Provided by: openssl_0.9.8g-4ubuntu3_i386 bug

NAME

       x509v3_config - X509 V3 certificate extension configuration format

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 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:

        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 arbitrary extension syntax
       must be used, see the ARBITRART EXTENSIONS section for more details.

STANDARD EXTENSIONS

       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=CA:TRUE

        basicConstraints=CA:FALSE

        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
       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.

       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

       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

       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.

       Example:

        subjectKeyIdentifier=hash

       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

       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
       automatically 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
       format.

       The value of 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 + 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=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

       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
       values from the issuer certificate (if possible).

       Example:

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

       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

       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:

        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 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
       requireExplicitPolicy or inhibitPolicyMapping and a non negative intger
       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.

       Example:

        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 /.

       Examples:

        nameConstraints=permitted;IP:192.168.0.0/255.255.0.0

        nameConstraints=permitted;email:.somedomain.com

        nameConstraints=excluded;email:.com

DEPRECATED EXTENSIONS

       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.

       Example:

        nsComment = "Some Random Comment"

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

       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.

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

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.

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 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

HISTORY

       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

SEE ALSO

       req(1), ca(1), x509(1)