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X509V3.CNF(5)		  FreeBSD File Formats Manual		 X509V3.CNF(5)

     x509v3.cnf	-- X.509 V3 certificate	extension configuration	format

     Several of	the OpenSSL utilities can add extensions to a certificate or
     certificate request based on the contents of a configuration file.	 The
     file format is based on the openssl.cnf(5)	format.

     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	critical is present, then the extension	will be	critical.

     The format	of extension_options depends on	the value of extension_name.

     There are four main types of extension: string extensions,	multi-valued
     extensions, raw extensions, and 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:


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



     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	poli-
     cies extension for	an example.

     If	an extension type is unsupported, then the arbitrary extension syntax
     must be used; see the ARBITRARY EXTENSIONS	section	for more details.

     The following sections describe each supported extension in detail.

   Basic constraints
     This is a multi-valued extension which indicates whether a	certificate is
     a CA certificate.	The first (mandatory) name is CA followed by TRUE or
     FALSE.  If	CA is TRUE, then an optional pathlen name followed by a	non-
     negative value can	be included.  For example:

	   basicConstraints=critical,CA:TRUE, pathlen:0

     A CA certificate 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 inclu-
     sion of basicConstraints with CA set to FALSE for end entity certifi-

     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.

   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

   Extended key	usage
     This extension consists of	a list of purposes for which the certificate
     public key	can be used.

     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		TLS server authentication
     clientAuth		TLS 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



   Subject key identifier
     This is really a string extension and can take two	possible values.  Ei-
     ther the word hash	which will automatically follow	the guidelines in RFC
     3280 or a hex string giving the extension value to	include.  The use of
     the hex string is strongly	discouraged.  Example:


   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:


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

     The email option can include a special copy value.	 This will automati-
     cally include any email addresses contained in the	certificate subject
     name in the extension.

     The IP address used in the	IP options can be in either IPv4 or IPv6 for-

     The value of dirName should point to a section containing the distin-
     guished name to use as a set of name value	pairs.	Multi values AVAs can
     be	formed by prefacing the	name with a `+'	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
     ASN1_generate_nconf(3) format.  Examples:

       subjectAltName=otherName:;UTF8:some other	identifier


       O=My Organization
       OU=My Unit
       CN=My Name

   Issuer alternative name
     The issuer	alternative name option	supports all the literal options of
     subject alternative name.	It does	not support the	email:copy option be-
     cause 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:

	   issuerAltName = issuer:copy

   Authority info access
     The authority information access extension	gives details about how	to ac-
     cess certain information relating to the CA.  Its syntax is accessOID;
     location where 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:
	   authorityInfoAccess = caIssuers;URI:

   CRL distribution points
     This is a multi-valued extension whose options can	be either in
     name:value	pair form 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	sec-
     tion name whose contents represent	a DN fragment to be placed in this

     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 sepa-
     rated field containing the	reasons.  Valid	reasons	are: keyCompromise,
     CACompromise, affiliationChanged, superseded, cessationOfOperation,
     certificateHold, privilegeWithdrawn, and AACompromise.

     Simple examples:


     Full distribution point example:


	   reasons=keyCompromise, CACompromise

	   CN=Some Name

   Issuing distribution	point
     This extension should only	appear in CRLs.	 It is a multi-valued exten-
     sion whose	syntax is similar to the "section" pointed to by the CRL dis-
     tribution 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 values (TRUE or FALSE) to indicate the
     value of the corresponding	field.	Example:

	   issuingDistributionPoint=critical, @idp_section

	   onlysomereasons=keyCompromise, CACompromise

	   CN=Some Name

   Certificate policies
     This is a raw extension.  All the fields of this extension	can be set by
     using the appropriate syntax.

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


     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:


     userNotice	qualifiers can be set using the	syntax:


     The value of the userNotice qualifier is specified	in the relevant	sec-
     tion.  This section can include explicitText, organization, and
     noticeNumbers options.  explicitText and organization are text strings,
     and 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	prop-
     erly.  Example:


	   policyIdentifier =

	   explicitText="Explicit Text Here"
	   organization="Organisation Name"

     The ia5org	option changes the type	of the organization field.  In RFC
     2459, it can only be of type DisplayText.	In RFC 3280, IA5String is also
     permissible.  Some	software (for example some versions of MSIE) may re-
     quire ia5org.

   Policy constraints
     This is a multi-valued extension which consists of	the names
     requireExplicitPolicy or inhibitPolicyMapping and a non-negative integer
     value.  At	least one component must be present.  Example:

	   policyConstraints = requireExplicitPolicy:3

   Inhibit any policy
     This is a string extension	whose value must be a non-negative integer.

	   inhibitAnyPolicy = 2

   Name	constraints
     The name constraints extension is a multi-valued extension.  The name
     should begin with the word	permitted or excluded, followed	by a semi-
     colon.  The rest of the name and the value	follows	the syntax of subjec-
     tAltName except email:copy	is not supported and the IP form should	con-
     sist of an	IP addresses and subnet	mask separated by a slash.  Examples:


   OCSP	no check
     The OCSP no check extension is a string extension,	but its	value is ig-
     nored.  Example:

	   noCheck = ignored

   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 in the range	from 0 to
     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: status_request and status_request_v2.  Example:

	   tlsfeature =	status_request

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

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

	   nsComment = Some Random Comment

     Other supported extensions	in this	category are: nsBaseUrl,
     nsRevocationUrl, nsCaRevocationUrl, nsRenewalUrl, nsCaPolicyUrl, and

   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: client, server, email, objsign,
     reserved, sslCA, emailCA, objCA.

     If	an extension is	not supported by the OpenSSL code, then	it must	be en-
     coded 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	exten-
     sion 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 ASN1_generate_nconf(3).  For example:,ASN1:UTF8String:Some random	data

	   field1 = UTF8:field1
	   field2 = UTF8:field2

     It	is also	possible to use	the word DER to	include	the raw	encoded	data
     in	any extension.,DER:01:02:03:04

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


     /etc/ssl/x509v3.cnf  standard configuration file

     openssl(1), ASN1_generate_nconf(3), OPENSSL_config(3), openssl.cnf(5)

     X509v3 extension code was first added to OpenSSL 0.9.2.

     There is no guarantee that	a specific implementation will process a given
     extension.	 It may	therefore sometimes be possible	to use certificates
     for purposes prohibited by	their extensions because a specific applica-
     tion 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.

     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,


     will produce an error, but	the following form is valid:



     Due to the	behaviour of the OpenSSL CONF library, the same	field name can
     only occur	once in	a section.  That means that



     will only use the last value.  This can be	worked around by using the


FreeBSD	13.0			 June 11, 2020			  FreeBSD 13.0


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