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.
118 this option prevents output of the encoded version of the request.
122 this option prints out the value of the modulus of the public key
123 contained in the certificate.
127 outputs the certificate serial number.
131 outputs the "hash" of the certificate subject name. This is used in OpenSSL to
132 form an index to allow certificates in a directory to be looked up by subject
137 outputs the subject name.
141 outputs the issuer name.
143 =item B<-nameopt option>
145 option which determine how the subject or issuer names are displayed. This
146 option may be used more than once to set multiple options. See the B<NAME
147 OPTIONS> section for more information.
151 outputs the email address(es) if any.
155 prints out the start date of the certificate, that is the notBefore date.
159 prints out the expiry date of the certificate, that is the notAfter date.
163 prints out the start and expiry dates of a certificate.
165 =item B<-fingerprint>
167 prints out the digest of the DER encoded version of the whole certificate
168 (see digest options).
172 this outputs the certificate in the form of a C source file.
176 =head1 TRUST SETTINGS
178 Please note these options are currently experimental and may well change.
180 A B<trusted certificate> is an ordinary certificate which has several
181 additional pieces of information attached to it such as the permitted
182 and prohibited uses of the certificate and an "alias".
184 Normally when a certificate is being verified at least one certificate
185 must be "trusted". By default a trusted certificate must be stored
186 locally and must be a root CA: any certificate chain ending in this CA
187 is then usable for any purpose.
189 Trust settings currently are only used with a root CA. They allow a finer
190 control over the purposes the root CA can be used for. For example a CA
191 may be trusted for SSL client but not SSL server use.
193 See the description of the B<verify> utility for more information on the
194 meaning of trust settings.
196 Future versions of OpenSSL will recognize trust settings on any
197 certificate: not just root CAs.
204 this causes B<x509> to output a B<trusted> certificate. An ordinary
205 or trusted certificate can be input but by default an ordinary
206 certificate is output and any trust settings are discarded. With the
207 B<-trustout> option a trusted certificate is output. A trusted
208 certificate is automatically output if any trust settings are modified.
210 =item B<-setalias arg>
212 sets the alias of the certificate. This will allow the certificate
213 to be referred to using a nickname for example "Steve's Certificate".
217 outputs the certificate alias, if any.
221 clears all the permitted or trusted uses of the certificate.
225 clears all the prohibited or rejected uses of the certificate.
227 =item B<-addtrust arg>
229 adds a trusted certificate use. Any object name can be used here
230 but currently only B<clientAuth> (SSL client use), B<serverAuth>
231 (SSL server use) and B<emailProtection> (S/MIME email) are used.
232 Other OpenSSL applications may define additional uses.
234 =item B<-addreject arg>
236 adds a prohibited use. It accepts the same values as the B<-addtrust>
241 this option performs tests on the certificate extensions and outputs
242 the results. For a more complete description see the B<CERTIFICATE
247 =head1 SIGNING OPTIONS
249 The B<x509> utility can be used to sign certificates and requests: it
250 can thus behave like a "mini CA".
254 =item B<-signkey filename>
256 this option causes the input file to be self signed using the supplied
259 If the input file is a certificate it sets the issuer name to the
260 subject name (i.e. makes it self signed) changes the public key to the
261 supplied value and changes the start and end dates. The start date is
262 set to the current time and the end date is set to a value determined
263 by the B<-days> option. Any certificate extensions are retained unless
264 the B<-clrext> option is supplied.
266 If the input is a certificate request then a self signed certificate
267 is created using the supplied private key using the subject name in
272 delete any extensions from a certificate. This option is used when a
273 certificate is being created from another certificate (for example with
274 the B<-signkey> or the B<-CA> options). Normally all extensions are
277 =item B<-keyform PEM|DER>
279 specifies the format (DER or PEM) of the private key file used in the
284 specifies the number of days to make a certificate valid for. The default
289 converts a certificate into a certificate request. The B<-signkey> option
290 is used to pass the required private key.
294 by default a certificate is expected on input. With this option a
295 certificate request is expected instead.
297 =item B<-set_serial n>
299 specifies the serial number to use. This option can be used with either
300 the B<-signkey> or B<-CA> options. If used in conjunction with the B<-CA>
301 option the serial number file (as specified by the B<-CAserial> or
302 B<-CAcreateserial> options) is not used.
304 The serial number can be decimal or hex (if preceded by B<0x>). Negative
305 serial numbers can also be specified but their use is not recommended.
