6 x509 - Certificate display and signing utility
11 [B<-inform DER|PEM|NET>]
12 [B<-outform DER|PEM|NET>]
15 [B<-CAkeyform DER|PEM>]
39 [B<-signkey filename>]
45 [B<-CAserial filename>]
48 [B<-md2|-md5|-sha1|-mdc2>]
50 [B<-extfile filename>]
51 [B<-extensions section>]
55 The B<x509> command is a multi purpose certificate utility. It can be
56 used to display certificate information, convert certificates to
57 various forms, sign certificate requests like a "mini CA" or edit
58 certificate trust settings.
60 Since there are a large number of options they will split up into
64 =head1 INPUT, OUTPUT AND GENERAL PURPOSE OPTIONS
68 =item B<-inform DER|PEM|NET>
70 This specifies the input format normally the command will expect an X509
71 certificate but this can change if other options such as B<-req> are
72 present. The DER format is the DER encoding of the certificate and PEM
73 is the base64 encoding of the DER encoding with header and footer lines
74 added. The NET option is an obscure Netscape server format that is now
77 =item B<-outform DER|PEM|NET>
79 This specifies the output format, the options have the same meaning as the
84 This specifies the input filename to read a certificate from or standard input
85 if this option is not specified.
87 =item B<-out filename>
89 This specifies the output filename to write to or standard output by
92 =item B<-md2|-md5|-sha1|-mdc2>
94 the digest to use. This affects any signing or display option that uses a message
95 digest, such as the B<-fingerprint>, B<-signkey> and B<-CA> options. If not
96 specified then MD5 is used. If the key being used to sign with is a DSA key then
97 this option has no effect: SHA1 is always used with DSA keys.
102 =head1 DISPLAY OPTIONS
104 Note: the B<-alias> and B<-purpose> options are also display options
105 but are described in the B<TRUST OPTIONS> section.
111 prints out the certificate in text form. Full details are output including the
112 public key, signature algorithms, issuer and subject names, serial number
113 any extensions present and any trust settings.
117 this option prevents output of the encoded version of the request.
121 this option prints out the value of the modulus of the public key
122 contained in the certificate.
126 outputs the certificate serial number.
130 outputs the "hash" of the certificate subject name. This is used in OpenSSL to
131 form an index to allow certificates in a directory to be looked up by subject
136 outputs the subject name.
140 outputs the issuer name.
142 =item B<-nameopt option>
144 option which determine how the subject or issuer names are displayed. This
145 option may be used more than once to set multiple options. See the B<NAME
146 OPTIONS> section for more information.
150 outputs the email address(es) if any.
154 prints out the start date of the certificate, that is the notBefore date.
158 prints out the expiry date of the certificate, that is the notAfter date.
162 prints out the start and expiry dates of a certificate.
164 =item B<-fingerprint>
166 prints out the digest of the DER encoded version of the whole certificate
167 (see digest options).
171 this outputs the certificate in the form of a C source file.
175 =head1 TRUST SETTINGS
177 Please note these options are currently experimental and may well change.
179 A B<trusted certificate> is an ordinary certificate which has several
180 additional pieces of information attached to it such as the permitted
181 and prohibited uses of the certificate and an "alias".
183 Normally when a certificate is being verified at least one certificate
184 must be "trusted". By default a trusted certificate must be stored
185 locally and must be a root CA: any certificate chain ending in this CA
186 is then usable for any purpose.
188 Trust settings currently are only used with a root CA. They allow a finer
189 control over the purposes the root CA can be used for. For example a CA
190 may be trusted for SSL client but not SSL server use.
192 See the description of the B<verify> utility for more information on the
193 meaning of trust settings.
195 Future versions of OpenSSL will recognize trust settings on any
196 certificate: not just root CAs.
203 this causes B<x509> to output a B<trusted> certificate. An ordinary
204 or trusted certificate can be input but by default an ordinary
205 certificate is output and any trust settings are discarded. With the
206 B<-trustout> option a trusted certificate is output. A trusted
207 certificate is automatically output if any trust settings are modified.
209 =item B<-setalias arg>
211 sets the alias of the certificate. This will allow the certificate
212 to be referred to using a nickname for example "Steve's Certificate".
216 outputs the certificate alias, if any.
220 clears all the permitted or trusted uses of the certificate.
224 clears all the prohibited or rejected uses of the certificate.
226 =item B<-addtrust arg>
228 adds a trusted certificate use. Any object name can be used here
229 but currently only B<clientAuth> (SSL client use), B<serverAuth>
230 (SSL server use) and B<emailProtection> (S/MIME email) are used.
