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>]
57 [B<-md2|-md5|-sha1|-mdc2>]
59 [B<-extfile filename>]
60 [B<-extensions section>]
65 The B<x509> command is a multi purpose certificate utility. It can be
66 used to display certificate information, convert certificates to
67 various forms, sign certificate requests like a "mini CA" or edit
68 certificate trust settings.
70 Since there are a large number of options they will split up into
75 =head2 INPUT, OUTPUT AND GENERAL PURPOSE OPTIONS
79 =item B<-inform DER|PEM|NET>
81 This specifies the input format normally the command will expect an X509
82 certificate but this can change if other options such as B<-req> are
83 present. The DER format is the DER encoding of the certificate and PEM
84 is the base64 encoding of the DER encoding with header and footer lines
85 added. The NET option is an obscure Netscape server format that is now
88 =item B<-outform DER|PEM|NET>
90 This specifies the output format, the options have the same meaning as the
95 This specifies the input filename to read a certificate from or standard input
96 if this option is not specified.
98 =item B<-out filename>
100 This specifies the output filename to write to or standard output by
103 =item B<-md2|-md5|-sha1|-mdc2>
105 the digest to use. This affects any signing or display option that uses a message
106 digest, such as the B<-fingerprint>, B<-signkey> and B<-CA> options. If not
107 specified then SHA1 is used. If the key being used to sign with is a DSA key
108 then this option has no effect: SHA1 is always used with DSA keys.
112 specifying an engine (by its unique B<id> string) will cause B<x509>
113 to attempt to obtain a functional reference to the specified engine,
114 thus initialising it if needed. The engine will then be set as the default
115 for all available algorithms.
119 =head2 DISPLAY OPTIONS
121 Note: the B<-alias> and B<-purpose> options are also display options
122 but are described in the B<TRUST SETTINGS> section.
128 prints out the certificate in text form. Full details are output including the
129 public key, signature algorithms, issuer and subject names, serial number
130 any extensions present and any trust settings.
132 =item B<-certopt option>
134 customise the output format used with B<-text>. The B<option> argument can be
135 a single option or multiple options separated by commas. The B<-certopt> switch
136 may be also be used more than once to set multiple options. See the B<TEXT OPTIONS>
137 section for more information.
141 this option prevents output of the encoded version of the request.
145 outputs the the certificate's SubjectPublicKeyInfo block in PEM format.
149 this option prints out the value of the modulus of the public key
150 contained in the certificate.
154 outputs the certificate serial number.
156 =item B<-subject_hash>
158 outputs the "hash" of the certificate subject name. This is used in OpenSSL to
159 form an index to allow certificates in a directory to be looked up by subject
162 =item B<-issuer_hash>
164 outputs the "hash" of the certificate issuer name.
168 outputs the OCSP hash values for the subject name and public key.
172 synonym for "-subject_hash" for backward compatibility reasons.
174 =item B<-subject_hash_old>
176 outputs the "hash" of the certificate subject name using the older algorithm
177 as used by OpenSSL versions before 1.0.0.
179 =item B<-issuer_hash_old>
181 outputs the "hash" of the certificate issuer name using the older algorithm
182 as used by OpenSSL versions before 1.0.0.
186 outputs the subject name.
190 outputs the issuer name.
192 =item B<-nameopt option>
194 option which determines how the subject or issuer names are displayed. The
195 B<option> argument can be a single option or multiple options separated by
196 commas. Alternatively the B<-nameopt> switch may be used more than once to
197 set multiple options. See the B<NAME OPTIONS> section for more information.
201 outputs the email address(es) if any.
205 outputs the OCSP responder address(es) if any.
209 prints out the start date of the certificate, that is the notBefore date.
213 prints out the expiry date of the certificate, that is the notAfter date.
217 prints out the start and expiry dates of a certificate.
219 =item B<-checkend arg>
221 checks if the certificate expires within the next B<arg> seconds and exits
222 non-zero if yes it will expire or zero if not.
224 =item B<-fingerprint>
226 prints out the digest of the DER encoded version of the whole certificate
227 (see digest options).
231 this outputs the certificate in the form of a C source file.
235 =head2 TRUST SETTINGS
237 Please note these options are currently experimental and may well change.
239 A B<trusted certificate> is an ordinary certificate which has several
240 additional pieces of information attached to it such as the permitted
241 and prohibited uses of the certificate and an "alias".
243 Normally when a certificate is being verified at least one certificate
244 must be "trusted". By default a trusted certificate must be stored
245 locally and must be a root CA: any certificate chain ending in this CA
246 is then usable for any purpose.
