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.
116 Note that if a DSA key is used for signing, then this flag is ignored
121 specifying an engine (by its unique B<id> string) will cause B<x509>
122 to attempt to obtain a functional reference to the specified engine,
123 thus initialising it if needed. The engine will then be set as the default
124 for all available algorithms.
128 =head2 DISPLAY OPTIONS
130 Note: the B<-alias> and B<-purpose> options are also display options
131 but are described in the B<TRUST SETTINGS> section.
137 prints out the certificate in text form. Full details are output including the
138 public key, signature algorithms, issuer and subject names, serial number
139 any extensions present and any trust settings.
141 =item B<-certopt option>
143 customise the output format used with B<-text>. The B<option> argument can be
144 a single option or multiple options separated by commas. The B<-certopt> switch
145 may be also be used more than once to set multiple options. See the B<TEXT OPTIONS>
146 section for more information.
150 this option prevents output of the encoded version of the request.
154 outputs the the certificate's SubjectPublicKeyInfo block in PEM format.
158 this option prints out the value of the modulus of the public key
159 contained in the certificate.
163 outputs the certificate serial number.
165 =item B<-subject_hash>
167 outputs the "hash" of the certificate subject name. This is used in OpenSSL to
168 form an index to allow certificates in a directory to be looked up by subject
171 =item B<-issuer_hash>
173 outputs the "hash" of the certificate issuer name.
177 outputs the OCSP hash values for the subject name and public key.
181 synonym for "-subject_hash" for backward compatibility reasons.
183 =item B<-subject_hash_old>
185 outputs the "hash" of the certificate subject name using the older algorithm
186 as used by OpenSSL versions before 1.0.0.
188 =item B<-issuer_hash_old>
190 outputs the "hash" of the certificate issuer name using the older algorithm
191 as used by OpenSSL versions before 1.0.0.
195 outputs the subject name.
199 outputs the issuer name.
201 =item B<-nameopt option>
203 option which determines how the subject or issuer names are displayed. The
204 B<option> argument can be a single option or multiple options separated by
205 commas. Alternatively the B<-nameopt> switch may be used more than once to
206 set multiple options. See the B<NAME OPTIONS> section for more information.
210 outputs the email address(es) if any.
214 outputs the OCSP responder address(es) if any.
218 prints out the start date of the certificate, that is the notBefore date.
222 prints out the expiry date of the certificate, that is the notAfter date.
226 prints out the start and expiry dates of a certificate.
228 =item B<-checkend arg>
230 checks if the certificate expires within the next B<arg> seconds and exits
231 non-zero if yes it will expire or zero if not.
233 =item B<-fingerprint>
235 prints out the digest of the DER encoded version of the whole certificate
236 (see digest options).
240 this outputs the certificate in the form of a C source file.
244 =head2 TRUST SETTINGS
246 Please note these options are currently experimental and may well change.
248 A B<trusted certificate> is an ordinary certificate which has several
249 additional pieces of information attached to it such as the permitted
250 and prohibited uses of the certificate and an "alias".
252 Normally when a certificate is being verified at least one certificate
253 must be "trusted". By default a trusted certificate must be stored
254 locally and must be a root CA: any certificate chain ending in this CA
255 is then usable for any purpose.
257 Trust settings currently are only used with a root CA. They allow a finer
258 control over the purposes the root CA can be used for. For example a CA
259 may be trusted for SSL client but not SSL server use.
261 See the description of the B<verify> utility for more information on the
262 meaning of trust settings.
264 Future versions of OpenSSL will recognize trust settings on any
265 certificate: not just root CAs.
272 this causes B<x509> to output a B<trusted> certificate. An ordinary
273 or trusted certificate can be input but by default an ordinary
274 certificate is output and any trust settings are discarded. With the
275 B<-trustout> option a trusted certificate is output. A trusted
276 certificate is automatically output if any trust settings are modified.
278 =item B<-setalias arg>
280 sets the alias of the certificate. This will allow the certificate
281 to be referred to using a nickname for example "Steve's Certificate".
285 outputs the certificate alias, if any.
289 clears all the permitted or trusted uses of the certificate.
293 clears all the prohibited or rejected uses of the certificate.
295 =item B<-addtrust arg>
297 adds a trusted certificate use.
