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135 .\" ========================================================================
136 .\"
137 .IX Title "X509V3_CONFIG 1"
138 .TH X509V3_CONFIG 1 "2014-08-10" "1.0.1n" "OpenSSL"
139 .\" For nroff, turn off justification. Always turn off hyphenation; it makes
140 .\" way too many mistakes in technical documents.
141 .if n .ad l
142 .nh
143 .SH "NAME"
144 x509v3_config \- X509 V3 certificate extension configuration format
145 .SH "DESCRIPTION"
146 .IX Header "DESCRIPTION"
147 Several of the OpenSSL utilities can add extensions to a certificate or
148 certificate request based on the contents of a configuration file.
149 .PP
150 Typically the application will contain an option to point to an extension
151 section. Each line of the extension section takes the form:
152 .PP
153 .Vb 1
154 \& extension_name=[critical,] extension_options
155 .Ve
156 .PP
157 If \fBcritical\fR is present then the extension will be critical.
158 .PP
159 The format of \fBextension_options\fR depends on the value of \fBextension_name\fR.
160 .PP
161 There are four main types of extension: \fIstring\fR extensions, \fImulti-valued\fR
162 extensions, \fIraw\fR and \fIarbitrary\fR extensions.
163 .PP
164 String extensions simply have a string which contains either the value itself
165 or how it is obtained.
166 .PP
167 For example:
168 .PP
169 .Vb 1
170 \& nsComment="This is a Comment"
171 .Ve
172 .PP
173 Multi-valued extensions have a short form and a long form. The short form
174 is a list of names and values:
175 .PP
176 .Vb 1
177 \& basicConstraints=critical,CA:true,pathlen:1
178 .Ve
179 .PP
180 The long form allows the values to be placed in a separate section:
181 .PP
182 .Vb 1
183 \& basicConstraints=critical,@bs_section
184 \&
185 \& [bs_section]
186 \&
187 \& CA=true
188 \& pathlen=1
189 .Ve
190 .PP
191 Both forms are equivalent.
192 .PP
193 The syntax of raw extensions is governed by the extension code: it can
194 for example contain data in multiple sections. The correct syntax to
195 use is defined by the extension code itself: check out the certificate
196 policies extension for an example.
197 .PP
198 If an extension type is unsupported then the \fIarbitrary\fR extension syntax
199 must be used, see the \s-1ARBITRARY EXTENSIONS\s0 section for more details.
200 .SH "STANDARD EXTENSIONS"
201 .IX Header "STANDARD EXTENSIONS"
202 The following sections describe each supported extension in detail.
203 .SS "Basic Constraints."
204 .IX Subsection "Basic Constraints."
205 This is a multi valued extension which indicates whether a certificate is
206 a \s-1CA\s0 certificate. The first (mandatory) name is \fB\s-1CA\s0\fR followed by \fB\s-1TRUE\s0\fR or
207 \&\fB\s-1FALSE\s0\fR. If \fB\s-1CA\s0\fR is \fB\s-1TRUE\s0\fR then an optional \fBpathlen\fR name followed by an
208 non-negative value can be included.
209 .PP
210 For example:
211 .PP
212 .Vb 1
213 \& basicConstraints=CA:TRUE
214 \&
215 \& basicConstraints=CA:FALSE
216 \&
217 \& basicConstraints=critical,CA:TRUE, pathlen:0
218 .Ve
219 .PP
220 A \s-1CA\s0 certificate \fBmust\fR include the basicConstraints value with the \s-1CA\s0 field
221 set to \s-1TRUE.\s0 An end user certificate must either set \s-1CA\s0 to \s-1FALSE\s0 or exclude the
222 extension entirely. Some software may require the inclusion of basicConstraints
223 with \s-1CA\s0 set to \s-1FALSE\s0 for end entity certificates.
224 .PP
225 The pathlen parameter indicates the maximum number of CAs that can appear
226 below this one in a chain. So if you have a \s-1CA\s0 with a pathlen of zero it can
227 only be used to sign end user certificates and not further CAs.