231 Other OpenSSL applications may define additional uses.
233 =item B<-addreject arg>
235 adds a prohibited use. It accepts the same values as the B<-addtrust>
240 this option performs tests on the certificate extensions and outputs
241 the results. For a more complete description see the B<CERTIFICATE
246 =head1 SIGNING OPTIONS
248 The B<x509> utility can be used to sign certificates and requests: it
249 can thus behave like a "mini CA".
253 =item B<-signkey filename>
255 this option causes the input file to be self signed using the supplied
258 If the input file is a certificate it sets the issuer name to the
259 subject name (i.e. makes it self signed) changes the public key to the
260 supplied value and changes the start and end dates. The start date is
261 set to the current time and the end date is set to a value determined
262 by the B<-days> option. Any certificate extensions are retained unless
263 the B<-clrext> option is supplied.
265 If the input is a certificate request then a self signed certificate
266 is created using the supplied private key using the subject name in
271 delete any extensions from a certificate. This option is used when a
272 certificate is being created from another certificate (for example with
273 the B<-signkey> or the B<-CA> options). Normally all extensions are
276 =item B<-keyform PEM|DER>
278 specifies the format (DER or PEM) of the private key file used in the
283 specifies the number of days to make a certificate valid for. The default
288 converts a certificate into a certificate request. The B<-signkey> option
289 is used to pass the required private key.
293 by default a certificate is expected on input. With this option a
294 certificate request is expected instead.
296 =item B<-CA filename>
298 specifies the CA certificate to be used for signing. When this option is
299 present B<x509> behaves like a "mini CA". The input file is signed by this
300 CA using this option: that is its issuer name is set to the subject name
301 of the CA and it is digitally signed using the CAs private key.
303 This option is normally combined with the B<-req> option. Without the
304 B<-req> option the input is a certificate which must be self signed.
306 =item B<-CAkey filename>
308 sets the CA private key to sign a certificate with. If this option is
309 not specified then it is assumed that the CA private key is present in
310 the CA certificate file.
312 =item B<-CAserial filename>
314 sets the CA serial number file to use.
316 When the B<-CA> option is used to sign a certificate it uses a serial
317 number specified in a file. This file consist of one line containing
318 an even number of hex digits with the serial number to use. After each
319 use the serial number is incremented and written out to the file again.
321 The default filename consists of the CA certificate file base name with
322 ".srl" appended. For example if the CA certificate file is called
323 "mycacert.pem" it expects to find a serial number file called "mycacert.srl".
325 =item B<-CAcreateserial filename>
327 with this option the CA serial number file is created if it does not exist:
328 it will contain the serial number "02" and the certificate being signed will
329 have the 1 as its serial number. Normally if the B<-CA> option is specified
330 and the serial number file does not exist it is an error.
332 =item B<-extfile filename>
334 file containing certificate extensions to use. If not specified then
335 no extensions are added to the certificate.
337 =item B<-extensions section>
339 the section to add certificate extensions from. If this option is not
340 specified then the extensions should either be contained in the unnamed
341 (default) section or the default section should contain a variable called
342 "extensions" which contains the section to use.
348 The B<nameopt> command line switch determines how the subject and issuer
349 names are displayed. If no B<nameopt> switch is present the default "oneline"
350 format is used which is compatible with previous versions of OpenSSL.
351 Each option is described in detail below, all options can be preceded by
352 a B<-> to turn the option off. Only the first four will normally be used.
358 use the old format. This is equivalent to specifying no name options at all.
362 displays names compatible with RFC2253 equivalent to B<esc_2253>, B<esc_ctrl>,
363 B<esc_msb>, B<utf8>, B<dump_nostr>, B<dump_unknown>, B<dump_der>,
364 B<sep_comma_plus>, B<dn_rev> and B<sname>.
368 a oneline format which is more readable than RFC2253. It is equivalent to
369 specifying the B<esc_2253>, B<esc_ctrl>, B<esc_msb>, B<utf8>, B<dump_nostr>,
370 B<dump_der>, B<use_quote>, B<sep_comma_plus_spc>, B<spc_eq> and B<sname>
375 a multiline format. It is equivalent B<esc_ctrl>, B<esc_msb>, B<sep_multiline>,
376 B<spc_eq> and B<lname>.
380 escape the "special" characters required by RFC2253 in a field That is
381 B<,+"E<lt>E<gt>;>. Additionally B<#> is escaped at the beginnging of a string
382 and a space character at the beginning or end of a string.
386 escape control characters. That is those with ASCII values less than
387 0x20 (space) and the delete (0x7f) character. They are escaped using the
388 RFC2253 \XX notation (where XX are two hex digits representing the
393 escape characters with the MSB set, that is with ASCII values larger than
398 escapes some characters by surrounding the whole string with B<"> characters,
399 without the option all escaping is done with the B<\> character.
