6 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>]
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
83 Print out a usage message.
85 =item B<-inform DER|PEM|NET>
87 This specifies the input format normally the command will expect an X509
88 certificate but this can change if other options such as B<-req> are
89 present. The DER format is the DER encoding of the certificate and PEM
90 is the base64 encoding of the DER encoding with header and footer lines
91 added. The NET option is an obscure Netscape server format that is now
94 =item B<-outform DER|PEM|NET>
96 This specifies the output format, the options have the same meaning as the
101 This specifies the input filename to read a certificate from or standard input
102 if this option is not specified.
104 =item B<-out filename>
106 This specifies the output filename to write to or standard output by
112 This affects any signing or display option that uses a message
113 digest, such as the B<-fingerprint>, B<-signkey> and B<-CA> options.
114 Any digest supported by the OpenSSL B<dgst> command can be used.
115 If not specified then SHA1 is used with B<-fingerprint> or
116 the default digest for the signing algorithm is used, typically SHA256.
120 specifying an engine (by its unique B<id> string) will cause B<x509>
121 to attempt to obtain a functional reference to the specified engine,
122 thus initialising it if needed. The engine will then be set as the default
123 for all available algorithms.
127 =head2 DISPLAY OPTIONS
129 Note: the B<-alias> and B<-purpose> options are also display options
130 but are described in the B<TRUST SETTINGS> section.
136 prints out the certificate in text form. Full details are output including the
137 public key, signature algorithms, issuer and subject names, serial number
138 any extensions present and any trust settings.
140 =item B<-certopt option>
142 customise the output format used with B<-text>. The B<option> argument can be
143 a single option or multiple options separated by commas. The B<-certopt> switch
144 may be also be used more than once to set multiple options. See the B<TEXT OPTIONS>
145 section for more information.
149 this option prevents output of the encoded version of the request.
153 outputs the certificate's SubjectPublicKeyInfo block in PEM format.
157 this option prints out the value of the modulus of the public key
158 contained in the certificate.
162 outputs the certificate serial number.
164 =item B<-subject_hash>
166 outputs the "hash" of the certificate subject name. This is used in OpenSSL to
167 form an index to allow certificates in a directory to be looked up by subject
170 =item B<-issuer_hash>
172 outputs the "hash" of the certificate issuer name.
176 outputs the OCSP hash values for the subject name and public key.
180 synonym for "-subject_hash" for backward compatibility reasons.
182 =item B<-subject_hash_old>
184 outputs the "hash" of the certificate subject name using the older algorithm
185 as used by OpenSSL versions before 1.0.0.
187 =item B<-issuer_hash_old>
189 outputs the "hash" of the certificate issuer name using the older algorithm
190 as used by OpenSSL versions before 1.0.0.
194 outputs the subject name.
198 outputs the issuer name.
200 =item B<-nameopt option>
202 option which determines how the subject or issuer names are displayed. The
203 B<option> argument can be a single option or multiple options separated by
204 commas. Alternatively the B<-nameopt> switch may be used more than once to
205 set multiple options. See the B<NAME OPTIONS> section for more information.
209 outputs the email address(es) if any.
213 outputs the OCSP responder address(es) if any.
217 prints out the start date of the certificate, that is the notBefore date.
221 prints out the expiry date of the certificate, that is the notAfter date.
225 prints out the start and expiry dates of a certificate.
227 =item B<-checkend arg>
229 checks if the certificate expires within the next B<arg> seconds and exits
230 non-zero if yes it will expire or zero if not.
232 =item B<-fingerprint>
234 prints out the digest of the DER encoded version of the whole certificate
235 (see digest options).
239 this outputs the certificate in the form of a C source file.
243 =head2 TRUST SETTINGS
245 A B<trusted certificate> is an ordinary certificate which has several
246 additional pieces of information attached to it such as the permitted
247 and prohibited uses of the certificate and an "alias".
249 Normally when a certificate is being verified at least one certificate
250 must be "trusted". By default a trusted certificate must be stored
251 locally and must be a root CA: any certificate chain ending in this CA
252 is then usable for any purpose.
254 Trust settings currently are only used with a root CA. They allow a finer
255 control over the purposes the root CA can be used for. For example a CA
256 may be trusted for SSL client but not SSL server use.
258 See the description of the B<verify> utility for more information on the
259 meaning of trust settings.
261 Future versions of OpenSSL will recognize trust settings on any
262 certificate: not just root CAs.