228 .SS "Key Usage."
229 .IX Subsection "Key Usage."
230 Key usage is a multi valued extension consisting of a list of names of the
231 permitted key usages.
232 .PP
233 The supporte names are: digitalSignature, nonRepudiation, keyEncipherment,
234 dataEncipherment, keyAgreement, keyCertSign, cRLSign, encipherOnly
235 and decipherOnly.
236 .PP
237 Examples:
238 .PP
239 .Vb 1
240 \& keyUsage=digitalSignature, nonRepudiation
241 \&
242 \& keyUsage=critical, keyCertSign
243 .Ve
244 .SS "Extended Key Usage."
245 .IX Subsection "Extended Key Usage."
246 This extensions consists of a list of usages indicating purposes for which
247 the certificate public key can be used for,
248 .PP
249 These can either be object short names of the dotted numerical form of OIDs.
250 While any \s-1OID\s0 can be used only certain values make sense. In particular the
251 following \s-1PKIX, NS\s0 and \s-1MS\s0 values are meaningful:
252 .PP
253 .Vb 10
254 \& Value Meaning
255 \& \-\-\-\-\- \-\-\-\-\-\-\-
256 \& serverAuth SSL/TLS Web Server Authentication.
257 \& clientAuth SSL/TLS Web Client Authentication.
258 \& codeSigning Code signing.
259 \& emailProtection E\-mail Protection (S/MIME).
260 \& timeStamping Trusted Timestamping
261 \& msCodeInd Microsoft Individual Code Signing (authenticode)
262 \& msCodeCom Microsoft Commercial Code Signing (authenticode)
263 \& msCTLSign Microsoft Trust List Signing
264 \& msSGC Microsoft Server Gated Crypto
265 \& msEFS Microsoft Encrypted File System
266 \& nsSGC Netscape Server Gated Crypto
267 .Ve
268 .PP
269 Examples:
270 .PP
271 .Vb 2
272 \& extendedKeyUsage=critical,codeSigning,1.2.3.4
273 \& extendedKeyUsage=nsSGC,msSGC
274 .Ve
275 .SS "Subject Key Identifier."
276 .IX Subsection "Subject Key Identifier."
277 This is really a string extension and can take two possible values. Either
278 the word \fBhash\fR which will automatically follow the guidelines in \s-1RFC3280\s0
279 or a hex string giving the extension value to include. The use of the hex
280 string is strongly discouraged.
281 .PP
282 Example:
283 .PP
284 .Vb 1
285 \& subjectKeyIdentifier=hash
286 .Ve
287 .SS "Authority Key Identifier."
288 .IX Subsection "Authority Key Identifier."
289 The authority key identifier extension permits two options. keyid and issuer:
290 both can take the optional value \*(L"always\*(R".
291 .PP
292 If the keyid option is present an attempt is made to copy the subject key
293 identifier from the parent certificate. If the value \*(L"always\*(R" is present
294 then an error is returned if the option fails.
295 .PP
296 The issuer option copies the issuer and serial number from the issuer
297 certificate. This will only be done if the keyid option fails or
298 is not included unless the \*(L"always\*(R" flag will always include the value.
299 .PP
300 Example:
301 .PP
302 .Vb 1
303 \& authorityKeyIdentifier=keyid,issuer
304 .Ve
305 .SS "Subject Alternative Name."
306 .IX Subsection "Subject Alternative Name."
307 The subject alternative name extension allows various literal values to be
308 included in the configuration file. These include \fBemail\fR (an email address)
309 \&\fB\s-1URI\s0\fR a uniform resource indicator, \fB\s-1DNS\s0\fR (a \s-1DNS\s0 domain name), \fB\s-1RID\s0\fR (a
310 registered \s-1ID: OBJECT IDENTIFIER\s0), \fB\s-1IP\s0\fR (an \s-1IP\s0 address), \fBdirName\fR
311 (a distinguished name) and otherName.
312 .PP
313 The email option include a special 'copy' value. This will automatically
314 include and email addresses contained in the certificate subject name in
315 the extension.
