6 x509 - Certificate display and signing utility
11 [B<-inform DER|PEM|NET>]
12 [B<-outform DER|PEM|NET>]
15 [B<-CAkeyform DER|PEM>]
40 [B<-signkey filename>]
46 [B<-CAserial filename>]
49 [B<-md2|-md5|-sha1|-mdc2>]
51 [B<-extfile filename>]
52 [B<-extensions section>]
56 The B<x509> command is a multi purpose certificate utility. It can be
57 used to display certificate information, convert certificates to
58 various forms, sign certificate requests like a "mini CA" or edit
59 certificate trust settings.
61 Since there are a large number of options they will split up into
65 =head1 INPUT, OUTPUT AND GENERAL PURPOSE OPTIONS
69 =item B<-inform DER|PEM|NET>
71 This specifies the input format normally the command will expect an X509
72 certificate but this can change if other options such as B<-req> are
73 present. The DER format is the DER encoding of the certificate and PEM
74 is the base64 encoding of the DER encoding with header and footer lines
75 added. The NET option is an obscure Netscape server format that is now
78 =item B<-outform DER|PEM|NET>
80 This specifies the output format, the options have the same meaning as the
85 This specifies the input filename to read a certificate from or standard input
86 if this option is not specified.
88 =item B<-out filename>
90 This specifies the output filename to write to or standard output by
93 =item B<-md2|-md5|-sha1|-mdc2>
95 the digest to use. This affects any signing or display option that uses a message
96 digest, such as the B<-fingerprint>, B<-signkey> and B<-CA> options. If not
97 specified then MD5 is used. If the key being used to sign with is a DSA key then
98 this option has no effect: SHA1 is always used with DSA keys.
103 =head1 DISPLAY OPTIONS
105 Note: the B<-alias> and B<-purpose> options are also display options
106 but are described in the B<TRUST OPTIONS> section.
112 prints out the certificate in text form. Full details are output including the
113 public key, signature algorithms, issuer and subject names, serial number
114 any extensions present and any trust settings.
116 =item B<-certopt option>
118 customise the output format used with B<-text>. The B<option> argument can be
119 a single option or multiple options separated by commas. The B<-certopt> switch
120 may be also be used more than once to set multiple options. See the B<TEXT OPTIONS>
121 section for more information.
125 this option prevents output of the encoded version of the request.
129 this option prints out the value of the modulus of the public key
130 contained in the certificate.
134 outputs the certificate serial number.
138 outputs the "hash" of the certificate subject name. This is used in OpenSSL to
139 form an index to allow certificates in a directory to be looked up by subject
144 outputs the subject name.
148 outputs the issuer name.
150 =item B<-nameopt option>
152 option which determines how the subject or issuer names are displayed. The
153 B<option> argument can be a single option or multiple options separated by
154 commas. Alternatively the B<-nameopt> switch may be used more than once to
155 set multiple options. See the B<NAME OPTIONS> section for more information.
159 outputs the email address(es) if any.
163 prints out the start date of the certificate, that is the notBefore date.
167 prints out the expiry date of the certificate, that is the notAfter date.
171 prints out the start and expiry dates of a certificate.
173 =item B<-fingerprint>
175 prints out the digest of the DER encoded version of the whole certificate
176 (see digest options).
180 this outputs the certificate in the form of a C source file.
184 =head1 TRUST SETTINGS
186 Please note these options are currently experimental and may well change.
188 A B<trusted certificate> is an ordinary certificate which has several
189 additional pieces of information attached to it such as the permitted
190 and prohibited uses of the certificate and an "alias".
192 Normally when a certificate is being verified at least one certificate
193 must be "trusted". By default a trusted certificate must be stored
194 locally and must be a root CA: any certificate chain ending in this CA
195 is then usable for any purpose.
197 Trust settings currently are only used with a root CA. They allow a finer
198 control over the purposes the root CA can be used for. For example a CA
199 may be trusted for SSL client but not SSL server use.
201 See the description of the B<verify> utility for more information on the
202 meaning of trust settings.
204 Future versions of OpenSSL will recognize trust settings on any
205 certificate: not just root CAs.