248 Trust settings currently are only used with a root CA. They allow a finer
249 control over the purposes the root CA can be used for. For example a CA
250 may be trusted for SSL client but not SSL server use.
252 See the description of the B<verify> utility for more information on the
253 meaning of trust settings.
255 Future versions of OpenSSL will recognize trust settings on any
256 certificate: not just root CAs.
263 this causes B<x509> to output a B<trusted> certificate. An ordinary
264 or trusted certificate can be input but by default an ordinary
265 certificate is output and any trust settings are discarded. With the
266 B<-trustout> option a trusted certificate is output. A trusted
267 certificate is automatically output if any trust settings are modified.
269 =item B<-setalias arg>
271 sets the alias of the certificate. This will allow the certificate
272 to be referred to using a nickname for example "Steve's Certificate".
276 outputs the certificate alias, if any.
280 clears all the permitted or trusted uses of the certificate.
284 clears all the prohibited or rejected uses of the certificate.
286 =item B<-addtrust arg>
288 adds a trusted certificate use. Any object name can be used here
289 but currently only B<clientAuth> (SSL client use), B<serverAuth>
290 (SSL server use) and B<emailProtection> (S/MIME email) are used.
291 Other OpenSSL applications may define additional uses.
293 =item B<-addreject arg>
295 adds a prohibited use. It accepts the same values as the B<-addtrust>
300 this option performs tests on the certificate extensions and outputs
301 the results. For a more complete description see the B<CERTIFICATE
306 =head2 SIGNING OPTIONS
308 The B<x509> utility can be used to sign certificates and requests: it
309 can thus behave like a "mini CA".
313 =item B<-signkey filename>
315 this option causes the input file to be self signed using the supplied
318 If the input file is a certificate it sets the issuer name to the
319 subject name (i.e. makes it self signed) changes the public key to the
320 supplied value and changes the start and end dates. The start date is
321 set to the current time and the end date is set to a value determined
322 by the B<-days> option. Any certificate extensions are retained unless
323 the B<-clrext> option is supplied.
325 If the input is a certificate request then a self signed certificate
326 is created using the supplied private key using the subject name in
331 the key password source. For more information about the format of B<arg>
332 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
336 delete any extensions from a certificate. This option is used when a
337 certificate is being created from another certificate (for example with
338 the B<-signkey> or the B<-CA> options). Normally all extensions are
341 =item B<-keyform PEM|DER>
343 specifies the format (DER or PEM) of the private key file used in the
348 specifies the number of days to make a certificate valid for. The default
353 converts a certificate into a certificate request. The B<-signkey> option
354 is used to pass the required private key.
358 by default a certificate is expected on input. With this option a
359 certificate request is expected instead.
361 =item B<-set_serial n>
363 specifies the serial number to use. This option can be used with either
364 the B<-signkey> or B<-CA> options. If used in conjunction with the B<-CA>
365 option the serial number file (as specified by the B<-CAserial> or
366 B<-CAcreateserial> options) is not used.
368 The serial number can be decimal or hex (if preceded by B<0x>). Negative
369 serial numbers can also be specified but their use is not recommended.
371 =item B<-CA filename>
373 specifies the CA certificate to be used for signing. When this option is
374 present B<x509> behaves like a "mini CA". The input file is signed by this
375 CA using this option: that is its issuer name is set to the subject name
376 of the CA and it is digitally signed using the CAs private key.
378 This option is normally combined with the B<-req> option. Without the
379 B<-req> option the input is a certificate which must be self signed.
381 =item B<-CAkey filename>
383 sets the CA private key to sign a certificate with. If this option is
384 not specified then it is assumed that the CA private key is present in
385 the CA certificate file.
387 =item B<-CAserial filename>
389 sets the CA serial number file to use.
391 When the B<-CA> option is used to sign a certificate it uses a serial
392 number specified in a file. This file consist of one line containing
393 an even number of hex digits with the serial number to use. After each
394 use the serial number is incremented and written out to the file again.
396 The default filename consists of the CA certificate file base name with
397 ".srl" appended. For example if the CA certificate file is called
398 "mycacert.pem" it expects to find a serial number file called "mycacert.srl".
400 =item B<-CAcreateserial>
402 with this option the CA serial number file is created if it does not exist:
403 it will contain the serial number "02" and the certificate being signed will
404 have the 1 as its serial number. Normally if the B<-CA> option is specified
405 and the serial number file does not exist it is an error.
407 =item B<-extfile filename>
409 file containing certificate extensions to use. If not specified then
410 no extensions are added to the certificate.
