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>. This option may be used more
119 than once to set multiple options. See the B<OUTPUT OPTIONS> section for
124 this option prevents output of the encoded version of the request.
128 this option prints out the value of the modulus of the public key
129 contained in the certificate.
133 outputs the certificate serial number.
137 outputs the "hash" of the certificate subject name. This is used in OpenSSL to
138 form an index to allow certificates in a directory to be looked up by subject
143 outputs the subject name.
147 outputs the issuer name.
149 =item B<-nameopt option>
151 option which determines how the subject or issuer names are displayed. This
152 option may be used more than once to set multiple options. See the B<NAME
153 OPTIONS> section for more information.
157 outputs the email address(es) if any.
161 prints out the start date of the certificate, that is the notBefore date.
165 prints out the expiry date of the certificate, that is the notAfter date.
169 prints out the start and expiry dates of a certificate.
171 =item B<-fingerprint>
173 prints out the digest of the DER encoded version of the whole certificate
174 (see digest options).
178 this outputs the certificate in the form of a C source file.
182 =head1 TRUST SETTINGS
184 Please note these options are currently experimental and may well change.
186 A B<trusted certificate> is an ordinary certificate which has several
187 additional pieces of information attached to it such as the permitted
188 and prohibited uses of the certificate and an "alias".
190 Normally when a certificate is being verified at least one certificate
191 must be "trusted". By default a trusted certificate must be stored
192 locally and must be a root CA: any certificate chain ending in this CA
193 is then usable for any purpose.
195 Trust settings currently are only used with a root CA. They allow a finer
196 control over the purposes the root CA can be used for. For example a CA
197 may be trusted for SSL client but not SSL server use.
199 See the description of the B<verify> utility for more information on the
200 meaning of trust settings.
202 Future versions of OpenSSL will recognize trust settings on any
203 certificate: not just root CAs.
210 this causes B<x509> to output a B<trusted> certificate. An ordinary
211 or trusted certificate can be input but by default an ordinary
212 certificate is output and any trust settings are discarded. With the
213 B<-trustout> option a trusted certificate is output. A trusted
214 certificate is automatically output if any trust settings are modified.
216 =item B<-setalias arg>
218 sets the alias of the certificate. This will allow the certificate
219 to be referred to using a nickname for example "Steve's Certificate".
223 outputs the certificate alias, if any.
227 clears all the permitted or trusted uses of the certificate.
231 clears all the prohibited or rejected uses of the certificate.
233 =item B<-addtrust arg>
235 adds a trusted certificate use. Any object name can be used here
236 but currently only B<clientAuth> (SSL client use), B<serverAuth>
237 (SSL server use) and B<emailProtection> (S/MIME email) are used.
238 Other OpenSSL applications may define additional uses.
240 =item B<-addreject arg>
242 adds a prohibited use. It accepts the same values as the B<-addtrust>
247 this option performs tests on the certificate extensions and outputs
248 the results. For a more complete description see the B<CERTIFICATE
253 =head1 SIGNING OPTIONS
255 The B<x509> utility can be used to sign certificates and requests: it
256 can thus behave like a "mini CA".
260 =item B<-signkey filename>
262 this option causes the input file to be self signed using the supplied
265 If the input file is a certificate it sets the issuer name to the
266 subject name (i.e. makes it self signed) changes the public key to the
267 supplied value and changes the start and end dates. The start date is
268 set to the current time and the end date is set to a value determined
269 by the B<-days> option. Any certificate extensions are retained unless
270 the B<-clrext> option is supplied.
272 If the input is a certificate request then a self signed certificate
273 is created using the supplied private key using the subject name in
278 delete any extensions from a certificate. This option is used when a
279 certificate is being created from another certificate (for example with
280 the B<-signkey> or the B<-CA> options). Normally all extensions are
283 =item B<-keyform PEM|DER>
285 specifies the format (DER or PEM) of the private key file used in the
290 specifies the number of days to make a certificate valid for. The default
295 converts a certificate into a certificate request. The B<-signkey> option
296 is used to pass the required private key.
300 by default a certificate is expected on input. With this option a
301 certificate request is expected instead.
303 =item B<-set_serial n>
305 specifies the serial number to use. This option can be used with either
306 the B<-signkey> or B<-CA> options. If used in conjunction with the B<-CA>
307 option the serial number file (as specified by the B<-CAserial> or
308 B<-CAcreateserial> options) is not used.
310 The serial number can be decimal or hex (if preceded by B<0x>). Negative
311 serial numbers can also be specified but their use is not recommended.