212 this causes B<x509> to output a B<trusted> certificate. An ordinary
213 or trusted certificate can be input but by default an ordinary
214 certificate is output and any trust settings are discarded. With the
215 B<-trustout> option a trusted certificate is output. A trusted
216 certificate is automatically output if any trust settings are modified.
218 =item B<-setalias arg>
220 sets the alias of the certificate. This will allow the certificate
221 to be referred to using a nickname for example "Steve's Certificate".
225 outputs the certificate alias, if any.
229 clears all the permitted or trusted uses of the certificate.
233 clears all the prohibited or rejected uses of the certificate.
235 =item B<-addtrust arg>
237 adds a trusted certificate use. Any object name can be used here
238 but currently only B<clientAuth> (SSL client use), B<serverAuth>
239 (SSL server use) and B<emailProtection> (S/MIME email) are used.
240 Other OpenSSL applications may define additional uses.
242 =item B<-addreject arg>
244 adds a prohibited use. It accepts the same values as the B<-addtrust>
249 this option performs tests on the certificate extensions and outputs
250 the results. For a more complete description see the B<CERTIFICATE
255 =head1 SIGNING OPTIONS
257 The B<x509> utility can be used to sign certificates and requests: it
258 can thus behave like a "mini CA".
262 =item B<-signkey filename>
264 this option causes the input file to be self signed using the supplied
267 If the input file is a certificate it sets the issuer name to the
268 subject name (i.e. makes it self signed) changes the public key to the
269 supplied value and changes the start and end dates. The start date is
270 set to the current time and the end date is set to a value determined
271 by the B<-days> option. Any certificate extensions are retained unless
272 the B<-clrext> option is supplied.
274 If the input is a certificate request then a self signed certificate
275 is created using the supplied private key using the subject name in
280 delete any extensions from a certificate. This option is used when a
281 certificate is being created from another certificate (for example with
282 the B<-signkey> or the B<-CA> options). Normally all extensions are
285 =item B<-keyform PEM|DER>
287 specifies the format (DER or PEM) of the private key file used in the
292 specifies the number of days to make a certificate valid for. The default
297 converts a certificate into a certificate request. The B<-signkey> option
298 is used to pass the required private key.
302 by default a certificate is expected on input. With this option a
303 certificate request is expected instead.
305 =item B<-set_serial n>
307 specifies the serial number to use. This option can be used with either
308 the B<-signkey> or B<-CA> options. If used in conjunction with the B<-CA>
309 option the serial number file (as specified by the B<-CAserial> or
310 B<-CAcreateserial> options) is not used.
312 The serial number can be decimal or hex (if preceded by B<0x>). Negative
313 serial numbers can also be specified but their use is not recommended.
315 =item B<-CA filename>
317 specifies the CA certificate to be used for signing. When this option is
318 present B<x509> behaves like a "mini CA". The input file is signed by this
319 CA using this option: that is its issuer name is set to the subject name
320 of the CA and it is digitally signed using the CAs private key.
322 This option is normally combined with the B<-req> option. Without the
323 B<-req> option the input is a certificate which must be self signed.
325 =item B<-CAkey filename>
327 sets the CA private key to sign a certificate with. If this option is
328 not specified then it is assumed that the CA private key is present in
329 the CA certificate file.
331 =item B<-CAserial filename>
333 sets the CA serial number file to use.
335 When the B<-CA> option is used to sign a certificate it uses a serial
336 number specified in a file. This file consist of one line containing
337 an even number of hex digits with the serial number to use. After each
338 use the serial number is incremented and written out to the file again.
340 The default filename consists of the CA certificate file base name with
341 ".srl" appended. For example if the CA certificate file is called
342 "mycacert.pem" it expects to find a serial number file called "mycacert.srl".
344 =item B<-CAcreateserial filename>
346 with this option the CA serial number file is created if it does not exist:
347 it will contain the serial number "02" and the certificate being signed will
348 have the 1 as its serial number. Normally if the B<-CA> option is specified
349 and the serial number file does not exist it is an error.
351 =item B<-extfile filename>
353 file containing certificate extensions to use. If not specified then
354 no extensions are added to the certificate.
356 =item B<-extensions section>
358 the section to add certificate extensions from. If this option is not
359 specified then the extensions should either be contained in the unnamed
360 (default) section or the default section should contain a variable called
361 "extensions" which contains the section to use.