412 =item B<-extensions section>
414 the section to add certificate extensions from. If this option is not
415 specified then the extensions should either be contained in the unnamed
416 (default) section or the default section should contain a variable called
417 "extensions" which contains the section to use. See the
418 L<x509v3_config(5)|x509v3_config(5)> manual page for details of the
419 extension section format.
425 The B<nameopt> command line switch determines how the subject and issuer
426 names are displayed. If no B<nameopt> switch is present the default "oneline"
427 format is used which is compatible with previous versions of OpenSSL.
428 Each option is described in detail below, all options can be preceded by
429 a B<-> to turn the option off. Only the first four will normally be used.
435 use the old format. This is equivalent to specifying no name options at all.
439 displays names compatible with RFC2253 equivalent to B<esc_2253>, B<esc_ctrl>,
440 B<esc_msb>, B<utf8>, B<dump_nostr>, B<dump_unknown>, B<dump_der>,
441 B<sep_comma_plus>, B<dn_rev> and B<sname>.
445 a oneline format which is more readable than RFC2253. It is equivalent to
446 specifying the B<esc_2253>, B<esc_ctrl>, B<esc_msb>, B<utf8>, B<dump_nostr>,
447 B<dump_der>, B<use_quote>, B<sep_comma_plus_space>, B<space_eq> and B<sname>
452 a multiline format. It is equivalent B<esc_ctrl>, B<esc_msb>, B<sep_multiline>,
453 B<space_eq>, B<lname> and B<align>.
457 escape the "special" characters required by RFC2253 in a field That is
458 B<,+"E<lt>E<gt>;>. Additionally B<#> is escaped at the beginning of a string
459 and a space character at the beginning or end of a string.
463 escape control characters. That is those with ASCII values less than
464 0x20 (space) and the delete (0x7f) character. They are escaped using the
465 RFC2253 \XX notation (where XX are two hex digits representing the
470 escape characters with the MSB set, that is with ASCII values larger than
475 escapes some characters by surrounding the whole string with B<"> characters,
476 without the option all escaping is done with the B<\> character.
480 convert all strings to UTF8 format first. This is required by RFC2253. If
481 you are lucky enough to have a UTF8 compatible terminal then the use
482 of this option (and B<not> setting B<esc_msb>) may result in the correct
483 display of multibyte (international) characters. Is this option is not
484 present then multibyte characters larger than 0xff will be represented
485 using the format \UXXXX for 16 bits and \WXXXXXXXX for 32 bits.
486 Also if this option is off any UTF8Strings will be converted to their
487 character form first.
491 this option does not attempt to interpret multibyte characters in any
492 way. That is their content octets are merely dumped as though one octet
493 represents each character. This is useful for diagnostic purposes but
494 will result in rather odd looking output.
498 show the type of the ASN1 character string. The type precedes the
499 field contents. For example "BMPSTRING: Hello World".
503 when this option is set any fields that need to be hexdumped will
504 be dumped using the DER encoding of the field. Otherwise just the
505 content octets will be displayed. Both options use the RFC2253
510 dump non character string types (for example OCTET STRING) if this
511 option is not set then non character string types will be displayed
512 as though each content octet represents a single character.
516 dump all fields. This option when used with B<dump_der> allows the
517 DER encoding of the structure to be unambiguously determined.
519 =item B<dump_unknown>
521 dump any field whose OID is not recognised by OpenSSL.
523 =item B<sep_comma_plus>, B<sep_comma_plus_space>, B<sep_semi_plus_space>,
526 these options determine the field separators. The first character is
527 between RDNs and the second between multiple AVAs (multiple AVAs are
528 very rare and their use is discouraged). The options ending in
529 "space" additionally place a space after the separator to make it
530 more readable. The B<sep_multiline> uses a linefeed character for
531 the RDN separator and a spaced B<+> for the AVA separator. It also
532 indents the fields by four characters. If no field separator is specified
533 then B<sep_comma_plus_space> is used by default.
537 reverse the fields of the DN. This is required by RFC2253. As a side
538 effect this also reverses the order of multiple AVAs but this is
541 =item B<nofname>, B<sname>, B<lname>, B<oid>
543 these options alter how the field name is displayed. B<nofname> does
544 not display the field at all. B<sname> uses the "short name" form
545 (CN for commonName for example). B<lname> uses the long form.
546 B<oid> represents the OID in numerical form and is useful for
551 align field values for a more readable output. Only usable with
556 places spaces round the B<=> character which follows the field
563 As well as customising the name output format, it is also possible to
564 customise the actual fields printed using the B<certopt> options when
565 the B<text> option is present. The default behaviour is to print all fields.