269 this causes B<x509> to output a B<trusted> certificate. An ordinary
270 or trusted certificate can be input but by default an ordinary
271 certificate is output and any trust settings are discarded. With the
272 B<-trustout> option a trusted certificate is output. A trusted
273 certificate is automatically output if any trust settings are modified.
275 =item B<-setalias arg>
277 sets the alias of the certificate. This will allow the certificate
278 to be referred to using a nickname for example "Steve's Certificate".
282 outputs the certificate alias, if any.
286 clears all the permitted or trusted uses of the certificate.
290 clears all the prohibited or rejected uses of the certificate.
292 =item B<-addtrust arg>
294 adds a trusted certificate use.
295 Any object name can be used here but currently only B<clientAuth> (SSL client
296 use), B<serverAuth> (SSL server use), B<emailProtection> (S/MIME email) and
297 B<anyExtendedKeyUsage> are used.
298 As of OpenSSL 1.1.0, the last of these blocks all purposes when rejected or
299 enables all purposes when trusted.
300 Other OpenSSL applications may define additional uses.
302 =item B<-addreject arg>
304 adds a prohibited use. It accepts the same values as the B<-addtrust>
309 this option performs tests on the certificate extensions and outputs
310 the results. For a more complete description see the B<CERTIFICATE
315 =head2 SIGNING OPTIONS
317 The B<x509> utility can be used to sign certificates and requests: it
318 can thus behave like a "mini CA".
322 =item B<-signkey filename>
324 this option causes the input file to be self signed using the supplied
327 If the input file is a certificate it sets the issuer name to the
328 subject name (i.e. makes it self signed) changes the public key to the
329 supplied value and changes the start and end dates. The start date is
330 set to the current time and the end date is set to a value determined
331 by the B<-days> option. Any certificate extensions are retained unless
332 the B<-clrext> option is supplied; this includes, for example, any existing
333 key identifier extensions.
335 If the input is a certificate request then a self signed certificate
336 is created using the supplied private key using the subject name in
341 the key password source. For more information about the format of B<arg>
342 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)>.
346 delete any extensions from a certificate. This option is used when a
347 certificate is being created from another certificate (for example with
348 the B<-signkey> or the B<-CA> options). Normally all extensions are
351 =item B<-keyform PEM|DER>
353 specifies the format (DER or PEM) of the private key file used in the
358 specifies the number of days to make a certificate valid for. The default
363 converts a certificate into a certificate request. The B<-signkey> option
364 is used to pass the required private key.
368 by default a certificate is expected on input. With this option a
369 certificate request is expected instead.
371 =item B<-set_serial n>
373 specifies the serial number to use. This option can be used with either
374 the B<-signkey> or B<-CA> options. If used in conjunction with the B<-CA>
375 option the serial number file (as specified by the B<-CAserial> or
376 B<-CAcreateserial> options) is not used.
378 The serial number can be decimal or hex (if preceded by B<0x>).
380 =item B<-CA filename>
382 specifies the CA certificate to be used for signing. When this option is
383 present B<x509> behaves like a "mini CA". The input file is signed by this
384 CA using this option: that is its issuer name is set to the subject name
385 of the CA and it is digitally signed using the CAs private key.
387 This option is normally combined with the B<-req> option. Without the
388 B<-req> option the input is a certificate which must be self signed.
390 =item B<-CAkey filename>
392 sets the CA private key to sign a certificate with. If this option is
393 not specified then it is assumed that the CA private key is present in
394 the CA certificate file.
396 =item B<-CAserial filename>
398 sets the CA serial number file to use.
400 When the B<-CA> option is used to sign a certificate it uses a serial
401 number specified in a file. This file consist of one line containing
402 an even number of hex digits with the serial number to use. After each
403 use the serial number is incremented and written out to the file again.
405 The default filename consists of the CA certificate file base name with
406 ".srl" appended. For example if the CA certificate file is called
407 "mycacert.pem" it expects to find a serial number file called "mycacert.srl".
409 =item B<-CAcreateserial>
411 with this option the CA serial number file is created if it does not exist:
412 it will contain the serial number "02" and the certificate being signed will
413 have the 1 as its serial number. If the B<-CA> option is specified
414 and the serial number file does not exist a random number is generated;
415 this is the recommended practice.
417 =item B<-extfile filename>
419 file containing certificate extensions to use. If not specified then
420 no extensions are added to the certificate.