313 =item B<-CA filename>
315 specifies the CA certificate to be used for signing. When this option is
316 present B<x509> behaves like a "mini CA". The input file is signed by this
317 CA using this option: that is its issuer name is set to the subject name
318 of the CA and it is digitally signed using the CAs private key.
320 This option is normally combined with the B<-req> option. Without the
321 B<-req> option the input is a certificate which must be self signed.
323 =item B<-CAkey filename>
325 sets the CA private key to sign a certificate with. If this option is
326 not specified then it is assumed that the CA private key is present in
327 the CA certificate file.
329 =item B<-CAserial filename>
331 sets the CA serial number file to use.
333 When the B<-CA> option is used to sign a certificate it uses a serial
334 number specified in a file. This file consist of one line containing
335 an even number of hex digits with the serial number to use. After each
336 use the serial number is incremented and written out to the file again.
338 The default filename consists of the CA certificate file base name with
339 ".srl" appended. For example if the CA certificate file is called
340 "mycacert.pem" it expects to find a serial number file called "mycacert.srl".
342 =item B<-CAcreateserial filename>
344 with this option the CA serial number file is created if it does not exist:
345 it will contain the serial number "02" and the certificate being signed will
346 have the 1 as its serial number. Normally if the B<-CA> option is specified
347 and the serial number file does not exist it is an error.
349 =item B<-extfile filename>
351 file containing certificate extensions to use. If not specified then
352 no extensions are added to the certificate.
354 =item B<-extensions section>
356 the section to add certificate extensions from. If this option is not
357 specified then the extensions should either be contained in the unnamed
358 (default) section or the default section should contain a variable called
359 "extensions" which contains the section to use.
365 The B<nameopt> command line switch determines how the subject and issuer
366 names are displayed. If no B<nameopt> switch is present the default "oneline"
367 format is used which is compatible with previous versions of OpenSSL.
368 Each option is described in detail below, all options can be preceded by
369 a B<-> to turn the option off. Only the first four will normally be used.
375 use the old format. This is equivalent to specifying no name options at all.
379 displays names compatible with RFC2253 equivalent to B<esc_2253>, B<esc_ctrl>,
380 B<esc_msb>, B<utf8>, B<dump_nostr>, B<dump_unknown>, B<dump_der>,
381 B<sep_comma_plus>, B<dn_rev> and B<sname>.
385 a oneline format which is more readable than RFC2253. It is equivalent to
386 specifying the B<esc_2253>, B<esc_ctrl>, B<esc_msb>, B<utf8>, B<dump_nostr>,
387 B<dump_der>, B<use_quote>, B<sep_comma_plus_spc>, B<spc_eq> and B<sname>
392 a multiline format. It is equivalent B<esc_ctrl>, B<esc_msb>, B<sep_multiline>,
393 B<spc_eq> and B<lname>.
397 escape the "special" characters required by RFC2253 in a field That is
398 B<,+"E<lt>E<gt>;>. Additionally B<#> is escaped at the beginnging of a string
399 and a space character at the beginning or end of a string.
403 escape control characters. That is those with ASCII values less than
404 0x20 (space) and the delete (0x7f) character. They are escaped using the
405 RFC2253 \XX notation (where XX are two hex digits representing the
410 escape characters with the MSB set, that is with ASCII values larger than
415 escapes some characters by surrounding the whole string with B<"> characters,
416 without the option all escaping is done with the B<\> character.
420 convert all strings to UTF8 format first. This is required by RFC2253. If
421 you are lucky enough to have a UTF8 compatible terminal then the use
422 of this option (and B<not> setting B<esc_msb>) may result in the correct
423 display of multibyte (international) characters. Is this option is not
424 present then multibyte characters larger than 0xff will be represented
425 using the format \UXXXX for 16 bits and \WXXXXXXXX for 32 bits.
426 Also if this option is off any UTF8Strings will be converted to their
427 character form first.
431 this option does not attempt to interpret multibyte characters in any
432 way. That is their content octets are merely dumped as though one octet
433 represents each character. This is useful for diagnostic purposes but
434 will result in rather odd looking output.
438 show the type of the ASN1 character string. The type precedes the
439 field contents. For example "BMPSTRING: Hello World".
443 when this option is set any fields that need to be hexdumped will
444 be dumped using the DER encoding of the field. Otherwise just the
445 content octets will be displayed. Both options use the RFC2253
450 dump non character string types (for example OCTET STRING) if this
451 option is not set then non character string types will be displayed
452 as though each content octet repesents a single character.
456 dump all fields. This option when used with B<dump_der> allows the
457 DER encoding of the structure to be unambiguously determined.
459 =item B<dump_unknown>
461 dump any field whose OID is not recognised by OpenSSL.