307 =item B<-CA filename>
309 specifies the CA certificate to be used for signing. When this option is
310 present B<x509> behaves like a "mini CA". The input file is signed by this
311 CA using this option: that is its issuer name is set to the subject name
312 of the CA and it is digitally signed using the CAs private key.
314 This option is normally combined with the B<-req> option. Without the
315 B<-req> option the input is a certificate which must be self signed.
317 =item B<-CAkey filename>
319 sets the CA private key to sign a certificate with. If this option is
320 not specified then it is assumed that the CA private key is present in
321 the CA certificate file.
323 =item B<-CAserial filename>
325 sets the CA serial number file to use.
327 When the B<-CA> option is used to sign a certificate it uses a serial
328 number specified in a file. This file consist of one line containing
329 an even number of hex digits with the serial number to use. After each
330 use the serial number is incremented and written out to the file again.
332 The default filename consists of the CA certificate file base name with
333 ".srl" appended. For example if the CA certificate file is called
334 "mycacert.pem" it expects to find a serial number file called "mycacert.srl".
336 =item B<-CAcreateserial filename>
338 with this option the CA serial number file is created if it does not exist:
339 it will contain the serial number "02" and the certificate being signed will
340 have the 1 as its serial number. Normally if the B<-CA> option is specified
341 and the serial number file does not exist it is an error.
343 =item B<-extfile filename>
345 file containing certificate extensions to use. If not specified then
346 no extensions are added to the certificate.
348 =item B<-extensions section>
350 the section to add certificate extensions from. If this option is not
351 specified then the extensions should either be contained in the unnamed
352 (default) section or the default section should contain a variable called
353 "extensions" which contains the section to use.
359 The B<nameopt> command line switch determines how the subject and issuer
360 names are displayed. If no B<nameopt> switch is present the default "oneline"
361 format is used which is compatible with previous versions of OpenSSL.
362 Each option is described in detail below, all options can be preceded by
363 a B<-> to turn the option off. Only the first four will normally be used.
369 use the old format. This is equivalent to specifying no name options at all.
373 displays names compatible with RFC2253 equivalent to B<esc_2253>, B<esc_ctrl>,
374 B<esc_msb>, B<utf8>, B<dump_nostr>, B<dump_unknown>, B<dump_der>,
375 B<sep_comma_plus>, B<dn_rev> and B<sname>.
379 a oneline format which is more readable than RFC2253. It is equivalent to
380 specifying the B<esc_2253>, B<esc_ctrl>, B<esc_msb>, B<utf8>, B<dump_nostr>,
381 B<dump_der>, B<use_quote>, B<sep_comma_plus_spc>, B<spc_eq> and B<sname>
386 a multiline format. It is equivalent B<esc_ctrl>, B<esc_msb>, B<sep_multiline>,
387 B<spc_eq> and B<lname>.
391 escape the "special" characters required by RFC2253 in a field That is
392 B<,+"E<lt>E<gt>;>. Additionally B<#> is escaped at the beginnging of a string
393 and a space character at the beginning or end of a string.
397 escape control characters. That is those with ASCII values less than
398 0x20 (space) and the delete (0x7f) character. They are escaped using the
399 RFC2253 \XX notation (where XX are two hex digits representing the
404 escape characters with the MSB set, that is with ASCII values larger than
409 escapes some characters by surrounding the whole string with B<"> characters,
410 without the option all escaping is done with the B<\> character.
414 convert all strings to UTF8 format first. This is required by RFC2253. If
415 you are lucky enough to have a UTF8 compatible terminal then the use
416 of this option (and B<not> setting B<esc_msb>) may result in the correct
417 display of multibyte (international) characters. Is this option is not
418 present then multibyte characters larger than 0xff will be represented
419 using the format \UXXXX for 16 bits and \WXXXXXXXX for 32 bits.
420 Also if this option is off any UTF8Strings will be converted to their
421 character form first.
425 this option does not attempt to interpret multibyte characters in any
426 way. That is their content octets are merely dumped as though one octet
427 represents each character. This is useful for diagnostic purposes but
428 will result in rather odd looking output.
432 show the type of the ASN1 character string. The type precedes the
433 field contents. For example "BMPSTRING: Hello World".
