7 x509 - Certificate display and signing utility
12 [B<-inform DER|PEM|NET>]
13 [B<-outform DER|PEM|NET>]
16 [B<-CAkeyform DER|PEM>]
47 [B<-signkey filename>]
54 [B<-CAserial filename>]
55 [B<-force_pubkey key>]
59 [B<-md2|-md5|-sha1|-mdc2>]
61 [B<-extfile filename>]
62 [B<-extensions section>]
67 The B<x509> command is a multi purpose certificate utility. It can be
68 used to display certificate information, convert certificates to
69 various forms, sign certificate requests like a "mini CA" or edit
70 certificate trust settings.
72 Since there are a large number of options they will split up into
77 =head2 INPUT, OUTPUT AND GENERAL PURPOSE OPTIONS
81 =item B<-inform DER|PEM|NET>
83 This specifies the input format normally the command will expect an X509
84 certificate but this can change if other options such as B<-req> are
85 present. The DER format is the DER encoding of the certificate and PEM
86 is the base64 encoding of the DER encoding with header and footer lines
87 added. The NET option is an obscure Netscape server format that is now
90 =item B<-outform DER|PEM|NET>
92 This specifies the output format, the options have the same meaning as the
97 This specifies the input filename to read a certificate from or standard input
98 if this option is not specified.
100 =item B<-out filename>
102 This specifies the output filename to write to or standard output by
105 =item B<-md2|-md5|-sha1|-mdc2>
107 the digest to use. This affects any signing or display option that uses a message
108 digest, such as the B<-fingerprint>, B<-signkey> and B<-CA> options. If not
109 specified then SHA1 is used. If the key being used to sign with is a DSA key
110 then this option has no effect: SHA1 is always used with DSA keys.
114 specifying an engine (by its unique B<id> string) will cause B<x509>
115 to attempt to obtain a functional reference to the specified engine,
116 thus initialising it if needed. The engine will then be set as the default
117 for all available algorithms.
121 =head2 DISPLAY OPTIONS
123 Note: the B<-alias> and B<-purpose> options are also display options
124 but are described in the B<TRUST SETTINGS> section.
130 prints out the certificate in text form. Full details are output including the
131 public key, signature algorithms, issuer and subject names, serial number
132 any extensions present and any trust settings.
134 =item B<-certopt option>
136 customise the output format used with B<-text>. The B<option> argument can be
137 a single option or multiple options separated by commas. The B<-certopt> switch
138 may be also be used more than once to set multiple options. See the B<TEXT OPTIONS>
139 section for more information.
143 this option prevents output of the encoded version of the request.
147 outputs the the certificate's SubjectPublicKeyInfo block in PEM format.
151 this option prints out the value of the modulus of the public key
152 contained in the certificate.
156 outputs the certificate serial number.
158 =item B<-subject_hash>
160 outputs the "hash" of the certificate subject name. This is used in OpenSSL to
161 form an index to allow certificates in a directory to be looked up by subject
164 =item B<-issuer_hash>
166 outputs the "hash" of the certificate issuer name.
170 outputs the OCSP hash values for the subject name and public key.
174 synonym for "-subject_hash" for backward compatibility reasons.
176 =item B<-subject_hash_old>
178 outputs the "hash" of the certificate subject name using the older algorithm
179 as used by OpenSSL versions before 1.0.0.
181 =item B<-issuer_hash_old>
183 outputs the "hash" of the certificate issuer name using the older algorithm
184 as used by OpenSSL versions before 1.0.0.
188 outputs the subject name.
192 outputs the issuer name.
194 =item B<-nameopt option>
196 option which determines how the subject or issuer names are displayed. The
197 B<option> argument can be a single option or multiple options separated by
198 commas. Alternatively the B<-nameopt> switch may be used more than once to
199 set multiple options. See the B<NAME OPTIONS> section for more information.
203 outputs the email address(es) if any.