422 =item B<-extensions section>
424 the section to add certificate extensions from. If this option is not
425 specified then the extensions should either be contained in the unnamed
426 (default) section or the default section should contain a variable called
427 "extensions" which contains the section to use. See the
428 L<x509v3_config(5)> manual page for details of the
429 extension section format.
431 =item B<-force_pubkey key>
433 when a certificate is created set its public key to B<key> instead of the
434 key in the certificate or certificate request. This option is useful for
435 creating certificates where the algorithm can't normally sign requests, for
438 The format or B<key> can be specified using the B<-keyform> option.
444 The B<nameopt> command line switch determines how the subject and issuer
445 names are displayed. If no B<nameopt> switch is present the default "oneline"
446 format is used which is compatible with previous versions of OpenSSL.
447 Each option is described in detail below, all options can be preceded by
448 a B<-> to turn the option off. Only the first four will normally be used.
458 displays names compatible with RFC2253 equivalent to B<esc_2253>, B<esc_ctrl>,
459 B<esc_msb>, B<utf8>, B<dump_nostr>, B<dump_unknown>, B<dump_der>,
460 B<sep_comma_plus>, B<dn_rev> and B<sname>.
464 a oneline format which is more readable than RFC2253. It is equivalent to
465 specifying the B<esc_2253>, B<esc_ctrl>, B<esc_msb>, B<utf8>, B<dump_nostr>,
466 B<dump_der>, B<use_quote>, B<sep_comma_plus_space>, B<space_eq> and B<sname>
467 options. This is the I<default> of no name options are given explicitly.
471 a multiline format. It is equivalent B<esc_ctrl>, B<esc_msb>, B<sep_multiline>,
472 B<space_eq>, B<lname> and B<align>.
476 escape the "special" characters required by RFC2253 in a field That is
477 B<,+"E<lt>E<gt>;>. Additionally B<#> is escaped at the beginning of a string
478 and a space character at the beginning or end of a string.
482 escape control characters. That is those with ASCII values less than
483 0x20 (space) and the delete (0x7f) character. They are escaped using the
484 RFC2253 \XX notation (where XX are two hex digits representing the
489 escape characters with the MSB set, that is with ASCII values larger than
494 escapes some characters by surrounding the whole string with B<"> characters,
495 without the option all escaping is done with the B<\> character.
499 convert all strings to UTF8 format first. This is required by RFC2253. If
500 you are lucky enough to have a UTF8 compatible terminal then the use
501 of this option (and B<not> setting B<esc_msb>) may result in the correct
502 display of multibyte (international) characters. Is this option is not
503 present then multibyte characters larger than 0xff will be represented
504 using the format \UXXXX for 16 bits and \WXXXXXXXX for 32 bits.
505 Also if this option is off any UTF8Strings will be converted to their
506 character form first.
510 this option does not attempt to interpret multibyte characters in any
511 way. That is their content octets are merely dumped as though one octet
512 represents each character. This is useful for diagnostic purposes but
513 will result in rather odd looking output.
517 show the type of the ASN1 character string. The type precedes the
518 field contents. For example "BMPSTRING: Hello World".
522 when this option is set any fields that need to be hexdumped will
523 be dumped using the DER encoding of the field. Otherwise just the
524 content octets will be displayed. Both options use the RFC2253
529 dump non character string types (for example OCTET STRING) if this
530 option is not set then non character string types will be displayed
531 as though each content octet represents a single character.
535 dump all fields. This option when used with B<dump_der> allows the
536 DER encoding of the structure to be unambiguously determined.
538 =item B<dump_unknown>
540 dump any field whose OID is not recognised by OpenSSL.
542 =item B<sep_comma_plus>, B<sep_comma_plus_space>, B<sep_semi_plus_space>,
545 these options determine the field separators. The first character is
546 between RDNs and the second between multiple AVAs (multiple AVAs are
547 very rare and their use is discouraged). The options ending in
548 "space" additionally place a space after the separator to make it
549 more readable. The B<sep_multiline> uses a linefeed character for
550 the RDN separator and a spaced B<+> for the AVA separator. It also
551 indents the fields by four characters. If no field separator is specified
552 then B<sep_comma_plus_space> is used by default.
556 reverse the fields of the DN. This is required by RFC2253. As a side
557 effect this also reverses the order of multiple AVAs but this is
560 =item B<nofname>, B<sname>, B<lname>, B<oid>
562 these options alter how the field name is displayed. B<nofname> does
563 not display the field at all. B<sname> uses the "short name" form
564 (CN for commonName for example). B<lname> uses the long form.
