doc/man5/x509v3_config.pod - third_party/openssl - Git at Google

 =pod

 =head1 NAME

 x509v3_config - X509 V3 certificate extension configuration format

 =head1 DESCRIPTION

 Several of the OpenSSL utilities can add extensions to a certificate or
 certificate request based on the contents of a configuration file.

 Typically the application will contain an option to point to an extension
 section. Each line of the extension section takes the form:

  extension_name=[critical,] extension_options

 If B<critical> is present then the extension will be critical.

 The format of B<extension_options> depends on the value of B<extension_name>.

 There are four main types of extension: I<string> extensions, I<multi-valued>
 extensions, I<raw> and I<arbitrary> extensions.

 String extensions simply have a string which contains either the value itself
 or how it is obtained.

 For example:

  nsComment="This is a Comment"

 Multi-valued extensions have a short form and a long form. The short form
 is a list of names and values:

  basicConstraints=critical,CA:true,pathlen:1

 The long form allows the values to be placed in a separate section:

  basicConstraints=critical,@bs_section

  [bs_section]

  CA=true
  pathlen=1

 Both forms are equivalent.

 The syntax of raw extensions is governed by the extension code: it can
 for example contain data in multiple sections. The correct syntax to
 use is defined by the extension code itself: check out the certificate
 policies extension for an example.

 If an extension type is unsupported then the I<arbitrary> extension syntax
 must be used, see the L<ARBITRARY EXTENSIONS|/"ARBITRARY EXTENSIONS"> section for more details.

 =head1 STANDARD EXTENSIONS

 The following sections describe each supported extension in detail.

 =head2 Basic Constraints.

 This is a multi valued extension which indicates whether a certificate is
 a CA certificate. The first (mandatory) name is B<CA> followed by B<TRUE> or
 B<FALSE>. If B<CA> is B<TRUE> then an optional B<pathlen> name followed by an
 non-negative value can be included.

 For example:

  basicConstraints=CA:TRUE

  basicConstraints=CA:FALSE

  basicConstraints=critical,CA:TRUE, pathlen:0

 A CA certificate B<must> include the basicConstraints value with the CA field
 set to TRUE. An end user certificate must either set CA to FALSE or exclude the
 extension entirely. Some software may require the inclusion of basicConstraints
 with CA set to FALSE for end entity certificates.

 The pathlen parameter indicates the maximum number of CAs that can appear
 below this one in a chain. So if you have a CA with a pathlen of zero it can
 only be used to sign end user certificates and not further CAs.


 =head2 Key Usage.

 Key usage is a multi valued extension consisting of a list of names of the
 permitted key usages.

 The supported names are: digitalSignature, nonRepudiation, keyEncipherment,
 dataEncipherment, keyAgreement, keyCertSign, cRLSign, encipherOnly
 and decipherOnly.

 Examples:

  keyUsage=digitalSignature, nonRepudiation

  keyUsage=critical, keyCertSign


 =head2 Extended Key Usage.

 This extensions consists of a list of usages indicating purposes for which
 the certificate public key can be used for,

 These can either be object short names or the dotted numerical form of OIDs.
 While any OID can be used only certain values make sense. In particular the
 following PKIX, NS and MS values are meaningful:

  Value                  Meaning
  -----                  -------
  serverAuth             SSL/TLS Web Server Authentication.
  clientAuth             SSL/TLS Web Client Authentication.
  codeSigning            Code signing.
  emailProtection        E-mail Protection (S/MIME).
  timeStamping           Trusted Timestamping
  OCSPSigning            OCSP Signing
  ipsecIKE               ipsec Internet Key Exchange
  msCodeInd              Microsoft Individual Code Signing (authenticode)
  msCodeCom              Microsoft Commercial Code Signing (authenticode)
  msCTLSign              Microsoft Trust List Signing
  msEFS                  Microsoft Encrypted File System

 Examples:

  extendedKeyUsage=critical,codeSigning,1.2.3.4
  extendedKeyUsage=serverAuth,clientAuth


 =head2 Subject Key Identifier.