207 outputs the OCSP responder address(es) if any.
211 prints out the start date of the certificate, that is the notBefore date.
215 prints out the expiry date of the certificate, that is the notAfter date.
219 prints out the start and expiry dates of a certificate.
221 =item B<-checkend arg>
223 checks if the certificate expires within the next B<arg> seconds and exits
224 non-zero if yes it will expire or zero if not.
226 =item B<-fingerprint>
228 prints out the digest of the DER encoded version of the whole certificate
229 (see digest options).
233 this outputs the certificate in the form of a C source file.
237 =head2 TRUST SETTINGS
239 Please note these options are currently experimental and may well change.
241 A B<trusted certificate> is an ordinary certificate which has several
242 additional pieces of information attached to it such as the permitted
243 and prohibited uses of the certificate and an "alias".
245 Normally when a certificate is being verified at least one certificate
246 must be "trusted". By default a trusted certificate must be stored
247 locally and must be a root CA: any certificate chain ending in this CA
248 is then usable for any purpose.
250 Trust settings currently are only used with a root CA. They allow a finer
251 control over the purposes the root CA can be used for. For example a CA
252 may be trusted for SSL client but not SSL server use.
254 See the description of the B<verify> utility for more information on the
255 meaning of trust settings.
257 Future versions of OpenSSL will recognize trust settings on any
258 certificate: not just root CAs.
265 this causes B<x509> to output a B<trusted> certificate. An ordinary
266 or trusted certificate can be input but by default an ordinary
267 certificate is output and any trust settings are discarded. With the
268 B<-trustout> option a trusted certificate is output. A trusted
269 certificate is automatically output if any trust settings are modified.
271 =item B<-setalias arg>
273 sets the alias of the certificate. This will allow the certificate
274 to be referred to using a nickname for example "Steve's Certificate".
278 outputs the certificate alias, if any.
282 clears all the permitted or trusted uses of the certificate.
286 clears all the prohibited or rejected uses of the certificate.
288 =item B<-addtrust arg>
290 adds a trusted certificate use. Any object name can be used here
291 but currently only B<clientAuth> (SSL client use), B<serverAuth>
292 (SSL server use) and B<emailProtection> (S/MIME email) are used.
293 Other OpenSSL applications may define additional uses.
295 =item B<-addreject arg>
297 adds a prohibited use. It accepts the same values as the B<-addtrust>
302 this option performs tests on the certificate extensions and outputs
303 the results. For a more complete description see the B<CERTIFICATE
308 =head2 SIGNING OPTIONS
310 The B<x509> utility can be used to sign certificates and requests: it
311 can thus behave like a "mini CA".
315 =item B<-signkey filename>
317 this option causes the input file to be self signed using the supplied
320 If the input file is a certificate it sets the issuer name to the
321 subject name (i.e. makes it self signed) changes the public key to the
322 supplied value and changes the start and end dates. The start date is
323 set to the current time and the end date is set to a value determined
324 by the B<-days> option. Any certificate extensions are retained unless
325 the B<-clrext> option is supplied.
327 If the input is a certificate request then a self signed certificate
328 is created using the supplied private key using the subject name in
333 the key password source. For more information about the format of B<arg>
334 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
338 delete any extensions from a certificate. This option is used when a
339 certificate is being created from another certificate (for example with
340 the B<-signkey> or the B<-CA> options). Normally all extensions are
343 =item B<-keyform PEM|DER>
345 specifies the format (DER or PEM) of the private key file used in the
350 specifies the number of days to make a certificate valid for. The default
355 converts a certificate into a certificate request. The B<-signkey> option
356 is used to pass the required private key.
360 by default a certificate is expected on input. With this option a
361 certificate request is expected instead.