298 Any object name can be used here but currently only B<clientAuth> (SSL client
299 use), B<serverAuth> (SSL server use), B<emailProtection> (S/MIME email) and
300 B<anyExtendedKeyUsage> are used.
301 As of OpenSSL 1.1.0, the last of these blocks all purposes when rejected or
302 enables all purposes when trusted.
303 Other OpenSSL applications may define additional uses.
305 =item B<-addreject arg>
307 adds a prohibited use. It accepts the same values as the B<-addtrust>
312 this option performs tests on the certificate extensions and outputs
313 the results. For a more complete description see the B<CERTIFICATE
318 =head2 SIGNING OPTIONS
320 The B<x509> utility can be used to sign certificates and requests: it
321 can thus behave like a "mini CA".
325 =item B<-signkey filename>
327 this option causes the input file to be self signed using the supplied
330 If the input file is a certificate it sets the issuer name to the
331 subject name (i.e. makes it self signed) changes the public key to the
332 supplied value and changes the start and end dates. The start date is
333 set to the current time and the end date is set to a value determined
334 by the B<-days> option. Any certificate extensions are retained unless
335 the B<-clrext> option is supplied; this includes, for example, any existing
336 key identifier extensions.
338 If the input is a certificate request then a self signed certificate
339 is created using the supplied private key using the subject name in
344 the key password source. For more information about the format of B<arg>
345 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)>.
349 delete any extensions from a certificate. This option is used when a
350 certificate is being created from another certificate (for example with
351 the B<-signkey> or the B<-CA> options). Normally all extensions are
354 =item B<-keyform PEM|DER>
356 specifies the format (DER or PEM) of the private key file used in the
361 specifies the number of days to make a certificate valid for. The default
366 converts a certificate into a certificate request. The B<-signkey> option
367 is used to pass the required private key.
371 by default a certificate is expected on input. With this option a
372 certificate request is expected instead.
374 =item B<-set_serial n>
376 specifies the serial number to use. This option can be used with either
377 the B<-signkey> or B<-CA> options. If used in conjunction with the B<-CA>
378 option the serial number file (as specified by the B<-CAserial> or
379 B<-CAcreateserial> options) is not used.
381 The serial number can be decimal or hex (if preceded by B<0x>).
383 =item B<-CA filename>
385 specifies the CA certificate to be used for signing. When this option is
386 present B<x509> behaves like a "mini CA". The input file is signed by this
387 CA using this option: that is its issuer name is set to the subject name
388 of the CA and it is digitally signed using the CAs private key.
390 This option is normally combined with the B<-req> option. Without the
391 B<-req> option the input is a certificate which must be self signed.
393 =item B<-CAkey filename>
395 sets the CA private key to sign a certificate with. If this option is
396 not specified then it is assumed that the CA private key is present in
397 the CA certificate file.
399 =item B<-CAserial filename>
401 sets the CA serial number file to use.
403 When the B<-CA> option is used to sign a certificate it uses a serial
404 number specified in a file. This file consist of one line containing
405 an even number of hex digits with the serial number to use. After each
406 use the serial number is incremented and written out to the file again.
408 The default filename consists of the CA certificate file base name with
409 ".srl" appended. For example if the CA certificate file is called
410 "mycacert.pem" it expects to find a serial number file called "mycacert.srl".
412 =item B<-CAcreateserial>
414 with this option the CA serial number file is created if it does not exist:
415 it will contain the serial number "02" and the certificate being signed will
416 have the 1 as its serial number. If the B<-CA> option is specified
417 and the serial number file does not exist a random number is generated;
418 this is the recommended practice.
420 =item B<-extfile filename>
422 file containing certificate extensions to use. If not specified then
423 no extensions are added to the certificate.
425 =item B<-extensions section>
427 the section to add certificate extensions from. If this option is not
428 specified then the extensions should either be contained in the unnamed
429 (default) section or the default section should contain a variable called
430 "extensions" which contains the section to use. See the
431 L<x509v3_config(5)> manual page for details of the
432 extension section format.
434 =item B<-force_pubkey key>
436 when a certificate is created set its public key to B<key> instead of the
437 key in the certificate or certificate request. This option is useful for
438 creating certificates where the algorithm can't normally sign requests, for
441 The format or B<key> can be specified using the B<-keyform> option.
447 The B<nameopt> command line switch determines how the subject and issuer
448 names are displayed. If no B<nameopt> switch is present the default "oneline"
449 format is used which is compatible with previous versions of OpenSSL.