 This is really a string extension and can take two possible values. Either
 the word B<hash> which will automatically follow the guidelines in RFC3280
 or a hex string giving the extension value to include. The use of the hex
 string is strongly discouraged.

 Example:

  subjectKeyIdentifier=hash


 =head2 Authority Key Identifier.

 The authority key identifier extension permits two options. keyid and issuer:
 both can take the optional value "always".

 If the keyid option is present an attempt is made to copy the subject key
 identifier from the parent certificate. If the value "always" is present
 then an error is returned if the option fails.

 The issuer option copies the issuer and serial number from the issuer
 certificate. This will only be done if the keyid option fails or
 is not included unless the "always" flag will always include the value.

 Example:

  authorityKeyIdentifier=keyid,issuer


 =head2 Subject Alternative Name.

 The subject alternative name extension allows various literal values to be
 included in the configuration file. These include B<email> (an email address)
 B<URI> a uniform resource indicator, B<DNS> (a DNS domain name), B<RID> (a
 registered ID: OBJECT IDENTIFIER), B<IP> (an IP address), B<dirName>
 (a distinguished name) and otherName.

 The email option include a special 'copy' value. This will automatically
 include and email addresses contained in the certificate subject name in
 the extension.

 The IP address used in the B<IP> options can be in either IPv4 or IPv6 format.

 The value of B<dirName> should point to a section containing the distinguished
 name to use as a set of name value pairs. Multi values AVAs can be formed by
 prefacing the name with a B<+> character.

 otherName can include arbitrary data associated with an OID: the value
 should be the OID followed by a semicolon and the content in standard
 L<ASN1_generate_nconf(3)> format.

 Examples:

  subjectAltName=email:copy,email:my@other.address,URI:http://my.url.here/
  subjectAltName=IP:192.168.7.1
  subjectAltName=IP:13::17
  subjectAltName=email:my@other.address,RID:1.2.3.4
  subjectAltName=otherName:1.2.3.4;UTF8:some other identifier

  subjectAltName=dirName:dir_sect

  [dir_sect]
  C=UK
  O=My Organization
  OU=My Unit
  CN=My Name


 =head2 Issuer Alternative Name.

 The issuer alternative name option supports all the literal options of
 subject alternative name. It does B<not> support the email:copy option because
 that would not make sense. It does support an additional issuer:copy option
 that will copy all the subject alternative name values from the issuer
 certificate (if possible).

 Example:

  issuserAltName = issuer:copy


 =head2 Authority Info Access.

 The authority information access extension gives details about how to access
 certain information relating to the CA. Its syntax is accessOID;location
 where I<location> has the same syntax as subject alternative name (except
 that email:copy is not supported). accessOID can be any valid OID but only
 certain values are meaningful, for example OCSP and caIssuers.

 Example:

  authorityInfoAccess = OCSP;URI:http://ocsp.my.host/
  authorityInfoAccess = caIssuers;URI:http://my.ca/ca.html


 =head2 CRL distribution points

 This is a multi-valued extension whose options can be either in name:value pair
 using the same form as subject alternative name or a single value representing
 a section name containing all the distribution point fields.

 For a name:value pair a new DistributionPoint with the fullName field set to
 the given value both the cRLissuer and reasons fields are omitted in this case.

 In the single option case the section indicated contains values for each
 field. In this section:

 If the name is "fullname" the value field should contain the full name
 of the distribution point in the same format as subject alternative name.

 If the name is "relativename" then the value field should contain a section
 name whose contents represent a DN fragment to be placed in this field.

 The name "CRLIssuer" if present should contain a value for this field in
 subject alternative name format.

 If the name is "reasons" the value field should consist of a comma
 separated field containing the reasons. Valid reasons are: "keyCompromise",
 "CACompromise", "affiliationChanged", "superseded", "cessationOfOperation",
 "certificateHold", "privilegeWithdrawn" and "AACompromise".