463 =item B<sep_comma_plus>, B<sep_comma_plus_space>, B<sep_semi_plus_space>,
466 these options determine the field separators. The first character is
467 between RDNs and the second between multiple AVAs (multiple AVAs are
468 very rare and their use is discouraged). The options ending in
469 "space" additionally place a space after the separator to make it
470 more readable. The B<sep_multiline> uses a linefeed character for
471 the RDN separator and a spaced B<+> for the AVA separator. It also
472 indents the fields by four characters.
476 reverse the fields of the DN. This is required by RFC2253. As a side
477 effect this also reverses the order of multiple AVAs but this is
480 =item B<nofname>, B<sname>, B<lname>, B<oid>
482 these options alter how the field name is displayed. B<nofname> does
483 not display the field at all. B<sname> uses the "short name" form
484 (CN for commonName for example). B<lname> uses the long form.
485 B<oid> represents the OID in numerical form and is useful for
490 places spaces round the B<=> character which follows the field
495 =head1 OUTPUT OPTIONS
497 As well as customising the name output format, it is also possible to
498 customise the actual fields printed using the B<certopt> options when
499 the B<text> option is present. The default behaviour is to print all fields.
503 use the old format. This is equivalent to specifying no output options at all.
507 don't print header information: that is the lines saying "Certificate" and "Data".
511 don't print out the version number.
515 don't print out the serial number.
519 don't print out the signature algorithm used.
523 don't print the validity, that is the B<notBefore> and B<notAfter> fields.
527 don't print out the subject name.
531 don't print out the issuer name.
535 don't print out the public key.
539 don't give a hexadecimal dump of the certificate signature.
543 don't print out certificate trust information.
545 =item B<no_extensions>
547 don't print out any X509V3 extensions.
551 retain default extension behaviour: attempt to print out unsupported certificate extensions.
555 print an error message for unsupported certificate extensions.
559 ASN1 parse unsupported extensions.
563 hex dump unsupported extensions.
571 Note: in these examples the '\' means the example should be all on one
574 Display the contents of a certificate:
576 openssl x509 -in cert.pem -noout -text
578 Display the certificate serial number:
580 openssl x509 -in cert.pem -noout -serial
582 Display the certificate subject name:
584 openssl x509 -in cert.pem -noout -subject
586 Display the certificate subject name in RFC2253 form:
588 openssl x509 -in cert.pem -noout -subject -nameopt RFC2253
590 Display the certificate subject name in oneline form on a terminal
593 openssl x509 -in cert.pem -noout -subject -nameopt oneline -nameopt -escmsb
595 Display the certificate MD5 fingerprint:
597 openssl x509 -in cert.pem -noout -fingerprint
599 Display the certificate SHA1 fingerprint:
601 openssl x509 -sha1 -in cert.pem -noout -fingerprint
603 Convert a certificate from PEM to DER format:
605 openssl x509 -in cert.pem -inform PEM -out cert.der -outform DER
607 Convert a certificate to a certificate request:
609 openssl x509 -x509toreq -in cert.pem -out req.pem -signkey key.pem
611 Convert a certificate request into a self signed certificate using
614 openssl x509 -req -in careq.pem -extfile openssl.cnf -extensions v3_ca \
615 -signkey key.pem -out cacert.pem
617 Sign a certificate request using the CA certificate above and add user
618 certificate extensions:
620 openssl x509 -req -in req.pem -extfile openssl.cnf -extensions v3_usr \
621 -CA cacert.pem -CAkey key.pem -CAcreateserial
624 Set a certificate to be trusted for SSL client use and change set its alias to
627 openssl x509 -in cert.pem -addtrust sslclient \
628 -alias "Steve's Class 1 CA" -out trust.pem
632 The PEM format uses the header and footer lines:
634 -----BEGIN CERTIFICATE----
635 -----END CERTIFICATE----
637 it will also handle files containing:
639 -----BEGIN X509 CERTIFICATE----
640 -----END X509 CERTIFICATE----
642 Trusted certificates have the lines
644 -----BEGIN TRUSTED CERTIFICATE----
645 -----END TRUSTED CERTIFICATE----
647 The conversion to UTF8 format used with the name options assumes that
648 T61Strings use the ISO8859-1 character set. This is wrong but Netscape
649 and MSIE do this as do many certificates. So although this is incorrect
650 it is more likely to display the majority of certificates correctly.
652 The B<-fingerprint> option takes the digest of the DER encoded certificate.
653 This is commonly called a "fingerprint". Because of the nature of message
654 digests the fingerprint of a certificate is unique to that certificate and
655 two certificates with the same fingerprint can be considered to be the same.