316 .PP
317 The \s-1IP\s0 address used in the \fB\s-1IP\s0\fR options can be in either IPv4 or IPv6 format.
318 .PP
319 The value of \fBdirName\fR should point to a section containing the distinguished
320 name to use as a set of name value pairs. Multi values AVAs can be formed by
321 prefacing the name with a \fB+\fR character.
322 .PP
323 otherName can include arbitrary data associated with an \s-1OID:\s0 the value
324 should be the \s-1OID\s0 followed by a semicolon and the content in standard
325 \&\fIASN1_generate_nconf\fR\|(3) format.
326 .PP
327 Examples:
328 .PP
329 .Vb 5
330 \& subjectAltName=email:copy,email:my@other.address,URI:http://my.url.here/
331 \& subjectAltName=IP:192.168.7.1
332 \& subjectAltName=IP:13::17
333 \& subjectAltName=email:my@other.address,RID:1.2.3.4
334 \& subjectAltName=otherName:1.2.3.4;UTF8:some other identifier
335 \&
336 \& subjectAltName=dirName:dir_sect
337 \&
338 \& [dir_sect]
339 \& C=UK
340 \& O=My Organization
341 \& OU=My Unit
342 \& CN=My Name
343 .Ve
344 .SS "Issuer Alternative Name."
345 .IX Subsection "Issuer Alternative Name."
346 The issuer alternative name option supports all the literal options of
347 subject alternative name. It does \fBnot\fR support the email:copy option because
348 that would not make sense. It does support an additional issuer:copy option
349 that will copy all the subject alternative name values from the issuer
350 certificate (if possible).
351 .PP
352 Example:
353 .PP
354 .Vb 1
355 \& issuserAltName = issuer:copy
356 .Ve
357 .SS "Authority Info Access."
358 .IX Subsection "Authority Info Access."
359 The authority information access extension gives details about how to access
360 certain information relating to the \s-1CA.\s0 Its syntax is accessOID;location
361 where \fIlocation\fR has the same syntax as subject alternative name (except
362 that email:copy is not supported). accessOID can be any valid \s-1OID\s0 but only
363 certain values are meaningful, for example \s-1OCSP\s0 and caIssuers.
364 .PP
365 Example:
366 .PP
367 .Vb 2
368 \& authorityInfoAccess = OCSP;URI:http://ocsp.my.host/
369 \& authorityInfoAccess = caIssuers;URI:http://my.ca/ca.html
370 .Ve
371 .SS "\s-1CRL\s0 distribution points."
372 .IX Subsection "CRL distribution points."
373 This is a multi-valued extension whose options can be either in name:value pair
374 using the same form as subject alternative name or a single value representing
375 a section name containing all the distribution point fields.
376 .PP
377 For a name:value pair a new DistributionPoint with the fullName field set to
378 the given value both the cRLissuer and reasons fields are omitted in this case.
379 .PP
380 In the single option case the section indicated contains values for each
381 field. In this section:
382 .PP
383 If the name is \*(L"fullname\*(R" the value field should contain the full name
384 of the distribution point in the same format as subject alternative name.
385 .PP
386 If the name is \*(L"relativename\*(R" then the value field should contain a section
387 name whose contents represent a \s-1DN\s0 fragment to be placed in this field.
388 .PP
389 The name \*(L"CRLIssuer\*(R" if present should contain a value for this field in
390 subject alternative name format.
391 .PP
392 If the name is \*(L"reasons\*(R" the value field should consist of a comma
393 separated field containing the reasons. Valid reasons are: \*(L"keyCompromise\*(R",
394 \&\*(L"CACompromise\*(R", \*(L"affiliationChanged\*(R", \*(L"superseded\*(R", \*(L"cessationOfOperation\*(R",
395 \&\*(L"certificateHold\*(R", \*(L"privilegeWithdrawn\*(R" and \*(L"AACompromise\*(R".