367 The B<nameopt> command line switch determines how the subject and issuer
368 names are displayed. If no B<nameopt> switch is present the default "oneline"
369 format is used which is compatible with previous versions of OpenSSL.
370 Each option is described in detail below, all options can be preceded by
371 a B<-> to turn the option off. Only the first four will normally be used.
377 use the old format. This is equivalent to specifying no name options at all.
381 displays names compatible with RFC2253 equivalent to B<esc_2253>, B<esc_ctrl>,
382 B<esc_msb>, B<utf8>, B<dump_nostr>, B<dump_unknown>, B<dump_der>,
383 B<sep_comma_plus>, B<dn_rev> and B<sname>.
387 a oneline format which is more readable than RFC2253. It is equivalent to
388 specifying the B<esc_2253>, B<esc_ctrl>, B<esc_msb>, B<utf8>, B<dump_nostr>,
389 B<dump_der>, B<use_quote>, B<sep_comma_plus_spc>, B<spc_eq> and B<sname>
394 a multiline format. It is equivalent B<esc_ctrl>, B<esc_msb>, B<sep_multiline>,
395 B<spc_eq>, B<lname> and B<align>.
399 escape the "special" characters required by RFC2253 in a field That is
400 B<,+"E<lt>E<gt>;>. Additionally B<#> is escaped at the beginning of a string
401 and a space character at the beginning or end of a string.
405 escape control characters. That is those with ASCII values less than
406 0x20 (space) and the delete (0x7f) character. They are escaped using the
407 RFC2253 \XX notation (where XX are two hex digits representing the
412 escape characters with the MSB set, that is with ASCII values larger than
417 escapes some characters by surrounding the whole string with B<"> characters,
418 without the option all escaping is done with the B<\> character.
422 convert all strings to UTF8 format first. This is required by RFC2253. If
423 you are lucky enough to have a UTF8 compatible terminal then the use
424 of this option (and B<not> setting B<esc_msb>) may result in the correct
425 display of multibyte (international) characters. Is this option is not
426 present then multibyte characters larger than 0xff will be represented
427 using the format \UXXXX for 16 bits and \WXXXXXXXX for 32 bits.
428 Also if this option is off any UTF8Strings will be converted to their
429 character form first.
433 this option does not attempt to interpret multibyte characters in any
434 way. That is their content octets are merely dumped as though one octet
435 represents each character. This is useful for diagnostic purposes but
436 will result in rather odd looking output.
440 show the type of the ASN1 character string. The type precedes the
441 field contents. For example "BMPSTRING: Hello World".
445 when this option is set any fields that need to be hexdumped will
446 be dumped using the DER encoding of the field. Otherwise just the
447 content octets will be displayed. Both options use the RFC2253
452 dump non character string types (for example OCTET STRING) if this
453 option is not set then non character string types will be displayed
454 as though each content octet represents a single character.
458 dump all fields. This option when used with B<dump_der> allows the
459 DER encoding of the structure to be unambiguously determined.
461 =item B<dump_unknown>
463 dump any field whose OID is not recognised by OpenSSL.
465 =item B<sep_comma_plus>, B<sep_comma_plus_space>, B<sep_semi_plus_space>,
468 these options determine the field separators. The first character is
469 between RDNs and the second between multiple AVAs (multiple AVAs are
470 very rare and their use is discouraged). The options ending in
471 "space" additionally place a space after the separator to make it
472 more readable. The B<sep_multiline> uses a linefeed character for
473 the RDN separator and a spaced B<+> for the AVA separator. It also
474 indents the fields by four characters.
478 reverse the fields of the DN. This is required by RFC2253. As a side
479 effect this also reverses the order of multiple AVAs but this is
482 =item B<nofname>, B<sname>, B<lname>, B<oid>
484 these options alter how the field name is displayed. B<nofname> does
485 not display the field at all. B<sname> uses the "short name" form
486 (CN for commonName for example). B<lname> uses the long form.
487 B<oid> represents the OID in numerical form and is useful for
492 align field values for a more readable output. Only usable with
497 places spaces round the B<=> character which follows the field
504 As well as customising the name output format, it is also possible to
505 customise the actual fields printed using the B<certopt> options when
506 the B<text> option is present. The default behaviour is to print all fields.