437 when this option is set any fields that need to be hexdumped will
438 be dumped using the DER encoding of the field. Otherwise just the
439 content octets will be displayed. Both options use the RFC2253
444 dump non character string types (for example OCTET STRING) if this
445 option is not set then non character string types will be displayed
446 as though each content octet repesents a single character.
450 dump all fields. This option when used with B<dump_der> allows the
451 DER encoding of the structure to be unambiguously determined.
453 =item B<dump_unknown>
455 dump any field whose OID is not recognised by OpenSSL.
457 =item B<sep_comma_plus>, B<sep_comma_plus_space>, B<sep_semi_plus_space>,
460 these options determine the field separators. The first character is
461 between RDNs and the second between multiple AVAs (multiple AVAs are
462 very rare and their use is discouraged). The options ending in
463 "space" additionally place a space after the separator to make it
464 more readable. The B<sep_multiline> uses a linefeed character for
465 the RDN separator and a spaced B<+> for the AVA separator. It also
466 indents the fields by four characters.
470 reverse the fields of the DN. This is required by RFC2253. As a side
471 effect this also reverses the order of multiple AVAs but this is
474 =item B<nofname>, B<sname>, B<lname>, B<oid>
476 these options alter how the field name is displayed. B<nofname> does
477 not display the field at all. B<sname> uses the "short name" form
478 (CN for commonName for example). B<lname> uses the long form.
479 B<oid> represents the OID in numerical form and is useful for
484 places spaces round the B<=> character which follows the field
491 Note: in these examples the '\' means the example should be all on one
494 Display the contents of a certificate:
496 openssl x509 -in cert.pem -noout -text
498 Display the certificate serial number:
500 openssl x509 -in cert.pem -noout -serial
502 Display the certificate subject name:
504 openssl x509 -in cert.pem -noout -subject
506 Display the certificate subject name in RFC2253 form:
508 openssl x509 -in cert.pem -noout -subject -nameopt RFC2253
510 Display the certificate subject name in oneline form on a terminal
513 openssl x509 -in cert.pem -noout -subject -nameopt oneline -nameopt -escmsb
515 Display the certificate MD5 fingerprint:
517 openssl x509 -in cert.pem -noout -fingerprint
519 Display the certificate SHA1 fingerprint:
521 openssl x509 -sha1 -in cert.pem -noout -fingerprint
523 Convert a certificate from PEM to DER format:
525 openssl x509 -in cert.pem -inform PEM -out cert.der -outform DER
527 Convert a certificate to a certificate request:
529 openssl x509 -x509toreq -in cert.pem -out req.pem -signkey key.pem
531 Convert a certificate request into a self signed certificate using
534 openssl x509 -req -in careq.pem -extfile openssl.cnf -extensions v3_ca \
535 -signkey key.pem -out cacert.pem
537 Sign a certificate request using the CA certificate above and add user
538 certificate extensions:
540 openssl x509 -req -in req.pem -extfile openssl.cnf -extensions v3_usr \
541 -CA cacert.pem -CAkey key.pem -CAcreateserial
544 Set a certificate to be trusted for SSL client use and change set its alias to
547 openssl x509 -in cert.pem -addtrust sslclient \
548 -alias "Steve's Class 1 CA" -out trust.pem
552 The PEM format uses the header and footer lines:
554 -----BEGIN CERTIFICATE----
555 -----END CERTIFICATE----
557 it will also handle files containing:
559 -----BEGIN X509 CERTIFICATE----
560 -----END X509 CERTIFICATE----
562 Trusted certificates have the lines
564 -----BEGIN TRUSTED CERTIFICATE----
565 -----END TRUSTED CERTIFICATE----
567 The conversion to UTF8 format used with the name options assumes that
568 T61Strings use the ISO8859-1 character set. This is wrong but Netscape
569 and MSIE do this as do many certificates. So although this is incorrect
570 it is more likely to display the majority of certificates correctly.
572 The B<-fingerprint> option takes the digest of the DER encoded certificate.
573 This is commonly called a "fingerprint". Because of the nature of message
574 digests the fingerprint of a certificate is unique to that certificate and
575 two certificates with the same fingerprint can be considered to be the same.
577 The Netscape fingerprint uses MD5 whereas MSIE uses SHA1.
579 The B<-email> option searches the subject name and the subject alternative
580 name extension. Only unique email addresses will be printed out: it will
581 not print the same address more than once.
583 =head1 CERTIFICATE EXTENSIONS
585 The B<-purpose> option checks the certificate extensions and determines
586 what the certificate can be used for. The actual checks done are rather
587 complex and include various hacks and workarounds to handle broken
588 certificates and software.