657 The Netscape fingerprint uses MD5 whereas MSIE uses SHA1.
659 The B<-email> option searches the subject name and the subject alternative
660 name extension. Only unique email addresses will be printed out: it will
661 not print the same address more than once.
663 =head1 CERTIFICATE EXTENSIONS
665 The B<-purpose> option checks the certificate extensions and determines
666 what the certificate can be used for. The actual checks done are rather
667 complex and include various hacks and workarounds to handle broken
668 certificates and software.
670 The same code is used when verifying untrusted certificates in chains
671 so this section is useful if a chain is rejected by the verify code.
673 The basicConstraints extension CA flag is used to determine whether the
674 certificate can be used as a CA. If the CA flag is true then it is a CA,
675 if the CA flag is false then it is not a CA. B<All> CAs should have the
678 If the basicConstraints extension is absent then the certificate is
679 considered to be a "possible CA" other extensions are checked according
680 to the intended use of the certificate. A warning is given in this case
681 because the certificate should really not be regarded as a CA: however
682 it is allowed to be a CA to work around some broken software.
684 If the certificate is a V1 certificate (and thus has no extensions) and
685 it is self signed it is also assumed to be a CA but a warning is again
686 given: this is to work around the problem of Verisign roots which are V1
687 self signed certificates.
689 If the keyUsage extension is present then additional restraints are
690 made on the uses of the certificate. A CA certificate B<must> have the
691 keyCertSign bit set if the keyUsage extension is present.
693 The extended key usage extension places additional restrictions on the
694 certificate uses. If this extension is present (whether critical or not)
695 the key can only be used for the purposes specified.
697 A complete description of each test is given below. The comments about
698 basicConstraints and keyUsage and V1 certificates above apply to B<all>
706 The extended key usage extension must be absent or include the "web client
707 authentication" OID. keyUsage must be absent or it must have the
708 digitalSignature bit set. Netscape certificate type must be absent or it must
709 have the SSL client bit set.
711 =item B<SSL Client CA>
713 The extended key usage extension must be absent or include the "web client
714 authentication" OID. Netscape certificate type must be absent or it must have
715 the SSL CA bit set: this is used as a work around if the basicConstraints
720 The extended key usage extension must be absent or include the "web server
721 authentication" and/or one of the SGC OIDs. keyUsage must be absent or it
722 must have the digitalSignature, the keyEncipherment set or both bits set.
723 Netscape certificate type must be absent or have the SSL server bit set.
725 =item B<SSL Server CA>
727 The extended key usage extension must be absent or include the "web server
728 authentication" and/or one of the SGC OIDs. Netscape certificate type must
729 be absent or the SSL CA bit must be set: this is used as a work around if the
730 basicConstraints extension is absent.
732 =item B<Netscape SSL Server>
734 For Netscape SSL clients to connect to an SSL server it must have the
735 keyEncipherment bit set if the keyUsage extension is present. This isn't
736 always valid because some cipher suites use the key for digital signing.
737 Otherwise it is the same as a normal SSL server.
739 =item B<Common S/MIME Client Tests>
741 The extended key usage extension must be absent or include the "email
742 protection" OID. Netscape certificate type must be absent or should have the
743 S/MIME bit set. If the S/MIME bit is not set in netscape certificate type
744 then the SSL client bit is tolerated as an alternative but a warning is shown:
745 this is because some Verisign certificates don't set the S/MIME bit.
747 =item B<S/MIME Signing>
749 In addition to the common S/MIME client tests the digitalSignature bit must
750 be set if the keyUsage extension is present.
752 =item B<S/MIME Encryption>
754 In addition to the common S/MIME tests the keyEncipherment bit must be set
755 if the keyUsage extension is present.
759 The extended key usage extension must be absent or include the "email
760 protection" OID. Netscape certificate type must be absent or must have the
761 S/MIME CA bit set: this is used as a work around if the basicConstraints
766 The keyUsage extension must be absent or it must have the CRL signing bit
769 =item B<CRL Signing CA>
771 The normal CA tests apply. Except in this case the basicConstraints extension
778 Extensions in certificates are not transferred to certificate requests and
781 It is possible to produce invalid certificates or requests by specifying the
782 wrong private key or using inconsistent options in some cases: these should
785 There should be options to explicitly set such things as start and end
786 dates rather than an offset from the current time.
788 The code to implement the verify behaviour described in the B<TRUST SETTINGS>
789 is currently being developed. It thus describes the intended behaviour rather
790 than the current behaviour. It is hoped that it will represent reality in
791 OpenSSL 0.9.5 and later.
795 L<req(1)|req(1)>, L<ca(1)|ca(1)>, L<genrsa(1)|genrsa(1)>,
796 L<gendsa(1)|gendsa(1)>, L<verify(1)|verify(1)>