 Simple examples:

  crlDistributionPoints=URI:http://myhost.com/myca.crl
  crlDistributionPoints=URI:http://my.com/my.crl,URI:http://oth.com/my.crl

 Full distribution point example:

  crlDistributionPoints=crldp1_section

  [crldp1_section]

  fullname=URI:http://myhost.com/myca.crl
  CRLissuer=dirName:issuer_sect
  reasons=keyCompromise, CACompromise

  [issuer_sect]
  C=UK
  O=Organisation
  CN=Some Name

 =head2 Issuing Distribution Point

 This extension should only appear in CRLs. It is a multi valued extension
 whose syntax is similar to the "section" pointed to by the CRL distribution
 points extension with a few differences.

 The names "reasons" and "CRLissuer" are not recognized.

 The name "onlysomereasons" is accepted which sets this field. The value is
 in the same format as the CRL distribution point "reasons" field.

 The names "onlyuser", "onlyCA", "onlyAA" and "indirectCRL" are also accepted
 the values should be a boolean value (TRUE or FALSE) to indicate the value of
 the corresponding field.

 Example:

  issuingDistributionPoint=critical, @idp_section

  [idp_section]

  fullname=URI:http://myhost.com/myca.crl
  indirectCRL=TRUE
  onlysomereasons=keyCompromise, CACompromise

  [issuer_sect]
  C=UK
  O=Organisation
  CN=Some Name


 =head2 Certificate Policies.

 This is a I<raw> extension. All the fields of this extension can be set by
 using the appropriate syntax.

 If you follow the PKIX recommendations and just using one OID then you just
 include the value of that OID. Multiple OIDs can be set separated by commas,
 for example:

  certificatePolicies= 1.2.4.5, 1.1.3.4

 If you wish to include qualifiers then the policy OID and qualifiers need to
 be specified in a separate section: this is done by using the @section syntax
 instead of a literal OID value.

 The section referred to must include the policy OID using the name
 policyIdentifier, cPSuri qualifiers can be included using the syntax:

  CPS.nnn=value

 userNotice qualifiers can be set using the syntax:

  userNotice.nnn=@notice

 The value of the userNotice qualifier is specified in the relevant section.
 This section can include explicitText, organization and noticeNumbers
 options. explicitText and organization are text strings, noticeNumbers is a
 comma separated list of numbers. The organization and noticeNumbers options
 (if included) must BOTH be present. If you use the userNotice option with IE5
 then you need the 'ia5org' option at the top level to modify the encoding:
 otherwise it will not be interpreted properly.

 Example:

  certificatePolicies=ia5org,1.2.3.4,1.5.6.7.8,@polsect

  [polsect]

  policyIdentifier = 1.3.5.8
  CPS.1="http://my.host.name/"
  CPS.2="http://my.your.name/"
  userNotice.1=@notice

  [notice]

  explicitText="Explicit Text Here"
  organization="Organisation Name"
  noticeNumbers=1,2,3,4

 The B<ia5org> option changes the type of the I<organization> field. In RFC2459
 it can only be of type DisplayText. In RFC3280 IA5Strring is also permissible.
 Some software (for example some versions of MSIE) may require ia5org.

 =head2 Policy Constraints

 This is a multi-valued extension which consisting of the names
 B<requireExplicitPolicy> or B<inhibitPolicyMapping> and a non negative integer
 value. At least one component must be present.

 Example:

  policyConstraints = requireExplicitPolicy:3


 =head2 Inhibit Any Policy

 This is a string extension whose value must be a non negative integer.

 Example:

  inhibitAnyPolicy = 2


 =head2 Name Constraints

 The name constraints extension is a multi-valued extension. The name should
 begin with the word B<permitted> or B<excluded> followed by a B<;>. The rest of
 the name and the value follows the syntax of subjectAltName except email:copy
 is not supported and the B<IP> form should consist of an IP addresses and
 subnet mask separated by a B</>.

 Examples:

  nameConstraints=permitted;IP:192.168.0.0/255.255.0.0

  nameConstraints=permitted;email:.somedomain.com

  nameConstraints=excluded;email:.com


 =head2 OCSP No Check

 The OCSP No Check extension is a string extension but its value is ignored.

