x509v3_config - X509 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.

       Typically the application will contain an option to point to an exten-
       sion 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 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
       policies 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 an
       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

       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, keyEncipher-
       ment, dataEncipherment, keyAgreement, keyCertSign, cRLSign, enci-
       pherOnly and decipherOnly.


        keyUsage=digitalSignature, nonRepudiation

        keyUsage=critical, keyCertSign

       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
        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



       Subject Key Identifier.

       This is really a string extension and can take two possible values.
       Either the word 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.



       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.



       Subject Alternative Name.

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

       The email option include a special 'copy' value. This will automati-
       cally include and 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

       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.


        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
       because that would not make sense. It does support an additional
       issuer:copy option that will copy all the subject alternative name val-
       ues from the issuer certificate (if possible).


        issuserAltName = issuer:copy

       Authority Info Access.

       The authority information access extension gives details about how to
       access certain information relating to the CA. Its syntax is acces-
       sOID;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


        authorityInfoAccess = OCSP;URI:
        authorityInfoAccess = caIssuers;URI:

       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 distribu-
       tion 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 omit-
       ted 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

       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 sep-
       arated field containing the reasons. Valid reasons are: "keyCompro-
       mise", "CACompromise", "affiliationChanged", "superseded", "cessationO-
       fOperation", "certificateHold", "privilegeWithdrawn" and "AACompro-

       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
       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 indi-
       cate the value of the corresponding field.


        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 using 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 pol-
       icyIdentifier, 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 noti-
       ceNumbers 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 inter-
       preted properly.




        policyIdentifier =


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

       The ia5org option changes the type of the 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.

       Policy Constraints

       This is a multi-valued extension which consisting of the names require-
       ExplicitPolicy or inhibitPolicyMapping and a non negative intger value.
       At least one component must be present.


        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 ;. The
       rest of the name and the value follows the syntax of subjectAltName
       except email:copy is not supported and the IP form should consist of an
       IP addresses and subnet mask separated by a /.





       OCSP No Check

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


        noCheck = ignored


       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


        nsComment = "Some Random Comment"

       Other supported extensions in this category are: nsBaseUrl, nsRevoca-
       tionUrl, 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 certifi-
       cate 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
       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(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:



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

       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 equivalent form:



       is valid.

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




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




       The X509v3 extension code was first added to OpenSSL 0.9.2.

       Policy mappings, inhibit any policy and name constraints support was
       added in OpenSSL 0.9.8

       The directoryName and otherName option as well as the ASN1 option for
       arbitrary extensions was added in OpenSSL 0.9.8


       req(1), ca(1), x509(1), ASN1_generate_nconf(3)

1.0.2t                            2019-09-10                  X509V3_CONFIG(5)

Man(1) output converted with man2html