590 The same code is used when verifying untrusted certificates in chains
591 so this section is useful if a chain is rejected by the verify code.
593 The basicConstraints extension CA flag is used to determine whether the
594 certificate can be used as a CA. If the CA flag is true then it is a CA,
595 if the CA flag is false then it is not a CA. B<All> CAs should have the
598 If the basicConstraints extension is absent then the certificate is
599 considered to be a "possible CA" other extensions are checked according
600 to the intended use of the certificate. A warning is given in this case
601 because the certificate should really not be regarded as a CA: however
602 it is allowed to be a CA to work around some broken software.
604 If the certificate is a V1 certificate (and thus has no extensions) and
605 it is self signed it is also assumed to be a CA but a warning is again
606 given: this is to work around the problem of Verisign roots which are V1
607 self signed certificates.
609 If the keyUsage extension is present then additional restraints are
610 made on the uses of the certificate. A CA certificate B<must> have the
611 keyCertSign bit set if the keyUsage extension is present.
613 The extended key usage extension places additional restrictions on the
614 certificate uses. If this extension is present (whether critical or not)
615 the key can only be used for the purposes specified.
617 A complete description of each test is given below. The comments about
618 basicConstraints and keyUsage and V1 certificates above apply to B<all>
626 The extended key usage extension must be absent or include the "web client
627 authentication" OID. keyUsage must be absent or it must have the
628 digitalSignature bit set. Netscape certificate type must be absent or it must
629 have the SSL client bit set.
631 =item B<SSL Client CA>
633 The extended key usage extension must be absent or include the "web client
634 authentication" OID. Netscape certificate type must be absent or it must have
635 the SSL CA bit set: this is used as a work around if the basicConstraints
640 The extended key usage extension must be absent or include the "web server
641 authentication" and/or one of the SGC OIDs. keyUsage must be absent or it
642 must have the digitalSignature, the keyEncipherment set or both bits set.
643 Netscape certificate type must be absent or have the SSL server bit set.
645 =item B<SSL Server CA>
647 The extended key usage extension must be absent or include the "web server
648 authentication" and/or one of the SGC OIDs. Netscape certificate type must
649 be absent or the SSL CA bit must be set: this is used as a work around if the
650 basicConstraints extension is absent.
652 =item B<Netscape SSL Server>
654 For Netscape SSL clients to connect to an SSL server it must have the
655 keyEncipherment bit set if the keyUsage extension is present. This isn't
656 always valid because some cipher suites use the key for digital signing.
657 Otherwise it is the same as a normal SSL server.
659 =item B<Common S/MIME Client Tests>
661 The extended key usage extension must be absent or include the "email
662 protection" OID. Netscape certificate type must be absent or should have the
663 S/MIME bit set. If the S/MIME bit is not set in netscape certificate type
664 then the SSL client bit is tolerated as an alternative but a warning is shown:
665 this is because some Verisign certificates don't set the S/MIME bit.
667 =item B<S/MIME Signing>
669 In addition to the common S/MIME client tests the digitalSignature bit must
670 be set if the keyUsage extension is present.
672 =item B<S/MIME Encryption>
674 In addition to the common S/MIME tests the keyEncipherment bit must be set
675 if the keyUsage extension is present.
679 The extended key usage extension must be absent or include the "email
680 protection" OID. Netscape certificate type must be absent or must have the
681 S/MIME CA bit set: this is used as a work around if the basicConstraints
686 The keyUsage extension must be absent or it must have the CRL signing bit
689 =item B<CRL Signing CA>
691 The normal CA tests apply. Except in this case the basicConstraints extension
698 Extensions in certificates are not transferred to certificate requests and
701 It is possible to produce invalid certificates or requests by specifying the
702 wrong private key or using inconsistent options in some cases: these should
705 There should be options to explicitly set such things as start and end
706 dates rather than an offset from the current time.
708 The code to implement the verify behaviour described in the B<TRUST SETTINGS>
709 is currently being developed. It thus describes the intended behaviour rather
710 than the current behaviour. It is hoped that it will represent reality in
711 OpenSSL 0.9.5 and later.
715 L<req(1)|req(1)>, L<ca(1)|ca(1)>, L<genrsa(1)|genrsa(1)>,
716 L<gendsa(1)|gendsa(1)>, L<verify(1)|verify(1)>