--- /dev/null
+=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 ARBITRARY EXTENSION 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 supporte 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 of 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
+ msCodeInd Microsoft Individual Code Signing (authenticode)
+ msCodeCom Microsoft Commercial Code Signing (authenticode)
+ msCTLSign Microsoft Trust List Signing
+ msSGC Microsoft Server Gated Crypto
+ msEFS Microsoft Encrypted File System
+ nsSGC Netscape Server Gated Crypto
+
+Examples:
+
+ extendedKeyUsage=critical,codeSigning,1.2.3.4
+ extendedKeyUsage=nsSGC,msSGC
+
+
+=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. Normally this will only be done if the keyid option fails or
+is not included: the "always" flag will always include the value.
+
+
+=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 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
+preceeding 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
+ASN1_generate_nconf() format.
+
+Examples:
+
+ subjectAltName=email:copy,email:my@other.address,URI:http://my.url.here/
+ 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 that supports all the literal options of
+subject alternative name. Of the few software packages that currently interpret
+this extension most only interpret the URI option.
+
+Currently each option will set a new DistributionPoint with the fullName
+field set to the given value.
+
+Other fields like cRLissuer and reasons cannot currently be set or displayed:
+at this time no examples were available that used these fields.
+
+Examples:
+
+ crlDistributionPoints=URI:http://myhost.com/myca.crl
+ crlDistributionPoints=URI:http://my.com/my.crl,URI:http://oth.com/my.crl
+
+=head2 Certificate Policies.
+
+This is a B<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.
+
+
+=head1 DEPRECATED EXTENSIONS
+
+The following extensions are considered 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 ASN1_generate_nconf(). 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
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