571 use the old format. This is equivalent to specifying no output options at all.
575 don't print header information: that is the lines saying "Certificate" and "Data".
579 don't print out the version number.
583 don't print out the serial number.
587 don't print out the signature algorithm used.
591 don't print the validity, that is the B<notBefore> and B<notAfter> fields.
595 don't print out the subject name.
599 don't print out the issuer name.
603 don't print out the public key.
607 don't give a hexadecimal dump of the certificate signature.
611 don't print out certificate trust information.
613 =item B<no_extensions>
615 don't print out any X509V3 extensions.
619 retain default extension behaviour: attempt to print out unsupported certificate extensions.
623 print an error message for unsupported certificate extensions.
627 ASN1 parse unsupported extensions.
631 hex dump unsupported extensions.
635 the value used by the B<ca> utility, equivalent to B<no_issuer>, B<no_pubkey>, B<no_header>,
636 B<no_version>, B<no_sigdump> and B<no_signame>.
642 Note: in these examples the '\' means the example should be all on one
645 Display the contents of a certificate:
647 openssl x509 -in cert.pem -noout -text
649 Display the certificate serial number:
651 openssl x509 -in cert.pem -noout -serial
653 Display the certificate subject name:
655 openssl x509 -in cert.pem -noout -subject
657 Display the certificate subject name in RFC2253 form:
659 openssl x509 -in cert.pem -noout -subject -nameopt RFC2253
661 Display the certificate subject name in oneline form on a terminal
664 openssl x509 -in cert.pem -noout -subject -nameopt oneline,-esc_msb
666 Display the certificate MD5 fingerprint:
668 openssl x509 -in cert.pem -noout -fingerprint
670 Display the certificate SHA1 fingerprint:
672 openssl x509 -sha1 -in cert.pem -noout -fingerprint
674 Convert a certificate from PEM to DER format:
676 openssl x509 -in cert.pem -inform PEM -out cert.der -outform DER
678 Convert a certificate to a certificate request:
680 openssl x509 -x509toreq -in cert.pem -out req.pem -signkey key.pem
682 Convert a certificate request into a self signed certificate using
685 openssl x509 -req -in careq.pem -extfile openssl.cnf -extensions v3_ca \
686 -signkey key.pem -out cacert.pem
688 Sign a certificate request using the CA certificate above and add user
689 certificate extensions:
691 openssl x509 -req -in req.pem -extfile openssl.cnf -extensions v3_usr \
692 -CA cacert.pem -CAkey key.pem -CAcreateserial
695 Set a certificate to be trusted for SSL client use and change set its alias to
698 openssl x509 -in cert.pem -addtrust clientAuth \
699 -setalias "Steve's Class 1 CA" -out trust.pem
703 The PEM format uses the header and footer lines:
705 -----BEGIN CERTIFICATE-----
706 -----END CERTIFICATE-----
708 it will also handle files containing:
710 -----BEGIN X509 CERTIFICATE-----
711 -----END X509 CERTIFICATE-----
713 Trusted certificates have the lines
715 -----BEGIN TRUSTED CERTIFICATE-----
716 -----END TRUSTED CERTIFICATE-----
718 The conversion to UTF8 format used with the name options assumes that
719 T61Strings use the ISO8859-1 character set. This is wrong but Netscape
720 and MSIE do this as do many certificates. So although this is incorrect
721 it is more likely to display the majority of certificates correctly.
723 The B<-fingerprint> option takes the digest of the DER encoded certificate.
724 This is commonly called a "fingerprint". Because of the nature of message
725 digests the fingerprint of a certificate is unique to that certificate and
726 two certificates with the same fingerprint can be considered to be the same.
728 The Netscape fingerprint uses MD5 whereas MSIE uses SHA1.
730 The B<-email> option searches the subject name and the subject alternative
731 name extension. Only unique email addresses will be printed out: it will
732 not print the same address more than once.
734 =head1 CERTIFICATE EXTENSIONS
736 The B<-purpose> option checks the certificate extensions and determines
737 what the certificate can be used for. The actual checks done are rather
738 complex and include various hacks and workarounds to handle broken
739 certificates and software.
741 The same code is used when verifying untrusted certificates in chains
742 so this section is useful if a chain is rejected by the verify code.