450 Each option is described in detail below, all options can be preceded by
451 a B<-> to turn the option off. Only the first four will normally be used.
461 displays names compatible with RFC2253 equivalent to B<esc_2253>, B<esc_ctrl>,
462 B<esc_msb>, B<utf8>, B<dump_nostr>, B<dump_unknown>, B<dump_der>,
463 B<sep_comma_plus>, B<dn_rev> and B<sname>.
467 a oneline format which is more readable than RFC2253. It is equivalent to
468 specifying the B<esc_2253>, B<esc_ctrl>, B<esc_msb>, B<utf8>, B<dump_nostr>,
469 B<dump_der>, B<use_quote>, B<sep_comma_plus_space>, B<space_eq> and B<sname>
470 options. This is the I<default> of no name options are given explicitly.
474 a multiline format. It is equivalent B<esc_ctrl>, B<esc_msb>, B<sep_multiline>,
475 B<space_eq>, B<lname> and B<align>.
479 escape the "special" characters required by RFC2253 in a field That is
480 B<,+"E<lt>E<gt>;>. Additionally B<#> is escaped at the beginning of a string
481 and a space character at the beginning or end of a string.
485 escape control characters. That is those with ASCII values less than
486 0x20 (space) and the delete (0x7f) character. They are escaped using the
487 RFC2253 \XX notation (where XX are two hex digits representing the
492 escape characters with the MSB set, that is with ASCII values larger than
497 escapes some characters by surrounding the whole string with B<"> characters,
498 without the option all escaping is done with the B<\> character.
502 convert all strings to UTF8 format first. This is required by RFC2253. If
503 you are lucky enough to have a UTF8 compatible terminal then the use
504 of this option (and B<not> setting B<esc_msb>) may result in the correct
505 display of multibyte (international) characters. Is this option is not
506 present then multibyte characters larger than 0xff will be represented
507 using the format \UXXXX for 16 bits and \WXXXXXXXX for 32 bits.
508 Also if this option is off any UTF8Strings will be converted to their
509 character form first.
513 this option does not attempt to interpret multibyte characters in any
514 way. That is their content octets are merely dumped as though one octet
515 represents each character. This is useful for diagnostic purposes but
516 will result in rather odd looking output.
520 show the type of the ASN1 character string. The type precedes the
521 field contents. For example "BMPSTRING: Hello World".
525 when this option is set any fields that need to be hexdumped will
526 be dumped using the DER encoding of the field. Otherwise just the
527 content octets will be displayed. Both options use the RFC2253
532 dump non character string types (for example OCTET STRING) if this
533 option is not set then non character string types will be displayed
534 as though each content octet represents a single character.
538 dump all fields. This option when used with B<dump_der> allows the
539 DER encoding of the structure to be unambiguously determined.
541 =item B<dump_unknown>
543 dump any field whose OID is not recognised by OpenSSL.
545 =item B<sep_comma_plus>, B<sep_comma_plus_space>, B<sep_semi_plus_space>,
548 these options determine the field separators. The first character is
549 between RDNs and the second between multiple AVAs (multiple AVAs are
550 very rare and their use is discouraged). The options ending in
551 "space" additionally place a space after the separator to make it
552 more readable. The B<sep_multiline> uses a linefeed character for
553 the RDN separator and a spaced B<+> for the AVA separator. It also
554 indents the fields by four characters. If no field separator is specified
555 then B<sep_comma_plus_space> is used by default.
559 reverse the fields of the DN. This is required by RFC2253. As a side
560 effect this also reverses the order of multiple AVAs but this is
563 =item B<nofname>, B<sname>, B<lname>, B<oid>
565 these options alter how the field name is displayed. B<nofname> does
566 not display the field at all. B<sname> uses the "short name" form
567 (CN for commonName for example). B<lname> uses the long form.
568 B<oid> represents the OID in numerical form and is useful for
573 align field values for a more readable output. Only usable with
578 places spaces round the B<=> character which follows the field
585 As well as customising the name output format, it is also possible to
586 customise the actual fields printed using the B<certopt> options when
587 the B<text> option is present. The default behaviour is to print all fields.