 Example:

  noCheck = ignored


 =head2 TLS Feature (aka Must Staple)

 This is a multi-valued extension consisting of a list of TLS extension
 identifiers. Each identifier may be a number (0..65535) or a supported name.
 When a TLS client sends a listed extension, the TLS server is expected to
 include that extension in its reply.

 The supported names are: B<status_request> and B<status_request_v2>.

 Example:

  tlsfeature = status_request


 =head1 DEPRECATED EXTENSIONS

 The following extensions are non standard, Netscape specific and largely
 obsolete. Their use in new applications is discouraged.

 =head2 Netscape String extensions.

 Netscape Comment (B<nsComment>) is a string extension containing a comment
 which will be displayed when the certificate is viewed in some browsers.

 Example:

  nsComment = "Some Random Comment"

 Other supported extensions in this category are: B<nsBaseUrl>,
 B<nsRevocationUrl>, B<nsCaRevocationUrl>, B<nsRenewalUrl>, B<nsCaPolicyUrl>
 and B<nsSslServerName>.


 =head2 Netscape Certificate Type

 This is a multi-valued extensions which consists of a list of flags to be
 included. It was used to indicate the purposes for which a certificate could
 be used. The basicConstraints, keyUsage and extended key usage extensions are
 now used instead.

 Acceptable values for nsCertType are: B<client>, B<server>, B<email>,
 B<objsign>, B<reserved>, B<sslCA>, B<emailCA>, B<objCA>.


 =head1 ARBITRARY EXTENSIONS

 If an extension is not supported by the OpenSSL code then it must be encoded
 using the arbitrary extension format. It is also possible to use the arbitrary
 format for supported extensions. Extreme care should be taken to ensure that
 the data is formatted correctly for the given extension type.

 There are two ways to encode arbitrary extensions.

 The first way is to use the word ASN1 followed by the extension content
 using the same syntax as L<ASN1_generate_nconf(3)>.
 For example:

  1.2.3.4=critical,ASN1:UTF8String:Some random data

  1.2.3.4=ASN1:SEQUENCE:seq_sect

  [seq_sect]

  field1 = UTF8:field1
  field2 = UTF8:field2

 It is also possible to use the word DER to include the raw encoded data in any
 extension.

  1.2.3.4=critical,DER:01:02:03:04
  1.2.3.4=DER:01020304

 The value following DER is a hex dump of the DER encoding of the extension
 Any extension can be placed in this form to override the default behaviour.
 For example:

  basicConstraints=critical,DER:00:01:02:03

 =head1 WARNING

 There is no guarantee that a specific implementation will process a given
 extension. It may therefore be sometimes possible to use certificates for
 purposes prohibited by their extensions because a specific application does
 not recognize or honour the values of the relevant extensions.

 The DER and ASN1 options should be used with caution. It is possible to create
 totally invalid extensions if they are not used carefully.


 =head1 NOTES

 If an extension is multi-value and a field value must contain a comma the long
 form must be used otherwise the comma would be misinterpreted as a field
 separator. For example:

  subjectAltName=URI:ldap://somehost.com/CN=foo,OU=bar

 will produce an error but the equivalent form:

  subjectAltName=@subject_alt_section

  [subject_alt_section]
  subjectAltName=URI:ldap://somehost.com/CN=foo,OU=bar

 is valid.

 Due to the behaviour of the OpenSSL B<conf> library the same field name
 can only occur once in a section. This means that:

  subjectAltName=@alt_section

  [alt_section]

  email=steve@here
  email=steve@there

 will only recognize the last value. This can be worked around by using the form:

  [alt_section]

  email.1=steve@here
  email.2=steve@there

 =head1 SEE ALSO

 L<req(1)>, L<ca(1)>, L<x509(1)>,
 L<ASN1_generate_nconf(3)>

 =head1 COPYRIGHT

 Copyright 2004-2016 The OpenSSL Project Authors. All Rights Reserved.

 Licensed under the OpenSSL license (the "License").  You may not use
 this file except in compliance with the License.  You can obtain a copy
 in the file LICENSE in the source distribution or at
 L<https://www.openssl.org/source/license.html>.