403 convert all strings to UTF8 format first. This is required by RFC2253. If
404 you are lucky enough to have a UTF8 compatible terminal then the use
405 of this option (and B<not> setting B<esc_msb>) may result in the correct
406 display of multibyte (international) characters. Is this option is not
407 present then multibyte characters larger than 0xff will be represented
408 using the format \UXXXX for 16 bits and \WXXXXXXXX for 32 bits.
409 Also if this option is off any UTF8Strings will be converted to their
410 character form first.
414 this option does not attempt to interpret multibyte characters in any
415 way. That is their content octets are merely dumped as though one octet
416 represents each character. This is useful for diagnostic purposes but
417 will result in rather odd looking output.
421 show the type of the ASN1 character string. The type precedes the
422 field contents. For example "BMPSTRING: Hello World".
426 when this option is set any fields that need to be hexdumped will
427 be dumped using the DER encoding of the field. Otherwise just the
428 content octets will be displayed. Both options use the RFC2253
433 dump non character string types (for example OCTET STRING) if this
434 option is not set then non character string types will be displayed
435 as though each content octet repesents a single character.
439 dump all fields. This option when used with B<dump_der> allows the
440 DER encoding of the structure to be unambiguously determined.
442 =item B<dump_unknown>
444 dump any field whose OID is not recognised by OpenSSL.
446 =item B<sep_comma_plus>, B<sep_comma_plus_space>, B<sep_semi_plus_space>,
449 these options determine the field separators. The first character is
450 between RDNs and the second between multiple AVAs (multiple AVAs are
451 very rare and their use is discouraged). The options ending in
452 "space" additionally place a space after the separator to make it
453 more readable. The B<sep_multiline> uses a linefeed character for
454 the RDN separator and a spaced B<+> for the AVA separator. It also
455 indents the fields by four characters.
459 reverse the fields of the DN. This is required by RFC2253. As a side
460 effect this also reverses the order of multiple AVAs but this is
463 =item B<nofname>, B<sname>, B<lname>, B<oid>
465 these options alter how the field name is displayed. B<nofname> does
466 not display the field at all. B<sname> uses the "short name" form
467 (CN for commonName for example). B<lname> uses the long form.
468 B<oid> represents the OID in numerical form and is useful for
473 places spaces round the B<=> character which follows the field
480 Note: in these examples the '\' means the example should be all on one
483 Display the contents of a certificate:
485 openssl x509 -in cert.pem -noout -text
487 Display the certificate serial number:
489 openssl x509 -in cert.pem -noout -serial
491 Display the certificate subject name:
493 openssl x509 -in cert.pem -noout -subject
495 Display the certificate subject name in RFC2253 form:
497 openssl x509 -in cert.pem -noout -subject -nameopt RFC2253
499 Display the certificate subject name in oneline form on a terminal
502 openssl x509 -in cert.pem -noout -subject -nameopt oneline -nameopt -escmsb
504 Display the certificate MD5 fingerprint:
506 openssl x509 -in cert.pem -noout -fingerprint
508 Display the certificate SHA1 fingerprint:
510 openssl x509 -sha1 -in cert.pem -noout -fingerprint
512 Convert a certificate from PEM to DER format:
514 openssl x509 -in cert.pem -inform PEM -out cert.der -outform DER
516 Convert a certificate to a certificate request:
518 openssl x509 -x509toreq -in cert.pem -out req.pem -signkey key.pem
520 Convert a certificate request into a self signed certificate using
523 openssl x509 -req -in careq.pem -extfile openssl.cnf -extensions v3_ca \
524 -signkey key.pem -out cacert.pem
526 Sign a certificate request using the CA certificate above and add user
527 certificate extensions:
529 openssl x509 -req -in req.pem -extfile openssl.cnf -extensions v3_usr \
530 -CA cacert.pem -CAkey key.pem -CAcreateserial
533 Set a certificate to be trusted for SSL client use and change set its alias to
536 openssl x509 -in cert.pem -addtrust sslclient \
537 -alias "Steve's Class 1 CA" -out trust.pem
541 The PEM format uses the header and footer lines:
543 -----BEGIN CERTIFICATE----
544 -----END CERTIFICATE----
546 it will also handle files containing:
548 -----BEGIN X509 CERTIFICATE----
549 -----END X509 CERTIFICATE----
551 Trusted certificates have the lines
553 -----BEGIN TRUSTED CERTIFICATE----
554 -----END TRUSTED CERTIFICATE----
556 The conversion to UTF8 format used with the name options assumes that
557 T61Strings use the ISO8859-1 character set. This is wrong but Netscape
558 and MSIE do this as do many certificates. So although this is incorrect
559 it is more likely to display the majority of certificates correctly.
561 The B<-fingerprint> option takes the digest of the DER encoded certificate.
562 This is commonly called a "fingerprint". Because of the nature of message
563 digests the fingerprint of a certificate is unique to that certificate and
564 two certificates with the same fingerprint can be considered to be the same.