593 use the old format. This is equivalent to specifying no output options at all.
597 don't print header information: that is the lines saying "Certificate" and "Data".
601 don't print out the version number.
605 don't print out the serial number.
609 don't print out the signature algorithm used.
613 don't print the validity, that is the B<notBefore> and B<notAfter> fields.
617 don't print out the subject name.
621 don't print out the issuer name.
625 don't print out the public key.
629 don't give a hexadecimal dump of the certificate signature.
633 don't print out certificate trust information.
635 =item B<no_extensions>
637 don't print out any X509V3 extensions.
641 retain default extension behaviour: attempt to print out unsupported certificate extensions.
645 print an error message for unsupported certificate extensions.
649 ASN1 parse unsupported extensions.
653 hex dump unsupported extensions.
657 the value used by the B<ca> utility, equivalent to B<no_issuer>, B<no_pubkey>, B<no_header>,
658 B<no_version>, B<no_sigdump> and B<no_signame>.
664 Note: in these examples the '\' means the example should be all on one
667 Display the contents of a certificate:
669 openssl x509 -in cert.pem -noout -text
671 Display the certificate serial number:
673 openssl x509 -in cert.pem -noout -serial
675 Display the certificate subject name:
677 openssl x509 -in cert.pem -noout -subject
679 Display the certificate subject name in RFC2253 form:
681 openssl x509 -in cert.pem -noout -subject -nameopt RFC2253
683 Display the certificate subject name in oneline form on a terminal
686 openssl x509 -in cert.pem -noout -subject -nameopt oneline,-esc_msb
688 Display the certificate MD5 fingerprint:
690 openssl x509 -in cert.pem -noout -fingerprint
692 Display the certificate SHA1 fingerprint:
694 openssl x509 -sha1 -in cert.pem -noout -fingerprint
696 Convert a certificate from PEM to DER format:
698 openssl x509 -in cert.pem -inform PEM -out cert.der -outform DER
700 Convert a certificate to a certificate request:
702 openssl x509 -x509toreq -in cert.pem -out req.pem -signkey key.pem
704 Convert a certificate request into a self signed certificate using
707 openssl x509 -req -in careq.pem -extfile openssl.cnf -extensions v3_ca \
708 -signkey key.pem -out cacert.pem
710 Sign a certificate request using the CA certificate above and add user
711 certificate extensions:
713 openssl x509 -req -in req.pem -extfile openssl.cnf -extensions v3_usr \
714 -CA cacert.pem -CAkey key.pem -CAcreateserial
717 Set a certificate to be trusted for SSL client use and change set its alias to
720 openssl x509 -in cert.pem -addtrust clientAuth \
721 -setalias "Steve's Class 1 CA" -out trust.pem
725 The PEM format uses the header and footer lines:
727 -----BEGIN CERTIFICATE-----
728 -----END CERTIFICATE-----
730 it will also handle files containing:
732 -----BEGIN X509 CERTIFICATE-----
733 -----END X509 CERTIFICATE-----
735 Trusted certificates have the lines
737 -----BEGIN TRUSTED CERTIFICATE-----
738 -----END TRUSTED CERTIFICATE-----
740 The conversion to UTF8 format used with the name options assumes that
741 T61Strings use the ISO8859-1 character set. This is wrong but Netscape
742 and MSIE do this as do many certificates. So although this is incorrect
743 it is more likely to display the majority of certificates correctly.
745 The B<-fingerprint> option takes the digest of the DER encoded certificate.
746 This is commonly called a "fingerprint". Because of the nature of message
747 digests the fingerprint of a certificate is unique to that certificate and
748 two certificates with the same fingerprint can be considered to be the same.
750 The Netscape fingerprint uses MD5 whereas MSIE uses SHA1.
752 The B<-email> option searches the subject name and the subject alternative
753 name extension. Only unique email addresses will be printed out: it will
754 not print the same address more than once.
756 =head1 CERTIFICATE EXTENSIONS
758 The B<-purpose> option checks the certificate extensions and determines
759 what the certificate can be used for. The actual checks done are rather
760 complex and include various hacks and workarounds to handle broken
761 certificates and software.
763 The same code is used when verifying untrusted certificates in chains
764 so this section is useful if a chain is rejected by the verify code.