565 B<oid> represents the OID in numerical form and is useful for
570 align field values for a more readable output. Only usable with
575 places spaces round the B<=> character which follows the field
582 As well as customising the name output format, it is also possible to
583 customise the actual fields printed using the B<certopt> options when
584 the B<text> option is present. The default behaviour is to print all fields.
590 use the old format. This is equivalent to specifying no output options at all.
594 don't print header information: that is the lines saying "Certificate" and "Data".
598 don't print out the version number.
602 don't print out the serial number.
606 don't print out the signature algorithm used.
610 don't print the validity, that is the B<notBefore> and B<notAfter> fields.
614 don't print out the subject name.
618 don't print out the issuer name.
622 don't print out the public key.
626 don't give a hexadecimal dump of the certificate signature.
630 don't print out certificate trust information.
632 =item B<no_extensions>
634 don't print out any X509V3 extensions.
638 retain default extension behaviour: attempt to print out unsupported certificate extensions.
642 print an error message for unsupported certificate extensions.
646 ASN1 parse unsupported extensions.
650 hex dump unsupported extensions.
654 the value used by the B<ca> utility, equivalent to B<no_issuer>, B<no_pubkey>, B<no_header>,
655 B<no_version>, B<no_sigdump> and B<no_signame>.
661 Note: in these examples the '\' means the example should be all on one
664 Display the contents of a certificate:
666 openssl x509 -in cert.pem -noout -text
668 Display the certificate serial number:
670 openssl x509 -in cert.pem -noout -serial
672 Display the certificate subject name:
674 openssl x509 -in cert.pem -noout -subject
676 Display the certificate subject name in RFC2253 form:
678 openssl x509 -in cert.pem -noout -subject -nameopt RFC2253
680 Display the certificate subject name in oneline form on a terminal
683 openssl x509 -in cert.pem -noout -subject -nameopt oneline,-esc_msb
685 Display the certificate MD5 fingerprint:
687 openssl x509 -in cert.pem -noout -fingerprint
689 Display the certificate SHA1 fingerprint:
691 openssl x509 -sha1 -in cert.pem -noout -fingerprint
693 Convert a certificate from PEM to DER format:
695 openssl x509 -in cert.pem -inform PEM -out cert.der -outform DER
697 Convert a certificate to a certificate request:
699 openssl x509 -x509toreq -in cert.pem -out req.pem -signkey key.pem
701 Convert a certificate request into a self signed certificate using
704 openssl x509 -req -in careq.pem -extfile openssl.cnf -extensions v3_ca \
705 -signkey key.pem -out cacert.pem
707 Sign a certificate request using the CA certificate above and add user
708 certificate extensions:
710 openssl x509 -req -in req.pem -extfile openssl.cnf -extensions v3_usr \
711 -CA cacert.pem -CAkey key.pem -CAcreateserial
714 Set a certificate to be trusted for SSL client use and change set its alias to
717 openssl x509 -in cert.pem -addtrust clientAuth \
718 -setalias "Steve's Class 1 CA" -out trust.pem
722 The PEM format uses the header and footer lines:
724 -----BEGIN CERTIFICATE-----
725 -----END CERTIFICATE-----
727 it will also handle files containing:
729 -----BEGIN X509 CERTIFICATE-----
730 -----END X509 CERTIFICATE-----
732 Trusted certificates have the lines
734 -----BEGIN TRUSTED CERTIFICATE-----
735 -----END TRUSTED CERTIFICATE-----
737 The conversion to UTF8 format used with the name options assumes that
738 T61Strings use the ISO8859-1 character set. This is wrong but Netscape
739 and MSIE do this as do many certificates. So although this is incorrect
740 it is more likely to display the majority of certificates correctly.
742 The B<-fingerprint> option takes the digest of the DER encoded certificate.
743 This is commonly called a "fingerprint". Because of the nature of message
744 digests the fingerprint of a certificate is unique to that certificate and
745 two certificates with the same fingerprint can be considered to be the same.
747 The Netscape fingerprint uses MD5 whereas MSIE uses SHA1.
749 The B<-email> option searches the subject name and the subject alternative
750 name extension. Only unique email addresses will be printed out: it will
751 not print the same address more than once.
753 =head1 CERTIFICATE EXTENSIONS
755 The B<-purpose> option checks the certificate extensions and determines
756 what the certificate can be used for. The actual checks done are rather
757 complex and include various hacks and workarounds to handle broken
758 certificates and software.
