877 L<gendsa(1)|gendsa(1)>, L<verify(1)|verify(1)>,
878 L<x509v3_config(5)|x509v3_config(5)>
882 Before OpenSSL 0.9.8, the default digest for RSA keys was MD5.
884 The hash algorithm used in the B<-subject_hash> and B<-issuer_hash> options
885 before OpenSSL 1.0.0 was based on the deprecated MD5 algorithm and the encoding
886 of the distinguished name. In OpenSSL 1.0.0 and later it is based on a
887 canonical version of the DN using SHA1. This means that any directories using
888 the old form must have their links rebuilt using B<c_rehash> or similar.