766 The basicConstraints extension CA flag is used to determine whether the
767 certificate can be used as a CA. If the CA flag is true then it is a CA,
768 if the CA flag is false then it is not a CA. B<All> CAs should have the
771 If the basicConstraints extension is absent then the certificate is
772 considered to be a "possible CA" other extensions are checked according
773 to the intended use of the certificate. A warning is given in this case
774 because the certificate should really not be regarded as a CA: however
775 it is allowed to be a CA to work around some broken software.
777 If the certificate is a V1 certificate (and thus has no extensions) and
778 it is self signed it is also assumed to be a CA but a warning is again
779 given: this is to work around the problem of Verisign roots which are V1
780 self signed certificates.
782 If the keyUsage extension is present then additional restraints are
783 made on the uses of the certificate. A CA certificate B<must> have the
784 keyCertSign bit set if the keyUsage extension is present.
786 The extended key usage extension places additional restrictions on the
787 certificate uses. If this extension is present (whether critical or not)
788 the key can only be used for the purposes specified.
790 A complete description of each test is given below. The comments about
791 basicConstraints and keyUsage and V1 certificates above apply to B<all>
799 The extended key usage extension must be absent or include the "web client
800 authentication" OID. keyUsage must be absent or it must have the
801 digitalSignature bit set. Netscape certificate type must be absent or it must
802 have the SSL client bit set.
804 =item B<SSL Client CA>
806 The extended key usage extension must be absent or include the "web client
807 authentication" OID. Netscape certificate type must be absent or it must have
808 the SSL CA bit set: this is used as a work around if the basicConstraints
813 The extended key usage extension must be absent or include the "web server
814 authentication" and/or one of the SGC OIDs. keyUsage must be absent or it
815 must have the digitalSignature, the keyEncipherment set or both bits set.
816 Netscape certificate type must be absent or have the SSL server bit set.
818 =item B<SSL Server CA>
820 The extended key usage extension must be absent or include the "web server
821 authentication" and/or one of the SGC OIDs. Netscape certificate type must
822 be absent or the SSL CA bit must be set: this is used as a work around if the
823 basicConstraints extension is absent.
825 =item B<Netscape SSL Server>
827 For Netscape SSL clients to connect to an SSL server it must have the
828 keyEncipherment bit set if the keyUsage extension is present. This isn't
829 always valid because some cipher suites use the key for digital signing.
830 Otherwise it is the same as a normal SSL server.
832 =item B<Common S/MIME Client Tests>
834 The extended key usage extension must be absent or include the "email
835 protection" OID. Netscape certificate type must be absent or should have the
836 S/MIME bit set. If the S/MIME bit is not set in netscape certificate type
837 then the SSL client bit is tolerated as an alternative but a warning is shown:
838 this is because some Verisign certificates don't set the S/MIME bit.
840 =item B<S/MIME Signing>
842 In addition to the common S/MIME client tests the digitalSignature bit must
843 be set if the keyUsage extension is present.
845 =item B<S/MIME Encryption>
847 In addition to the common S/MIME tests the keyEncipherment bit must be set
848 if the keyUsage extension is present.
852 The extended key usage extension must be absent or include the "email
853 protection" OID. Netscape certificate type must be absent or must have the
854 S/MIME CA bit set: this is used as a work around if the basicConstraints
859 The keyUsage extension must be absent or it must have the CRL signing bit
862 =item B<CRL Signing CA>
864 The normal CA tests apply. Except in this case the basicConstraints extension
871 Extensions in certificates are not transferred to certificate requests and
874 It is possible to produce invalid certificates or requests by specifying the
875 wrong private key or using inconsistent options in some cases: these should
878 There should be options to explicitly set such things as start and end
879 dates rather than an offset from the current time.
883 L<req(1)>, L<ca(1)>, L<genrsa(1)>,
884 L<gendsa(1)>, L<verify(1)>,
889 The hash algorithm used in the B<-subject_hash> and B<-issuer_hash> options
890 before OpenSSL 1.0.0 was based on the deprecated MD5 algorithm and the encoding
891 of the distinguished name. In OpenSSL 1.0.0 and later it is based on a
892 canonical version of the DN using SHA1. This means that any directories using
893 the old form must have their links rebuilt using B<c_rehash> or similar.