510 use the old format. This is equivalent to specifying no output options at all.
514 don't print header information: that is the lines saying "Certificate" and "Data".
518 don't print out the version number.
522 don't print out the serial number.
526 don't print out the signature algorithm used.
530 don't print the validity, that is the B<notBefore> and B<notAfter> fields.
534 don't print out the subject name.
538 don't print out the issuer name.
542 don't print out the public key.
546 don't give a hexadecimal dump of the certificate signature.
550 don't print out certificate trust information.
552 =item B<no_extensions>
554 don't print out any X509V3 extensions.
558 retain default extension behaviour: attempt to print out unsupported certificate extensions.
562 print an error message for unsupported certificate extensions.
566 ASN1 parse unsupported extensions.
570 hex dump unsupported extensions.
574 the value used by the B<ca> utility, equivalent to B<no_issuer>, B<no_pubkey>, B<no_header>,
575 B<no_version>, B<no_sigdump> and B<no_signame>.
585 Note: in these examples the '\' means the example should be all on one
588 Display the contents of a certificate:
590 openssl x509 -in cert.pem -noout -text
592 Display the certificate serial number:
594 openssl x509 -in cert.pem -noout -serial
596 Display the certificate subject name:
598 openssl x509 -in cert.pem -noout -subject
600 Display the certificate subject name in RFC2253 form:
602 openssl x509 -in cert.pem -noout -subject -nameopt RFC2253
604 Display the certificate subject name in oneline form on a terminal
607 openssl x509 -in cert.pem -noout -subject -nameopt oneline,-escmsb
609 Display the certificate MD5 fingerprint:
611 openssl x509 -in cert.pem -noout -fingerprint
613 Display the certificate SHA1 fingerprint:
615 openssl x509 -sha1 -in cert.pem -noout -fingerprint
617 Convert a certificate from PEM to DER format:
619 openssl x509 -in cert.pem -inform PEM -out cert.der -outform DER
621 Convert a certificate to a certificate request:
623 openssl x509 -x509toreq -in cert.pem -out req.pem -signkey key.pem
625 Convert a certificate request into a self signed certificate using
628 openssl x509 -req -in careq.pem -extfile openssl.cnf -extensions v3_ca \
629 -signkey key.pem -out cacert.pem
631 Sign a certificate request using the CA certificate above and add user
632 certificate extensions:
634 openssl x509 -req -in req.pem -extfile openssl.cnf -extensions v3_usr \
635 -CA cacert.pem -CAkey key.pem -CAcreateserial
638 Set a certificate to be trusted for SSL client use and change set its alias to
641 openssl x509 -in cert.pem -addtrust sslclient \
642 -alias "Steve's Class 1 CA" -out trust.pem
646 The PEM format uses the header and footer lines:
648 -----BEGIN CERTIFICATE----
649 -----END CERTIFICATE----
651 it will also handle files containing:
653 -----BEGIN X509 CERTIFICATE----
654 -----END X509 CERTIFICATE----
656 Trusted certificates have the lines
658 -----BEGIN TRUSTED CERTIFICATE----
659 -----END TRUSTED CERTIFICATE----
661 The conversion to UTF8 format used with the name options assumes that
662 T61Strings use the ISO8859-1 character set. This is wrong but Netscape
663 and MSIE do this as do many certificates. So although this is incorrect
664 it is more likely to display the majority of certificates correctly.
666 The B<-fingerprint> option takes the digest of the DER encoded certificate.
667 This is commonly called a "fingerprint". Because of the nature of message
668 digests the fingerprint of a certificate is unique to that certificate and
669 two certificates with the same fingerprint can be considered to be the same.
671 The Netscape fingerprint uses MD5 whereas MSIE uses SHA1.
673 The B<-email> option searches the subject name and the subject alternative
674 name extension. Only unique email addresses will be printed out: it will
675 not print the same address more than once.
677 =head1 CERTIFICATE EXTENSIONS
679 The B<-purpose> option checks the certificate extensions and determines
680 what the certificate can be used for. The actual checks done are rather
681 complex and include various hacks and workarounds to handle broken
682 certificates and software.
684 The same code is used when verifying untrusted certificates in chains
685 so this section is useful if a chain is rejected by the verify code.