744 The basicConstraints extension CA flag is used to determine whether the
745 certificate can be used as a CA. If the CA flag is true then it is a CA,
746 if the CA flag is false then it is not a CA. B<All> CAs should have the
749 If the basicConstraints extension is absent then the certificate is
750 considered to be a "possible CA" other extensions are checked according
751 to the intended use of the certificate. A warning is given in this case
752 because the certificate should really not be regarded as a CA: however
753 it is allowed to be a CA to work around some broken software.
755 If the certificate is a V1 certificate (and thus has no extensions) and
756 it is self signed it is also assumed to be a CA but a warning is again
757 given: this is to work around the problem of Verisign roots which are V1
758 self signed certificates.
760 If the keyUsage extension is present then additional restraints are
761 made on the uses of the certificate. A CA certificate B<must> have the
762 keyCertSign bit set if the keyUsage extension is present.
764 The extended key usage extension places additional restrictions on the
765 certificate uses. If this extension is present (whether critical or not)
766 the key can only be used for the purposes specified.
768 A complete description of each test is given below. The comments about
769 basicConstraints and keyUsage and V1 certificates above apply to B<all>
777 The extended key usage extension must be absent or include the "web client
778 authentication" OID. keyUsage must be absent or it must have the
779 digitalSignature bit set. Netscape certificate type must be absent or it must
780 have the SSL client bit set.
782 =item B<SSL Client CA>
784 The extended key usage extension must be absent or include the "web client
785 authentication" OID. Netscape certificate type must be absent or it must have
786 the SSL CA bit set: this is used as a work around if the basicConstraints
791 The extended key usage extension must be absent or include the "web server
792 authentication" and/or one of the SGC OIDs. keyUsage must be absent or it
793 must have the digitalSignature, the keyEncipherment set or both bits set.
794 Netscape certificate type must be absent or have the SSL server bit set.
796 =item B<SSL Server CA>
798 The extended key usage extension must be absent or include the "web server
799 authentication" and/or one of the SGC OIDs. Netscape certificate type must
800 be absent or the SSL CA bit must be set: this is used as a work around if the
801 basicConstraints extension is absent.
803 =item B<Netscape SSL Server>
805 For Netscape SSL clients to connect to an SSL server it must have the
806 keyEncipherment bit set if the keyUsage extension is present. This isn't
807 always valid because some cipher suites use the key for digital signing.
808 Otherwise it is the same as a normal SSL server.
810 =item B<Common S/MIME Client Tests>
812 The extended key usage extension must be absent or include the "email
813 protection" OID. Netscape certificate type must be absent or should have the
814 S/MIME bit set. If the S/MIME bit is not set in netscape certificate type
815 then the SSL client bit is tolerated as an alternative but a warning is shown:
816 this is because some Verisign certificates don't set the S/MIME bit.
818 =item B<S/MIME Signing>
820 In addition to the common S/MIME client tests the digitalSignature bit must
821 be set if the keyUsage extension is present.
823 =item B<S/MIME Encryption>
825 In addition to the common S/MIME tests the keyEncipherment bit must be set
826 if the keyUsage extension is present.
830 The extended key usage extension must be absent or include the "email
831 protection" OID. Netscape certificate type must be absent or must have the
832 S/MIME CA bit set: this is used as a work around if the basicConstraints
837 The keyUsage extension must be absent or it must have the CRL signing bit
840 =item B<CRL Signing CA>
842 The normal CA tests apply. Except in this case the basicConstraints extension
849 Extensions in certificates are not transferred to certificate requests and
852 It is possible to produce invalid certificates or requests by specifying the
853 wrong private key or using inconsistent options in some cases: these should
856 There should be options to explicitly set such things as start and end
857 dates rather than an offset from the current time.
859 The code to implement the verify behaviour described in the B<TRUST SETTINGS>
860 is currently being developed. It thus describes the intended behaviour rather
861 than the current behaviour. It is hoped that it will represent reality in
862 OpenSSL 0.9.5 and later.
866 L<req(1)|req(1)>, L<ca(1)|ca(1)>, L<genrsa(1)|genrsa(1)>,
867 L<gendsa(1)|gendsa(1)>, L<verify(1)|verify(1)>,
868 L<x509v3_config(5)|x509v3_config(5)>
872 Before OpenSSL 0.9.8, the default digest for RSA keys was MD5.
874 The hash algorithm used in the B<-subject_hash> and B<-issuer_hash> options
875 before OpenSSL 1.0.0 was based on the deprecated MD5 algorithm and the encoding
876 of the distinguished name. In OpenSSL 1.0.0 and later it is based on a
877 canonical version of the DN using SHA1. This means that any directories using
878 the old form must have their links rebuilt using B<c_rehash> or similar.