 =cut
	=pod

	=head1 NAME

	x509v3_config - X509 V3 certificate extension configuration format

	=head1 DESCRIPTION

	Several of the OpenSSL utilities can add extensions to a certificate or
	certificate request based on the contents of a configuration file.

	Typically the application will contain an option to point to an extension
	section. Each line of the extension section takes the form:

	extension_name=[critical,] extension_options

	If B<critical> is present then the extension will be critical.

	The format of B<extension_options> depends on the value of B<extension_name>.

	There are four main types of extension: I<string> extensions, I<multi-valued>
	extensions, I<raw> and I<arbitrary> extensions.

	String extensions simply have a string which contains either the value itself
	or how it is obtained.

	For example:

	nsComment="This is a Comment"

	Multi-valued extensions have a short form and a long form. The short form
	is a list of names and values:

	basicConstraints=critical,CA:true,pathlen:1

	The long form allows the values to be placed in a separate section:

	basicConstraints=critical,@bs_section

	[bs_section]

	CA=true
	pathlen=1

	Both forms are equivalent.

	The syntax of raw extensions is governed by the extension code: it can
	for example contain data in multiple sections. The correct syntax to
	use is defined by the extension code itself: check out the certificate
	policies extension for an example.

	If an extension type is unsupported then the I<arbitrary> extension syntax
	must be used, see the L<ARBITRARY EXTENSIONS\|/"ARBITRARY EXTENSIONS"> section for more details.

	=head1 STANDARD EXTENSIONS

	The following sections describe each supported extension in detail.

	=head2 Basic Constraints.

	This is a multi valued extension which indicates whether a certificate is
	a CA certificate. The first (mandatory) name is B<CA> followed by B<TRUE> or
	B<FALSE>. If B<CA> is B<TRUE> then an optional B<pathlen> name followed by an
	non-negative value can be included.

	For example:

	basicConstraints=CA:TRUE

	basicConstraints=CA:FALSE

	basicConstraints=critical,CA:TRUE, pathlen:0

	A CA certificate B<must> include the basicConstraints value with the CA field
	set to TRUE. An end user certificate must either set CA to FALSE or exclude the
	extension entirely. Some software may require the inclusion of basicConstraints
	with CA set to FALSE for end entity certificates.

	The pathlen parameter indicates the maximum number of CAs that can appear
	below this one in a chain. So if you have a CA with a pathlen of zero it can
	only be used to sign end user certificates and not further CAs.


	=head2 Key Usage.

	Key usage is a multi valued extension consisting of a list of names of the
	permitted key usages.

	The supported names are: digitalSignature, nonRepudiation, keyEncipherment,
	dataEncipherment, keyAgreement, keyCertSign, cRLSign, encipherOnly
	and decipherOnly.

	Examples:

	keyUsage=digitalSignature, nonRepudiation

	keyUsage=critical, keyCertSign


	=head2 Extended Key Usage.

	This extensions consists of a list of usages indicating purposes for which
	the certificate public key can be used for,

	These can either be object short names or the dotted numerical form of OIDs.
	While any OID can be used only certain values make sense. In particular the
	following PKIX, NS and MS values are meaningful:

	Value Meaning
	----- -------
	serverAuth SSL/TLS Web Server Authentication.
	clientAuth SSL/TLS Web Client Authentication.
	codeSigning Code signing.
	emailProtection E-mail Protection (S/MIME).
	timeStamping Trusted Timestamping
	OCSPSigning OCSP Signing
	ipsecIKE ipsec Internet Key Exchange
	msCodeInd Microsoft Individual Code Signing (authenticode)
	msCodeCom Microsoft Commercial Code Signing (authenticode)
	msCTLSign Microsoft Trust List Signing
	msEFS Microsoft Encrypted File System

	Examples:

	extendedKeyUsage=critical,codeSigning,1.2.3.4
	extendedKeyUsage=serverAuth,clientAuth


	=head2 Subject Key Identifier.