687 The basicConstraints extension CA flag is used to determine whether the
688 certificate can be used as a CA. If the CA flag is true then it is a CA,
689 if the CA flag is false then it is not a CA. B<All> CAs should have the
692 If the basicConstraints extension is absent then the certificate is
693 considered to be a "possible CA" other extensions are checked according
694 to the intended use of the certificate. A warning is given in this case
695 because the certificate should really not be regarded as a CA: however
696 it is allowed to be a CA to work around some broken software.
698 If the certificate is a V1 certificate (and thus has no extensions) and
699 it is self signed it is also assumed to be a CA but a warning is again
700 given: this is to work around the problem of Verisign roots which are V1
701 self signed certificates.
703 If the keyUsage extension is present then additional restraints are
704 made on the uses of the certificate. A CA certificate B<must> have the
705 keyCertSign bit set if the keyUsage extension is present.
707 The extended key usage extension places additional restrictions on the
708 certificate uses. If this extension is present (whether critical or not)
709 the key can only be used for the purposes specified.
711 A complete description of each test is given below. The comments about
712 basicConstraints and keyUsage and V1 certificates above apply to B<all>
720 The extended key usage extension must be absent or include the "web client
721 authentication" OID. keyUsage must be absent or it must have the
722 digitalSignature bit set. Netscape certificate type must be absent or it must
723 have the SSL client bit set.
725 =item B<SSL Client CA>
727 The extended key usage extension must be absent or include the "web client
728 authentication" OID. Netscape certificate type must be absent or it must have
729 the SSL CA bit set: this is used as a work around if the basicConstraints
734 The extended key usage extension must be absent or include the "web server
735 authentication" and/or one of the SGC OIDs. keyUsage must be absent or it
736 must have the digitalSignature, the keyEncipherment set or both bits set.
737 Netscape certificate type must be absent or have the SSL server bit set.
739 =item B<SSL Server CA>
741 The extended key usage extension must be absent or include the "web server
742 authentication" and/or one of the SGC OIDs. Netscape certificate type must
743 be absent or the SSL CA bit must be set: this is used as a work around if the
744 basicConstraints extension is absent.
746 =item B<Netscape SSL Server>
748 For Netscape SSL clients to connect to an SSL server it must have the
749 keyEncipherment bit set if the keyUsage extension is present. This isn't
750 always valid because some cipher suites use the key for digital signing.
751 Otherwise it is the same as a normal SSL server.
753 =item B<Common S/MIME Client Tests>
755 The extended key usage extension must be absent or include the "email
756 protection" OID. Netscape certificate type must be absent or should have the
757 S/MIME bit set. If the S/MIME bit is not set in netscape certificate type
758 then the SSL client bit is tolerated as an alternative but a warning is shown:
759 this is because some Verisign certificates don't set the S/MIME bit.
761 =item B<S/MIME Signing>
763 In addition to the common S/MIME client tests the digitalSignature bit must
764 be set if the keyUsage extension is present.
766 =item B<S/MIME Encryption>
768 In addition to the common S/MIME tests the keyEncipherment bit must be set
769 if the keyUsage extension is present.
773 The extended key usage extension must be absent or include the "email
774 protection" OID. Netscape certificate type must be absent or must have the
775 S/MIME CA bit set: this is used as a work around if the basicConstraints
780 The keyUsage extension must be absent or it must have the CRL signing bit
783 =item B<CRL Signing CA>
785 The normal CA tests apply. Except in this case the basicConstraints extension
792 Extensions in certificates are not transferred to certificate requests and
795 It is possible to produce invalid certificates or requests by specifying the
796 wrong private key or using inconsistent options in some cases: these should
799 There should be options to explicitly set such things as start and end
800 dates rather than an offset from the current time.
802 The code to implement the verify behaviour described in the B<TRUST SETTINGS>
803 is currently being developed. It thus describes the intended behaviour rather
804 than the current behaviour. It is hoped that it will represent reality in
805 OpenSSL 0.9.5 and later.
809 L<req(1)|req(1)>, L<ca(1)|ca(1)>, L<genrsa(1)|genrsa(1)>,
810 L<gendsa(1)|gendsa(1)>, L<verify(1)|verify(1)>