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 the "special" characters required by RFC2254 in a field. That is
483 the B<NUL> character as well as and B<()*>.
487 escape control characters. That is those with ASCII values less than
488 0x20 (space) and the delete (0x7f) character. They are escaped using the
489 RFC2253 \XX notation (where XX are two hex digits representing the
494 escape characters with the MSB set, that is with ASCII values larger than
499 escapes some characters by surrounding the whole string with B<"> characters,
500 without the option all escaping is done with the B<\> character.
504 convert all strings to UTF8 format first. This is required by RFC2253. If
505 you are lucky enough to have a UTF8 compatible terminal then the use
506 of this option (and B<not> setting B<esc_msb>) may result in the correct
507 display of multibyte (international) characters. Is this option is not
508 present then multibyte characters larger than 0xff will be represented
509 using the format \UXXXX for 16 bits and \WXXXXXXXX for 32 bits.
510 Also if this option is off any UTF8Strings will be converted to their
511 character form first.
515 this option does not attempt to interpret multibyte characters in any
516 way. That is their content octets are merely dumped as though one octet
517 represents each character. This is useful for diagnostic purposes but
518 will result in rather odd looking output.
522 show the type of the ASN1 character string. The type precedes the
523 field contents. For example "BMPSTRING: Hello World".
527 when this option is set any fields that need to be hexdumped will
528 be dumped using the DER encoding of the field. Otherwise just the
529 content octets will be displayed. Both options use the RFC2253
534 dump non character string types (for example OCTET STRING) if this
535 option is not set then non character string types will be displayed
536 as though each content octet represents a single character.
540 dump all fields. This option when used with B<dump_der> allows the
541 DER encoding of the structure to be unambiguously determined.
543 =item B<dump_unknown>
545 dump any field whose OID is not recognised by OpenSSL.
547 =item B<sep_comma_plus>, B<sep_comma_plus_space>, B<sep_semi_plus_space>,
550 these options determine the field separators. The first character is
551 between RDNs and the second between multiple AVAs (multiple AVAs are
552 very rare and their use is discouraged). The options ending in
553 "space" additionally place a space after the separator to make it
554 more readable. The B<sep_multiline> uses a linefeed character for
555 the RDN separator and a spaced B<+> for the AVA separator. It also
556 indents the fields by four characters. If no field separator is specified
557 then B<sep_comma_plus_space> is used by default.
561 reverse the fields of the DN. This is required by RFC2253. As a side
562 effect this also reverses the order of multiple AVAs but this is
565 =item B<nofname>, B<sname>, B<lname>, B<oid>
567 these options alter how the field name is displayed. B<nofname> does
568 not display the field at all. B<sname> uses the "short name" form
569 (CN for commonName for example). B<lname> uses the long form.
570 B<oid> represents the OID in numerical form and is useful for
575 align field values for a more readable output. Only usable with
580 places spaces round the B<=> character which follows the field
587 As well as customising the name output format, it is also possible to
588 customise the actual fields printed using the B<certopt> options when
589 the B<text> option is present. The default behaviour is to print all fields.
595 use the old format. This is equivalent to specifying no output options at all.
599 don't print header information: that is the lines saying "Certificate" and "Data".
603 don't print out the version number.
607 don't print out the serial number.
611 don't print out the signature algorithm used.
615 don't print the validity, that is the B<notBefore> and B<notAfter> fields.
619 don't print out the subject name.
623 don't print out the issuer name.
627 don't print out the public key.
631 don't give a hexadecimal dump of the certificate signature.
635 don't print out certificate trust information.
637 =item B<no_extensions>
639 don't print out any X509V3 extensions.
643 retain default extension behaviour: attempt to print out unsupported certificate extensions.
647 print an error message for unsupported certificate extensions.
651 ASN1 parse unsupported extensions.
655 hex dump unsupported extensions.
659 the value used by the B<ca> utility, equivalent to B<no_issuer>, B<no_pubkey>, B<no_header>,
660 B<no_version>, B<no_sigdump> and B<no_signame>.
666 Note: in these examples the '\' means the example should be all on one
669 Display the contents of a certificate:
671 openssl x509 -in cert.pem -noout -text
673 Display the certificate serial number:
675 openssl x509 -in cert.pem -noout -serial
677 Display the certificate subject name:
679 openssl x509 -in cert.pem -noout -subject
681 Display the certificate subject name in RFC2253 form:
683 openssl x509 -in cert.pem -noout -subject -nameopt RFC2253
685 Display the certificate subject name in oneline form on a terminal
688 openssl x509 -in cert.pem -noout -subject -nameopt oneline,-esc_msb
690 Display the certificate MD5 fingerprint:
692 openssl x509 -in cert.pem -noout -fingerprint
694 Display the certificate SHA1 fingerprint:
696 openssl x509 -sha1 -in cert.pem -noout -fingerprint
698 Convert a certificate from PEM to DER format:
700 openssl x509 -in cert.pem -inform PEM -out cert.der -outform DER
702 Convert a certificate to a certificate request:
704 openssl x509 -x509toreq -in cert.pem -out req.pem -signkey key.pem
706 Convert a certificate request into a self signed certificate using
709 openssl x509 -req -in careq.pem -extfile openssl.cnf -extensions v3_ca \
710 -signkey key.pem -out cacert.pem
712 Sign a certificate request using the CA certificate above and add user
713 certificate extensions:
715 openssl x509 -req -in req.pem -extfile openssl.cnf -extensions v3_usr \
716 -CA cacert.pem -CAkey key.pem -CAcreateserial
719 Set a certificate to be trusted for SSL client use and change set its alias to
722 openssl x509 -in cert.pem -addtrust clientAuth \
723 -setalias "Steve's Class 1 CA" -out trust.pem
727 The PEM format uses the header and footer lines:
729 -----BEGIN CERTIFICATE-----
730 -----END CERTIFICATE-----
732 it will also handle files containing:
734 -----BEGIN X509 CERTIFICATE-----
735 -----END X509 CERTIFICATE-----
737 Trusted certificates have the lines
739 -----BEGIN TRUSTED CERTIFICATE-----
740 -----END TRUSTED CERTIFICATE-----
742 The conversion to UTF8 format used with the name options assumes that
743 T61Strings use the ISO8859-1 character set. This is wrong but Netscape
744 and MSIE do this as do many certificates. So although this is incorrect
745 it is more likely to display the majority of certificates correctly.