	This is really a string extension and can take two possible values. Either
	the word B<hash> which will automatically follow the guidelines in RFC3280
	or a hex string giving the extension value to include. The use of the hex
	string is strongly discouraged.

	Example:

	subjectKeyIdentifier=hash


	=head2 Authority Key Identifier.

	The authority key identifier extension permits two options. keyid and issuer:
	both can take the optional value "always".

	If the keyid option is present an attempt is made to copy the subject key
	identifier from the parent certificate. If the value "always" is present
	then an error is returned if the option fails.

	The issuer option copies the issuer and serial number from the issuer
	certificate. This will only be done if the keyid option fails or
	is not included unless the "always" flag will always include the value.

	Example:

	authorityKeyIdentifier=keyid,issuer


	=head2 Subject Alternative Name.

	The subject alternative name extension allows various literal values to be
	included in the configuration file. These include B<email> (an email address)
	B<URI> a uniform resource indicator, B<DNS> (a DNS domain name), B<RID> (a
	registered ID: OBJECT IDENTIFIER), B<IP> (an IP address), B<dirName>
	(a distinguished name) and otherName.

	The email option include a special 'copy' value. This will automatically
	include and email addresses contained in the certificate subject name in
	the extension.

	The IP address used in the B<IP> options can be in either IPv4 or IPv6 format.

	The value of B<dirName> should point to a section containing the distinguished
	name to use as a set of name value pairs. Multi values AVAs can be formed by
	prefacing the name with a B<+> character.

	otherName can include arbitrary data associated with an OID: the value
	should be the OID followed by a semicolon and the content in standard
	L<ASN1_generate_nconf(3)> format.

	Examples:

	subjectAltName=email:copy,email:my@other.address,URI:http://my.url.here/
	subjectAltName=IP:192.168.7.1
	subjectAltName=IP:13::17
	subjectAltName=email:my@other.address,RID:1.2.3.4
	subjectAltName=otherName:1.2.3.4;UTF8:some other identifier

	subjectAltName=dirName:dir_sect

	[dir_sect]
	C=UK
	O=My Organization
	OU=My Unit
	CN=My Name


	=head2 Issuer Alternative Name.

	The issuer alternative name option supports all the literal options of
	subject alternative name. It does B<not> support the email:copy option because
	that would not make sense. It does support an additional issuer:copy option
	that will copy all the subject alternative name values from the issuer
	certificate (if possible).

	Example:

	issuserAltName = issuer:copy


	=head2 Authority Info Access.

	The authority information access extension gives details about how to access
	certain information relating to the CA. Its syntax is accessOID;location
	where I<location> has the same syntax as subject alternative name (except
	that email:copy is not supported). accessOID can be any valid OID but only
	certain values are meaningful, for example OCSP and caIssuers.

	Example:

	authorityInfoAccess = OCSP;URI:http://ocsp.my.host/
	authorityInfoAccess = caIssuers;URI:http://my.ca/ca.html


	=head2 CRL distribution points

	This is a multi-valued extension whose options can be either in name:value pair
	using the same form as subject alternative name or a single value representing
	a section name containing all the distribution point fields.

	For a name:value pair a new DistributionPoint with the fullName field set to
	the given value both the cRLissuer and reasons fields are omitted in this case.

	In the single option case the section indicated contains values for each
	field. In this section:

	If the name is "fullname" the value field should contain the full name
	of the distribution point in the same format as subject alternative name.

	If the name is "relativename" then the value field should contain a section
	name whose contents represent a DN fragment to be placed in this field.

	The name "CRLIssuer" if present should contain a value for this field in
	subject alternative name format.

	If the name is "reasons" the value field should consist of a comma
	separated field containing the reasons. Valid reasons are: "keyCompromise",
	"CACompromise", "affiliationChanged", "superseded", "cessationOfOperation",
	"certificateHold", "privilegeWithdrawn" and "AACompromise".