396 .PP
397 Simple examples:
398 .PP
399 .Vb 2
400 \& crlDistributionPoints=URI:http://myhost.com/myca.crl
401 \& crlDistributionPoints=URI:http://my.com/my.crl,URI:http://oth.com/my.crl
402 .Ve
403 .PP
404 Full distribution point example:
405 .PP
406 .Vb 1
407 \& crlDistributionPoints=crldp1_section
408 \&
409 \& [crldp1_section]
410 \&
411 \& fullname=URI:http://myhost.com/myca.crl
412 \& CRLissuer=dirName:issuer_sect
413 \& reasons=keyCompromise, CACompromise
414 \&
415 \& [issuer_sect]
416 \& C=UK
417 \& O=Organisation
418 \& CN=Some Name
419 .Ve
420 .SS "Issuing Distribution Point"
421 .IX Subsection "Issuing Distribution Point"
422 This extension should only appear in CRLs. It is a multi valued extension
423 whose syntax is similar to the \*(L"section\*(R" pointed to by the \s-1CRL\s0 distribution
424 points extension with a few differences.
425 .PP
426 The names \*(L"reasons\*(R" and \*(L"CRLissuer\*(R" are not recognized.
427 .PP
428 The name \*(L"onlysomereasons\*(R" is accepted which sets this field. The value is
429 in the same format as the \s-1CRL\s0 distribution point \*(L"reasons\*(R" field.
430 .PP
431 The names \*(L"onlyuser\*(R", \*(L"onlyCA\*(R", \*(L"onlyAA\*(R" and \*(L"indirectCRL\*(R" are also accepted
432 the values should be a boolean value (\s-1TRUE\s0 or \s-1FALSE\s0) to indicate the value of
433 the corresponding field.
434 .PP
435 Example:
436 .PP
437 .Vb 1
438 \& issuingDistributionPoint=critical, @idp_section
439 \&
440 \& [idp_section]
441 \&
442 \& fullname=URI:http://myhost.com/myca.crl
443 \& indirectCRL=TRUE
444 \& onlysomereasons=keyCompromise, CACompromise
445 \&
446 \& [issuer_sect]
447 \& C=UK
448 \& O=Organisation
449 \& CN=Some Name
450 .Ve
451 .SS "Certificate Policies."
452 .IX Subsection "Certificate Policies."
453 This is a \fIraw\fR extension. All the fields of this extension can be set by
454 using the appropriate syntax.
455 .PP
456 If you follow the \s-1PKIX\s0 recommendations and just using one \s-1OID\s0 then you just
457 include the value of that \s-1OID.\s0 Multiple OIDs can be set separated by commas,
458 for example:
459 .PP
460 .Vb 1
461 \& certificatePolicies= 1.2.4.5, 1.1.3.4
462 .Ve
463 .PP
464 If you wish to include qualifiers then the policy \s-1OID\s0 and qualifiers need to
465 be specified in a separate section: this is done by using the \f(CW@section\fR syntax
466 instead of a literal \s-1OID\s0 value.
467 .PP
468 The section referred to must include the policy \s-1OID\s0 using the name
469 policyIdentifier, cPSuri qualifiers can be included using the syntax:
470 .PP
471 .Vb 1
472 \& CPS.nnn=value
473 .Ve
474 .PP
475 userNotice qualifiers can be set using the syntax:
476 .PP
477 .Vb 1
478 \& userNotice.nnn=@notice
479 .Ve
480 .PP
481 The value of the userNotice qualifier is specified in the relevant section.
482 This section can include explicitText, organization and noticeNumbers
483 options. explicitText and organization are text strings, noticeNumbers is a
484 comma separated list of numbers. The organization and noticeNumbers options
485 (if included) must \s-1BOTH\s0 be present. If you use the userNotice option with \s-1IE5\s0
486 then you need the 'ia5org' option at the top level to modify the encoding:
487 otherwise it will not be interpreted properly.