363 =item B<-set_serial n>
365 specifies the serial number to use. This option can be used with either
366 the B<-signkey> or B<-CA> options. If used in conjunction with the B<-CA>
367 option the serial number file (as specified by the B<-CAserial> or
368 B<-CAcreateserial> options) is not used.
370 The serial number can be decimal or hex (if preceded by B<0x>). Negative
371 serial numbers can also be specified but their use is not recommended.
373 =item B<-CA filename>
375 specifies the CA certificate to be used for signing. When this option is
376 present B<x509> behaves like a "mini CA". The input file is signed by this
377 CA using this option: that is its issuer name is set to the subject name
378 of the CA and it is digitally signed using the CAs private key.
380 This option is normally combined with the B<-req> option. Without the
381 B<-req> option the input is a certificate which must be self signed.
383 =item B<-CAkey filename>
385 sets the CA private key to sign a certificate with. If this option is
386 not specified then it is assumed that the CA private key is present in
387 the CA certificate file.
389 =item B<-CAserial filename>
391 sets the CA serial number file to use.
393 When the B<-CA> option is used to sign a certificate it uses a serial
394 number specified in a file. This file consist of one line containing
395 an even number of hex digits with the serial number to use. After each
396 use the serial number is incremented and written out to the file again.
398 The default filename consists of the CA certificate file base name with
399 ".srl" appended. For example if the CA certificate file is called
400 "mycacert.pem" it expects to find a serial number file called "mycacert.srl".
402 =item B<-CAcreateserial>
404 with this option the CA serial number file is created if it does not exist:
405 it will contain the serial number "02" and the certificate being signed will
406 have the 1 as its serial number. Normally if the B<-CA> option is specified
407 and the serial number file does not exist it is an error.
409 =item B<-extfile filename>
411 file containing certificate extensions to use. If not specified then
412 no extensions are added to the certificate.
414 =item B<-extensions section>
416 the section to add certificate extensions from. If this option is not
417 specified then the extensions should either be contained in the unnamed
418 (default) section or the default section should contain a variable called
419 "extensions" which contains the section to use. See the
420 L<x509v3_config(5)|x509v3_config(5)> manual page for details of the
421 extension section format.
423 =item B<-force_pubkey key>
425 when a certificate is created set its public key to B<key> instead of the
426 key in the certificate or certificate request. This option is useful for
427 creating certificates where the algorithm can't normally sign requests, for
430 The format or B<key> can be specified using the B<-keyform> option.
436 The B<nameopt> command line switch determines how the subject and issuer
437 names are displayed. If no B<nameopt> switch is present the default "oneline"
438 format is used which is compatible with previous versions of OpenSSL.
439 Each option is described in detail below, all options can be preceded by
440 a B<-> to turn the option off. Only the first four will normally be used.
446 use the old format. This is equivalent to specifying no name options at all.
450 displays names compatible with RFC2253 equivalent to B<esc_2253>, B<esc_ctrl>,
451 B<esc_msb>, B<utf8>, B<dump_nostr>, B<dump_unknown>, B<dump_der>,
452 B<sep_comma_plus>, B<dn_rev> and B<sname>.
456 a oneline format which is more readable than RFC2253. It is equivalent to
457 specifying the B<esc_2253>, B<esc_ctrl>, B<esc_msb>, B<utf8>, B<dump_nostr>,
458 B<dump_der>, B<use_quote>, B<sep_comma_plus_space>, B<space_eq> and B<sname>
463 a multiline format. It is equivalent B<esc_ctrl>, B<esc_msb>, B<sep_multiline>,
464 B<space_eq>, B<lname> and B<align>.
468 escape the "special" characters required by RFC2253 in a field That is
469 B<,+"E<lt>E<gt>;>. Additionally B<#> is escaped at the beginning of a string
470 and a space character at the beginning or end of a string.
474 escape control characters. That is those with ASCII values less than
475 0x20 (space) and the delete (0x7f) character. They are escaped using the
476 RFC2253 \XX notation (where XX are two hex digits representing the
481 escape characters with the MSB set, that is with ASCII values larger than
486 escapes some characters by surrounding the whole string with B<"> characters,
487 without the option all escaping is done with the B<\> character.