	Simple examples:

	crlDistributionPoints=URI:http://myhost.com/myca.crl
	crlDistributionPoints=URI:http://my.com/my.crl,URI:http://oth.com/my.crl

	Full distribution point example:

	crlDistributionPoints=crldp1_section

	[crldp1_section]

	fullname=URI:http://myhost.com/myca.crl
	CRLissuer=dirName:issuer_sect
	reasons=keyCompromise, CACompromise

	[issuer_sect]
	C=UK
	O=Organisation
	CN=Some Name

	=head2 Issuing Distribution Point

	This extension should only appear in CRLs. It is a multi valued extension
	whose syntax is similar to the "section" pointed to by the CRL distribution
	points extension with a few differences.

	The names "reasons" and "CRLissuer" are not recognized.

	The name "onlysomereasons" is accepted which sets this field. The value is
	in the same format as the CRL distribution point "reasons" field.

	The names "onlyuser", "onlyCA", "onlyAA" and "indirectCRL" are also accepted
	the values should be a boolean value (TRUE or FALSE) to indicate the value of
	the corresponding field.

	Example:

	issuingDistributionPoint=critical, @idp_section

	[idp_section]

	fullname=URI:http://myhost.com/myca.crl
	indirectCRL=TRUE
	onlysomereasons=keyCompromise, CACompromise

	[issuer_sect]
	C=UK
	O=Organisation
	CN=Some Name


	=head2 Certificate Policies.

	This is a I<raw> extension. All the fields of this extension can be set by
	using the appropriate syntax.

	If you follow the PKIX recommendations and just using one OID then you just
	include the value of that OID. Multiple OIDs can be set separated by commas,
	for example:

	certificatePolicies= 1.2.4.5, 1.1.3.4

	If you wish to include qualifiers then the policy OID and qualifiers need to
	be specified in a separate section: this is done by using the @section syntax
	instead of a literal OID value.

	The section referred to must include the policy OID using the name
	policyIdentifier, cPSuri qualifiers can be included using the syntax:

	CPS.nnn=value

	userNotice qualifiers can be set using the syntax:

	userNotice.nnn=@notice

	The value of the userNotice qualifier is specified in the relevant section.
	This section can include explicitText, organization and noticeNumbers
	options. explicitText and organization are text strings, noticeNumbers is a
	comma separated list of numbers. The organization and noticeNumbers options
	(if included) must BOTH be present. If you use the userNotice option with IE5
	then you need the 'ia5org' option at the top level to modify the encoding:
	otherwise it will not be interpreted properly.

	Example:

	certificatePolicies=ia5org,1.2.3.4,1.5.6.7.8,@polsect

	[polsect]

	policyIdentifier = 1.3.5.8
	CPS.1="http://my.host.name/"
	CPS.2="http://my.your.name/"
	userNotice.1=@notice

	[notice]

	explicitText="Explicit Text Here"
	organization="Organisation Name"
	noticeNumbers=1,2,3,4

	The B<ia5org> option changes the type of the I<organization> field. In RFC2459
	it can only be of type DisplayText. In RFC3280 IA5Strring is also permissible.
	Some software (for example some versions of MSIE) may require ia5org.

	=head2 Policy Constraints

	This is a multi-valued extension which consisting of the names
	B<requireExplicitPolicy> or B<inhibitPolicyMapping> and a non negative integer
	value. At least one component must be present.

	Example:

	policyConstraints = requireExplicitPolicy:3


	=head2 Inhibit Any Policy

	This is a string extension whose value must be a non negative integer.

	Example:

	inhibitAnyPolicy = 2


	=head2 Name Constraints

	The name constraints extension is a multi-valued extension. The name should
	begin with the word B<permitted> or B<excluded> followed by a B<;>. The rest of
	the name and the value follows the syntax of subjectAltName except email:copy
	is not supported and the B<IP> form should consist of an IP addresses and
	subnet mask separated by a B</>.

	Examples:

	nameConstraints=permitted;IP:192.168.0.0/255.255.0.0

	nameConstraints=permitted;email:.somedomain.com

	nameConstraints=excluded;email:.com


	=head2 OCSP No Check

	The OCSP No Check extension is a string extension but its value is ignored.