488 .PP
489 Example:
490 .PP
491 .Vb 1
492 \& certificatePolicies=ia5org,1.2.3.4,1.5.6.7.8,@polsect
493 \&
494 \& [polsect]
495 \&
496 \& policyIdentifier = 1.3.5.8
497 \& CPS.1="http://my.host.name/"
498 \& CPS.2="http://my.your.name/"
499 \& userNotice.1=@notice
500 \&
501 \& [notice]
502 \&
503 \& explicitText="Explicit Text Here"
504 \& organization="Organisation Name"
505 \& noticeNumbers=1,2,3,4
506 .Ve
507 .PP
508 The \fBia5org\fR option changes the type of the \fIorganization\fR field. In \s-1RFC2459\s0
509 it can only be of type DisplayText. In \s-1RFC3280\s0 IA5Strring is also permissible.
510 Some software (for example some versions of \s-1MSIE\s0) may require ia5org.
511 .SS "Policy Constraints"
512 .IX Subsection "Policy Constraints"
513 This is a multi-valued extension which consisting of the names
514 \&\fBrequireExplicitPolicy\fR or \fBinhibitPolicyMapping\fR and a non negative intger
515 value. At least one component must be present.
516 .PP
517 Example:
518 .PP
519 .Vb 1
520 \& policyConstraints = requireExplicitPolicy:3
521 .Ve
522 .SS "Inhibit Any Policy"
523 .IX Subsection "Inhibit Any Policy"
524 This is a string extension whose value must be a non negative integer.
525 .PP
526 Example:
527 .PP
528 .Vb 1
529 \& inhibitAnyPolicy = 2
530 .Ve
531 .SS "Name Constraints"
532 .IX Subsection "Name Constraints"
533 The name constraints extension is a multi-valued extension. The name should
534 begin with the word \fBpermitted\fR or \fBexcluded\fR followed by a \fB;\fR. The rest of
535 the name and the value follows the syntax of subjectAltName except email:copy
536 is not supported and the \fB\s-1IP\s0\fR form should consist of an \s-1IP\s0 addresses and
537 subnet mask separated by a \fB/\fR.
538 .PP
539 Examples:
540 .PP
541 .Vb 1
542 \& nameConstraints=permitted;IP:192.168.0.0/255.255.0.0
543 \&
544 \& nameConstraints=permitted;email:.somedomain.com
545 \&
546 \& nameConstraints=excluded;email:.com
547 .Ve
548 .SS "\s-1OCSP\s0 No Check"
549 .IX Subsection "OCSP No Check"
550 The \s-1OCSP\s0 No Check extension is a string extension but its value is ignored.
551 .PP
552 Example:
553 .PP
554 .Vb 1
555 \& noCheck = ignored
556 .Ve
557 .SH "DEPRECATED EXTENSIONS"
558 .IX Header "DEPRECATED EXTENSIONS"
559 The following extensions are non standard, Netscape specific and largely
560 obsolete. Their use in new applications is discouraged.
561 .SS "Netscape String extensions."
562 .IX Subsection "Netscape String extensions."
563 Netscape Comment (\fBnsComment\fR) is a string extension containing a comment
564 which will be displayed when the certificate is viewed in some browsers.
565 .PP
566 Example:
567 .PP
568 .Vb 1
569 \& nsComment = "Some Random Comment"
570 .Ve
571 .PP
572 Other supported extensions in this category are: \fBnsBaseUrl\fR,
573 \&\fBnsRevocationUrl\fR, \fBnsCaRevocationUrl\fR, \fBnsRenewalUrl\fR, \fBnsCaPolicyUrl\fR
574 and \fBnsSslServerName\fR.
575 .SS "Netscape Certificate Type"
576 .IX Subsection "Netscape Certificate Type"
577 This is a multi-valued extensions which consists of a list of flags to be
578 included. It was used to indicate the purposes for which a certificate could
579 be used. The basicConstraints, keyUsage and extended key usage extensions are
580 now used instead.
581 .PP
582 Acceptable values for nsCertType are: \fBclient\fR, \fBserver\fR, \fBemail\fR,
583 \&\fBobjsign\fR, \fBreserved\fR, \fBsslCA\fR, \fBemailCA\fR, \fBobjCA\fR.