491 convert all strings to UTF8 format first. This is required by RFC2253. If
492 you are lucky enough to have a UTF8 compatible terminal then the use
493 of this option (and B<not> setting B<esc_msb>) may result in the correct
494 display of multibyte (international) characters. Is this option is not
495 present then multibyte characters larger than 0xff will be represented
496 using the format \UXXXX for 16 bits and \WXXXXXXXX for 32 bits.
497 Also if this option is off any UTF8Strings will be converted to their
498 character form first.
502 this option does not attempt to interpret multibyte characters in any
503 way. That is their content octets are merely dumped as though one octet
504 represents each character. This is useful for diagnostic purposes but
505 will result in rather odd looking output.
509 show the type of the ASN1 character string. The type precedes the
510 field contents. For example "BMPSTRING: Hello World".
514 when this option is set any fields that need to be hexdumped will
515 be dumped using the DER encoding of the field. Otherwise just the
516 content octets will be displayed. Both options use the RFC2253
521 dump non character string types (for example OCTET STRING) if this
522 option is not set then non character string types will be displayed
523 as though each content octet represents a single character.
527 dump all fields. This option when used with B<dump_der> allows the
528 DER encoding of the structure to be unambiguously determined.
530 =item B<dump_unknown>
532 dump any field whose OID is not recognised by OpenSSL.
534 =item B<sep_comma_plus>, B<sep_comma_plus_space>, B<sep_semi_plus_space>,
537 these options determine the field separators. The first character is
538 between RDNs and the second between multiple AVAs (multiple AVAs are
539 very rare and their use is discouraged). The options ending in
540 "space" additionally place a space after the separator to make it
541 more readable. The B<sep_multiline> uses a linefeed character for
542 the RDN separator and a spaced B<+> for the AVA separator. It also
543 indents the fields by four characters. If no field separator is specified
544 then B<sep_comma_plus_space> is used by default.
548 reverse the fields of the DN. This is required by RFC2253. As a side
549 effect this also reverses the order of multiple AVAs but this is
552 =item B<nofname>, B<sname>, B<lname>, B<oid>
554 these options alter how the field name is displayed. B<nofname> does
555 not display the field at all. B<sname> uses the "short name" form
556 (CN for commonName for example). B<lname> uses the long form.
557 B<oid> represents the OID in numerical form and is useful for
562 align field values for a more readable output. Only usable with
567 places spaces round the B<=> character which follows the field
574 As well as customising the name output format, it is also possible to
575 customise the actual fields printed using the B<certopt> options when
576 the B<text> option is present. The default behaviour is to print all fields.
582 use the old format. This is equivalent to specifying no output options at all.
586 don't print header information: that is the lines saying "Certificate" and "Data".
590 don't print out the version number.
594 don't print out the serial number.
598 don't print out the signature algorithm used.
602 don't print the validity, that is the B<notBefore> and B<notAfter> fields.
606 don't print out the subject name.
610 don't print out the issuer name.
614 don't print out the public key.
618 don't give a hexadecimal dump of the certificate signature.
622 don't print out certificate trust information.
624 =item B<no_extensions>
626 don't print out any X509V3 extensions.
630 retain default extension behaviour: attempt to print out unsupported certificate extensions.
634 print an error message for unsupported certificate extensions.
638 ASN1 parse unsupported extensions.
642 hex dump unsupported extensions.