747 The B<-fingerprint> option takes the digest of the DER encoded certificate.
748 This is commonly called a "fingerprint". Because of the nature of message
749 digests the fingerprint of a certificate is unique to that certificate and
750 two certificates with the same fingerprint can be considered to be the same.
752 The Netscape fingerprint uses MD5 whereas MSIE uses SHA1.
754 The B<-email> option searches the subject name and the subject alternative
755 name extension. Only unique email addresses will be printed out: it will
756 not print the same address more than once.
758 =head1 CERTIFICATE EXTENSIONS
760 The B<-purpose> option checks the certificate extensions and determines
761 what the certificate can be used for. The actual checks done are rather
762 complex and include various hacks and workarounds to handle broken
763 certificates and software.
765 The same code is used when verifying untrusted certificates in chains
766 so this section is useful if a chain is rejected by the verify code.
768 The basicConstraints extension CA flag is used to determine whether the
769 certificate can be used as a CA. If the CA flag is true then it is a CA,
770 if the CA flag is false then it is not a CA. B<All> CAs should have the
773 If the basicConstraints extension is absent then the certificate is
774 considered to be a "possible CA" other extensions are checked according
775 to the intended use of the certificate. A warning is given in this case
776 because the certificate should really not be regarded as a CA: however
777 it is allowed to be a CA to work around some broken software.
779 If the certificate is a V1 certificate (and thus has no extensions) and
780 it is self signed it is also assumed to be a CA but a warning is again
781 given: this is to work around the problem of Verisign roots which are V1
782 self signed certificates.
784 If the keyUsage extension is present then additional restraints are
785 made on the uses of the certificate. A CA certificate B<must> have the
786 keyCertSign bit set if the keyUsage extension is present.
788 The extended key usage extension places additional restrictions on the
789 certificate uses. If this extension is present (whether critical or not)
790 the key can only be used for the purposes specified.
792 A complete description of each test is given below. The comments about
793 basicConstraints and keyUsage and V1 certificates above apply to B<all>
801 The extended key usage extension must be absent or include the "web client
802 authentication" OID. keyUsage must be absent or it must have the
803 digitalSignature bit set. Netscape certificate type must be absent or it must
804 have the SSL client bit set.
806 =item B<SSL Client CA>
808 The extended key usage extension must be absent or include the "web client
809 authentication" OID. Netscape certificate type must be absent or it must have
810 the SSL CA bit set: this is used as a work around if the basicConstraints
815 The extended key usage extension must be absent or include the "web server
816 authentication" and/or one of the SGC OIDs. keyUsage must be absent or it
817 must have the digitalSignature, the keyEncipherment set or both bits set.
818 Netscape certificate type must be absent or have the SSL server bit set.
820 =item B<SSL Server CA>
822 The extended key usage extension must be absent or include the "web server
823 authentication" and/or one of the SGC OIDs. Netscape certificate type must
824 be absent or the SSL CA bit must be set: this is used as a work around if the
825 basicConstraints extension is absent.
827 =item B<Netscape SSL Server>
829 For Netscape SSL clients to connect to an SSL server it must have the
830 keyEncipherment bit set if the keyUsage extension is present. This isn't
831 always valid because some cipher suites use the key for digital signing.
832 Otherwise it is the same as a normal SSL server.
834 =item B<Common S/MIME Client Tests>
836 The extended key usage extension must be absent or include the "email
837 protection" OID. Netscape certificate type must be absent or should have the
838 S/MIME bit set. If the S/MIME bit is not set in netscape certificate type
839 then the SSL client bit is tolerated as an alternative but a warning is shown:
840 this is because some Verisign certificates don't set the S/MIME bit.
842 =item B<S/MIME Signing>
844 In addition to the common S/MIME client tests the digitalSignature bit must
845 be set if the keyUsage extension is present.
847 =item B<S/MIME Encryption>
849 In addition to the common S/MIME tests the keyEncipherment bit must be set
850 if the keyUsage extension is present.
854 The extended key usage extension must be absent or include the "email
855 protection" OID. Netscape certificate type must be absent or must have the
856 S/MIME CA bit set: this is used as a work around if the basicConstraints
861 The keyUsage extension must be absent or it must have the CRL signing bit
864 =item B<CRL Signing CA>
866 The normal CA tests apply. Except in this case the basicConstraints extension
873 Extensions in certificates are not transferred to certificate requests and
876 It is possible to produce invalid certificates or requests by specifying the
877 wrong private key or using inconsistent options in some cases: these should
880 There should be options to explicitly set such things as start and end
881 dates rather than an offset from the current time.
885 L<req(1)>, L<ca(1)>, L<genrsa(1)>,
886 L<gendsa(1)>, L<verify(1)>,
891 The hash algorithm used in the B<-subject_hash> and B<-issuer_hash> options
892 before OpenSSL 1.0.0 was based on the deprecated MD5 algorithm and the encoding
893 of the distinguished name. In OpenSSL 1.0.0 and later it is based on a
894 canonical version of the DN using SHA1. This means that any directories using
895 the old form must have their links rebuilt using B<c_rehash> or similar.