	Example:

	noCheck = ignored


	=head2 TLS Feature (aka Must Staple)

	This is a multi-valued extension consisting of a list of TLS extension
	identifiers. Each identifier may be a number (0..65535) or a supported name.
	When a TLS client sends a listed extension, the TLS server is expected to
	include that extension in its reply.

	The supported names are: B<status_request> and B<status_request_v2>.

	Example:

	tlsfeature = status_request


	=head1 DEPRECATED EXTENSIONS

	The following extensions are non standard, Netscape specific and largely
	obsolete. Their use in new applications is discouraged.

	=head2 Netscape String extensions.

	Netscape Comment (B<nsComment>) is a string extension containing a comment
	which will be displayed when the certificate is viewed in some browsers.

	Example:

	nsComment = "Some Random Comment"

	Other supported extensions in this category are: B<nsBaseUrl>,
	B<nsRevocationUrl>, B<nsCaRevocationUrl>, B<nsRenewalUrl>, B<nsCaPolicyUrl>
	and B<nsSslServerName>.


	=head2 Netscape Certificate Type

	This is a multi-valued extensions which consists of a list of flags to be
	included. It was used to indicate the purposes for which a certificate could
	be used. The basicConstraints, keyUsage and extended key usage extensions are
	now used instead.

	Acceptable values for nsCertType are: B<client>, B<server>, B<email>,
	B<objsign>, B<reserved>, B<sslCA>, B<emailCA>, B<objCA>.


	=head1 ARBITRARY EXTENSIONS

	If an extension is not supported by the OpenSSL code then it must be encoded
	using the arbitrary extension format. It is also possible to use the arbitrary
	format for supported extensions. Extreme care should be taken to ensure that
	the data is formatted correctly for the given extension type.

	There are two ways to encode arbitrary extensions.

	The first way is to use the word ASN1 followed by the extension content
	using the same syntax as L<ASN1_generate_nconf(3)>.
	For example:

	1.2.3.4=critical,ASN1:UTF8String:Some random data

	1.2.3.4=ASN1:SEQUENCE:seq_sect

	[seq_sect]

	field1 = UTF8:field1
	field2 = UTF8:field2

	It is also possible to use the word DER to include the raw encoded data in any
	extension.

	1.2.3.4=critical,DER:01:02:03:04
	1.2.3.4=DER:01020304

	The value following DER is a hex dump of the DER encoding of the extension
	Any extension can be placed in this form to override the default behaviour.
	For example:

	basicConstraints=critical,DER:00:01:02:03

	=head1 WARNING

	There is no guarantee that a specific implementation will process a given
	extension. It may therefore be sometimes possible to use certificates for
	purposes prohibited by their extensions because a specific application does
	not recognize or honour the values of the relevant extensions.

	The DER and ASN1 options should be used with caution. It is possible to create
	totally invalid extensions if they are not used carefully.


	=head1 NOTES

	If an extension is multi-value and a field value must contain a comma the long
	form must be used otherwise the comma would be misinterpreted as a field
	separator. For example:

	subjectAltName=URI:ldap://somehost.com/CN=foo,OU=bar

	will produce an error but the equivalent form:

	subjectAltName=@subject_alt_section

	[subject_alt_section]
	subjectAltName=URI:ldap://somehost.com/CN=foo,OU=bar

	is valid.

	Due to the behaviour of the OpenSSL B<conf> library the same field name
	can only occur once in a section. This means that:

	subjectAltName=@alt_section

	[alt_section]

	email=steve@here
	email=steve@there

	will only recognize the last value. This can be worked around by using the form:

	[alt_section]

	email.1=steve@here
	email.2=steve@there

	=head1 SEE ALSO

	L<req(1)>, L<ca(1)>, L<x509(1)>,
	L<ASN1_generate_nconf(3)>

	=head1 COPYRIGHT

	Copyright 2004-2016 The OpenSSL Project Authors. All Rights Reserved.

	Licensed under the OpenSSL license (the "License"). You may not use
	this file except in compliance with the License. You can obtain a copy
	in the file LICENSE in the source distribution or at
	L<https://www.openssl.org/source/license.html>.

	=cut