584 .SH "ARBITRARY EXTENSIONS"
585 .IX Header "ARBITRARY EXTENSIONS"
586 If an extension is not supported by the OpenSSL code then it must be encoded
587 using the arbitrary extension format. It is also possible to use the arbitrary
588 format for supported extensions. Extreme care should be taken to ensure that
589 the data is formatted correctly for the given extension type.
590 .PP
591 There are two ways to encode arbitrary extensions.
592 .PP
593 The first way is to use the word \s-1ASN1\s0 followed by the extension content
594 using the same syntax as \fIASN1_generate_nconf\fR\|(3).
595 For example:
596 .PP
597 .Vb 1
598 \& 1.2.3.4=critical,ASN1:UTF8String:Some random data
599 \&
600 \& 1.2.3.4=ASN1:SEQUENCE:seq_sect
601 \&
602 \& [seq_sect]
603 \&
604 \& field1 = UTF8:field1
605 \& field2 = UTF8:field2
606 .Ve
607 .PP
608 It is also possible to use the word \s-1DER\s0 to include the raw encoded data in any
609 extension.
610 .PP
611 .Vb 2
612 \& 1.2.3.4=critical,DER:01:02:03:04
613 \& 1.2.3.4=DER:01020304
614 .Ve
615 .PP
616 The value following \s-1DER\s0 is a hex dump of the \s-1DER\s0 encoding of the extension
617 Any extension can be placed in this form to override the default behaviour.
618 For example:
619 .PP
620 .Vb 1
621 \& basicConstraints=critical,DER:00:01:02:03
622 .Ve
623 .SH "WARNING"
624 .IX Header "WARNING"
625 There is no guarantee that a specific implementation will process a given
626 extension. It may therefore be sometimes possible to use certificates for
627 purposes prohibited by their extensions because a specific application does
628 not recognize or honour the values of the relevant extensions.
629 .PP
630 The \s-1DER\s0 and \s-1ASN1\s0 options should be used with caution. It is possible to create
631 totally invalid extensions if they are not used carefully.
632 .SH "NOTES"
633 .IX Header "NOTES"
634 If an extension is multi-value and a field value must contain a comma the long
635 form must be used otherwise the comma would be misinterpreted as a field
636 separator. For example:
637 .PP
638 .Vb 1
639 \& subjectAltName=URI:ldap://somehost.com/CN=foo,OU=bar
640 .Ve
641 .PP
642 will produce an error but the equivalent form:
643 .PP
644 .Vb 1
645 \& subjectAltName=@subject_alt_section
646 \&
647 \& [subject_alt_section]
648 \& subjectAltName=URI:ldap://somehost.com/CN=foo,OU=bar
649 .Ve
650 .PP
651 is valid.
652 .PP
653 Due to the behaviour of the OpenSSL \fBconf\fR library the same field name
654 can only occur once in a section. This means that:
655 .PP
656 .Vb 1
657 \& subjectAltName=@alt_section
658 \&
659 \& [alt_section]
660 \&
661 \& email=steve@here
662 \& email=steve@there
663 .Ve
664 .PP
665 will only recognize the last value. This can be worked around by using the form:
666 .PP
667 .Vb 1
668 \& [alt_section]
669 \&
670 \& email.1=steve@here
671 \& email.2=steve@there
672 .Ve
673 .SH "HISTORY"
674 .IX Header "HISTORY"
675 The X509v3 extension code was first added to OpenSSL 0.9.2.
676 .PP
677 Policy mappings, inhibit any policy and name constraints support was added in
678 OpenSSL 0.9.8
679 .PP
680 The \fBdirectoryName\fR and \fBotherName\fR option as well as the \fB\s-1ASN1\s0\fR option
681 for arbitrary extensions was added in OpenSSL 0.9.8
682 .SH "SEE ALSO"
683 .IX Header "SEE ALSO"
684 \&\fIopenssl_req\fR\|(1), \fIopenssl_ca\fR\|(1), \fIopenssl_x509\fR\|(1),
685 \&\fIASN1_generate_nconf\fR\|(3)