760 The same code is used when verifying untrusted certificates in chains
761 so this section is useful if a chain is rejected by the verify code.
763 The basicConstraints extension CA flag is used to determine whether the
764 certificate can be used as a CA. If the CA flag is true then it is a CA,
765 if the CA flag is false then it is not a CA. B<All> CAs should have the
768 If the basicConstraints extension is absent then the certificate is
769 considered to be a "possible CA" other extensions are checked according
770 to the intended use of the certificate. A warning is given in this case
771 because the certificate should really not be regarded as a CA: however
772 it is allowed to be a CA to work around some broken software.
774 If the certificate is a V1 certificate (and thus has no extensions) and
775 it is self signed it is also assumed to be a CA but a warning is again
776 given: this is to work around the problem of Verisign roots which are V1
777 self signed certificates.
779 If the keyUsage extension is present then additional restraints are
780 made on the uses of the certificate. A CA certificate B<must> have the
781 keyCertSign bit set if the keyUsage extension is present.
783 The extended key usage extension places additional restrictions on the
784 certificate uses. If this extension is present (whether critical or not)
785 the key can only be used for the purposes specified.
787 A complete description of each test is given below. The comments about
788 basicConstraints and keyUsage and V1 certificates above apply to B<all>
796 The extended key usage extension must be absent or include the "web client
797 authentication" OID. keyUsage must be absent or it must have the
798 digitalSignature bit set. Netscape certificate type must be absent or it must
799 have the SSL client bit set.
801 =item B<SSL Client CA>
803 The extended key usage extension must be absent or include the "web client
804 authentication" OID. Netscape certificate type must be absent or it must have
805 the SSL CA bit set: this is used as a work around if the basicConstraints
810 The extended key usage extension must be absent or include the "web server
811 authentication" and/or one of the SGC OIDs. keyUsage must be absent or it
812 must have the digitalSignature, the keyEncipherment set or both bits set.
813 Netscape certificate type must be absent or have the SSL server bit set.
815 =item B<SSL Server CA>
817 The extended key usage extension must be absent or include the "web server
818 authentication" and/or one of the SGC OIDs. Netscape certificate type must
819 be absent or the SSL CA bit must be set: this is used as a work around if the
820 basicConstraints extension is absent.
822 =item B<Netscape SSL Server>
824 For Netscape SSL clients to connect to an SSL server it must have the
825 keyEncipherment bit set if the keyUsage extension is present. This isn't
826 always valid because some cipher suites use the key for digital signing.
827 Otherwise it is the same as a normal SSL server.
829 =item B<Common S/MIME Client Tests>
831 The extended key usage extension must be absent or include the "email
832 protection" OID. Netscape certificate type must be absent or should have the
833 S/MIME bit set. If the S/MIME bit is not set in netscape certificate type
834 then the SSL client bit is tolerated as an alternative but a warning is shown:
835 this is because some Verisign certificates don't set the S/MIME bit.
837 =item B<S/MIME Signing>
839 In addition to the common S/MIME client tests the digitalSignature bit must
840 be set if the keyUsage extension is present.
842 =item B<S/MIME Encryption>
844 In addition to the common S/MIME tests the keyEncipherment bit must be set
845 if the keyUsage extension is present.
849 The extended key usage extension must be absent or include the "email
850 protection" OID. Netscape certificate type must be absent or must have the
851 S/MIME CA bit set: this is used as a work around if the basicConstraints
856 The keyUsage extension must be absent or it must have the CRL signing bit
859 =item B<CRL Signing CA>
861 The normal CA tests apply. Except in this case the basicConstraints extension
868 Extensions in certificates are not transferred to certificate requests and
871 It is possible to produce invalid certificates or requests by specifying the
872 wrong private key or using inconsistent options in some cases: these should
875 There should be options to explicitly set such things as start and end
876 dates rather than an offset from the current time.
880 L<req(1)>, L<ca(1)>, L<genrsa(1)>,
881 L<gendsa(1)>, L<verify(1)>,
886 The hash algorithm used in the B<-subject_hash> and B<-issuer_hash> options
887 before OpenSSL 1.0.0 was based on the deprecated MD5 algorithm and the encoding
888 of the distinguished name. In OpenSSL 1.0.0 and later it is based on a
889 canonical version of the DN using SHA1. This means that any directories using
890 the old form must have their links rebuilt using B<c_rehash> or similar.