646 the value used by the B<ca> utility, equivalent to B<no_issuer>, B<no_pubkey>,
647 B<no_header>, and B<no_version>.
653 Note: in these examples the '\' means the example should be all on one
656 Display the contents of a certificate:
658 openssl x509 -in cert.pem -noout -text
660 Display the certificate serial number:
662 openssl x509 -in cert.pem -noout -serial
664 Display the certificate subject name:
666 openssl x509 -in cert.pem -noout -subject
668 Display the certificate subject name in RFC2253 form:
670 openssl x509 -in cert.pem -noout -subject -nameopt RFC2253
672 Display the certificate subject name in oneline form on a terminal
675 openssl x509 -in cert.pem -noout -subject -nameopt oneline,-esc_msb
677 Display the certificate MD5 fingerprint:
679 openssl x509 -in cert.pem -noout -fingerprint
681 Display the certificate SHA1 fingerprint:
683 openssl x509 -sha1 -in cert.pem -noout -fingerprint
685 Convert a certificate from PEM to DER format:
687 openssl x509 -in cert.pem -inform PEM -out cert.der -outform DER
689 Convert a certificate to a certificate request:
691 openssl x509 -x509toreq -in cert.pem -out req.pem -signkey key.pem
693 Convert a certificate request into a self signed certificate using
696 openssl x509 -req -in careq.pem -extfile openssl.cnf -extensions v3_ca \
697 -signkey key.pem -out cacert.pem
699 Sign a certificate request using the CA certificate above and add user
700 certificate extensions:
702 openssl x509 -req -in req.pem -extfile openssl.cnf -extensions v3_usr \
703 -CA cacert.pem -CAkey key.pem -CAcreateserial
706 Set a certificate to be trusted for SSL client use and change set its alias to
709 openssl x509 -in cert.pem -addtrust clientAuth \
710 -setalias "Steve's Class 1 CA" -out trust.pem
714 The PEM format uses the header and footer lines:
716 -----BEGIN CERTIFICATE-----
717 -----END CERTIFICATE-----
719 it will also handle files containing:
721 -----BEGIN X509 CERTIFICATE-----
722 -----END X509 CERTIFICATE-----
724 Trusted certificates have the lines
726 -----BEGIN TRUSTED CERTIFICATE-----
727 -----END TRUSTED CERTIFICATE-----
729 The conversion to UTF8 format used with the name options assumes that
730 T61Strings use the ISO8859-1 character set. This is wrong but Netscape
731 and MSIE do this as do many certificates. So although this is incorrect
732 it is more likely to display the majority of certificates correctly.
734 The B<-fingerprint> option takes the digest of the DER encoded certificate.
735 This is commonly called a "fingerprint". Because of the nature of message
736 digests the fingerprint of a certificate is unique to that certificate and
737 two certificates with the same fingerprint can be considered to be the same.
739 The Netscape fingerprint uses MD5 whereas MSIE uses SHA1.
741 The B<-email> option searches the subject name and the subject alternative
742 name extension. Only unique email addresses will be printed out: it will
743 not print the same address more than once.
745 =head1 CERTIFICATE EXTENSIONS
747 The B<-purpose> option checks the certificate extensions and determines
748 what the certificate can be used for. The actual checks done are rather
749 complex and include various hacks and workarounds to handle broken
750 certificates and software.
752 The same code is used when verifying untrusted certificates in chains
753 so this section is useful if a chain is rejected by the verify code.
755 The basicConstraints extension CA flag is used to determine whether the
756 certificate can be used as a CA. If the CA flag is true then it is a CA,
757 if the CA flag is false then it is not a CA. B<All> CAs should have the
760 If the basicConstraints extension is absent then the certificate is
761 considered to be a "possible CA" other extensions are checked according
762 to the intended use of the certificate. A warning is given in this case
763 because the certificate should really not be regarded as a CA: however
764 it is allowed to be a CA to work around some broken software.
766 If the certificate is a V1 certificate (and thus has no extensions) and
767 it is self signed it is also assumed to be a CA but a warning is again
768 given: this is to work around the problem of Verisign roots which are V1
769 self signed certificates.
771 If the keyUsage extension is present then additional restraints are
772 made on the uses of the certificate. A CA certificate B<must> have the
773 keyCertSign bit set if the keyUsage extension is present.