566 The Netscape fingerprint uses MD5 whereas MSIE uses SHA1.
568 The B<-email> option searches the subject name and the subject alternative
569 name extension. Only unique email addresses will be printed out: it will
570 not print the same address more than once.
572 =head1 CERTIFICATE EXTENSIONS
574 The B<-purpose> option checks the certificate extensions and determines
575 what the certificate can be used for. The actual checks done are rather
576 complex and include various hacks and workarounds to handle broken
577 certificates and software.
579 The same code is used when verifying untrusted certificates in chains
580 so this section is useful if a chain is rejected by the verify code.
582 The basicConstraints extension CA flag is used to determine whether the
583 certificate can be used as a CA. If the CA flag is true then it is a CA,
584 if the CA flag is false then it is not a CA. B<All> CAs should have the
587 If the basicConstraints extension is absent then the certificate is
588 considered to be a "possible CA" other extensions are checked according
589 to the intended use of the certificate. A warning is given in this case
590 because the certificate should really not be regarded as a CA: however
591 it is allowed to be a CA to work around some broken software.
593 If the certificate is a V1 certificate (and thus has no extensions) and
594 it is self signed it is also assumed to be a CA but a warning is again
595 given: this is to work around the problem of Verisign roots which are V1
596 self signed certificates.
598 If the keyUsage extension is present then additional restraints are
599 made on the uses of the certificate. A CA certificate B<must> have the
600 keyCertSign bit set if the keyUsage extension is present.
602 The extended key usage extension places additional restrictions on the
603 certificate uses. If this extension is present (whether critical or not)
604 the key can only be used for the purposes specified.
606 A complete description of each test is given below. The comments about
607 basicConstraints and keyUsage and V1 certificates above apply to B<all>
615 The extended key usage extension must be absent or include the "web client
616 authentication" OID. keyUsage must be absent or it must have the
617 digitalSignature bit set. Netscape certificate type must be absent or it must
618 have the SSL client bit set.
620 =item B<SSL Client CA>
622 The extended key usage extension must be absent or include the "web client
623 authentication" OID. Netscape certificate type must be absent or it must have
624 the SSL CA bit set: this is used as a work around if the basicConstraints
629 The extended key usage extension must be absent or include the "web server
630 authentication" and/or one of the SGC OIDs. keyUsage must be absent or it
631 must have the digitalSignature, the keyEncipherment set or both bits set.
632 Netscape certificate type must be absent or have the SSL server bit set.
634 =item B<SSL Server CA>
636 The extended key usage extension must be absent or include the "web server
637 authentication" and/or one of the SGC OIDs. Netscape certificate type must
638 be absent or the SSL CA bit must be set: this is used as a work around if the
639 basicConstraints extension is absent.
641 =item B<Netscape SSL Server>
643 For Netscape SSL clients to connect to an SSL server it must have the
644 keyEncipherment bit set if the keyUsage extension is present. This isn't
645 always valid because some cipher suites use the key for digital signing.
646 Otherwise it is the same as a normal SSL server.
648 =item B<Common S/MIME Client Tests>
650 The extended key usage extension must be absent or include the "email
651 protection" OID. Netscape certificate type must be absent or should have the
652 S/MIME bit set. If the S/MIME bit is not set in netscape certificate type
653 then the SSL client bit is tolerated as an alternative but a warning is shown:
654 this is because some Verisign certificates don't set the S/MIME bit.
656 =item B<S/MIME Signing>
658 In addition to the common S/MIME client tests the digitalSignature bit must
659 be set if the keyUsage extension is present.
661 =item B<S/MIME Encryption>
663 In addition to the common S/MIME tests the keyEncipherment bit must be set
664 if the keyUsage extension is present.
668 The extended key usage extension must be absent or include the "email
669 protection" OID. Netscape certificate type must be absent or must have the
670 S/MIME CA bit set: this is used as a work around if the basicConstraints
675 The keyUsage extension must be absent or it must have the CRL signing bit
678 =item B<CRL Signing CA>
680 The normal CA tests apply. Except in this case the basicConstraints extension
687 Extensions in certificates are not transferred to certificate requests and
690 It is possible to produce invalid certificates or requests by specifying the
691 wrong private key or using inconsistent options in some cases: these should
694 There should be options to explicitly set such things as start and end
695 dates rather than an offset from the current time.
697 The code to implement the verify behaviour described in the B<TRUST SETTINGS>
698 is currently being developed. It thus describes the intended behaviour rather
699 than the current behaviour. It is hoped that it will represent reality in
700 OpenSSL 0.9.5 and later.
704 L<req(1)|req(1)>, L<ca(1)|ca(1)>, L<genrsa(1)|genrsa(1)>,
705 L<gendsa(1)|gendsa(1)>, L<verify(1)|verify(1)>