775 The extended key usage extension places additional restrictions on the
776 certificate uses. If this extension is present (whether critical or not)
777 the key can only be used for the purposes specified.
779 A complete description of each test is given below. The comments about
780 basicConstraints and keyUsage and V1 certificates above apply to B<all>
788 The extended key usage extension must be absent or include the "web client
789 authentication" OID. keyUsage must be absent or it must have the
790 digitalSignature bit set. Netscape certificate type must be absent or it must
791 have the SSL client bit set.
793 =item B<SSL Client CA>
795 The extended key usage extension must be absent or include the "web client
796 authentication" OID. Netscape certificate type must be absent or it must have
797 the SSL CA bit set: this is used as a work around if the basicConstraints
802 The extended key usage extension must be absent or include the "web server
803 authentication" and/or one of the SGC OIDs. keyUsage must be absent or it
804 must have the digitalSignature, the keyEncipherment set or both bits set.
805 Netscape certificate type must be absent or have the SSL server bit set.
807 =item B<SSL Server CA>
809 The extended key usage extension must be absent or include the "web server
810 authentication" and/or one of the SGC OIDs. Netscape certificate type must
811 be absent or the SSL CA bit must be set: this is used as a work around if the
812 basicConstraints extension is absent.
814 =item B<Netscape SSL Server>
816 For Netscape SSL clients to connect to an SSL server it must have the
817 keyEncipherment bit set if the keyUsage extension is present. This isn't
818 always valid because some cipher suites use the key for digital signing.
819 Otherwise it is the same as a normal SSL server.
821 =item B<Common S/MIME Client Tests>
823 The extended key usage extension must be absent or include the "email
824 protection" OID. Netscape certificate type must be absent or should have the
825 S/MIME bit set. If the S/MIME bit is not set in netscape certificate type
826 then the SSL client bit is tolerated as an alternative but a warning is shown:
827 this is because some Verisign certificates don't set the S/MIME bit.
829 =item B<S/MIME Signing>
831 In addition to the common S/MIME client tests the digitalSignature bit must
832 be set if the keyUsage extension is present.
834 =item B<S/MIME Encryption>
836 In addition to the common S/MIME tests the keyEncipherment bit must be set
837 if the keyUsage extension is present.
841 The extended key usage extension must be absent or include the "email
842 protection" OID. Netscape certificate type must be absent or must have the
843 S/MIME CA bit set: this is used as a work around if the basicConstraints
848 The keyUsage extension must be absent or it must have the CRL signing bit
851 =item B<CRL Signing CA>
853 The normal CA tests apply. Except in this case the basicConstraints extension
860 Extensions in certificates are not transferred to certificate requests and
863 It is possible to produce invalid certificates or requests by specifying the
864 wrong private key or using inconsistent options in some cases: these should
867 There should be options to explicitly set such things as start and end
868 dates rather than an offset from the current time.
870 The code to implement the verify behaviour described in the B<TRUST SETTINGS>
871 is currently being developed. It thus describes the intended behaviour rather
872 than the current behaviour. It is hoped that it will represent reality in
873 OpenSSL 0.9.5 and later.
877 L<req(1)|req(1)>, L<ca(1)|ca(1)>, L<genrsa(1)|genrsa(1)>,
878 L<gendsa(1)|gendsa(1)>, L<verify(1)|verify(1)>,
879 L<x509v3_config(5)|x509v3_config(5)>
883 Before OpenSSL 0.9.8, the default digest for RSA keys was MD5.
885 The hash algorithm used in the B<-subject_hash> and B<-issuer_hash> options
886 before OpenSSL 1.0.0 was based on the deprecated MD5 algorithm and the encoding
887 of the distinguished name. In OpenSSL 1.0.0 and later it is based on a
888 canonical version of the DN using SHA1. This means that any directories using
889 the old form must have their links rebuilt using B<c_rehash> or similar.