iaik.x509.extensions
Class NameConstraints

java.lang.Object
  |
  +--iaik.x509.V3Extension
        |
        +--iaik.x509.extensions.NameConstraints

public class NameConstraints

extends V3Extension

This class implements the NameConstraints extension.

The NameConstraints extension is a critical standard X509v3 extension for being used in CA certificates.

Each extension is associated with a specific certificateExtension object identifier, derived from:

 certificateExtension  OBJECT IDENTIFIER ::=
                            {joint-iso-ccitt(2) ds(5) 29}
 id-ce                 OBJECT IDENTIFIER ::=  certificateExtension
 

The object identifier for the NameConstraints extension is defined as:

id-ce-nameConstraints OBJECT IDENTIFIER ::= { id-ce 30 }

which corresponds to the OID string "2.5.29.30".

The X.509 Certificate and CRL profile presented in RFC 2459 specifies the Name Constraints extension for indicating a name space within which all subject names in subsequent certificates in a certification path must be located. Restrictions may apply to the subject distinguished name or subject alternative names. Restrictions are defined in terms of permitted or excluded name subtrees. Any name matching a restriction in the excludedSubtrees field is invalid regardless of information appearing in the permittedSubtrees:

 NameConstraints ::= SEQUENCE {
   permittedSubtrees       [0]     GeneralSubtrees OPTIONAL,
   excludedSubtrees        [1]     GeneralSubtrees OPTIONAL }
 

 GeneralSubtrees ::= SEQUENCE SIZE (1..MAX) OF GeneralSubtree
 GeneralSubtree ::= SEQUENCE {
   base                    GeneralName,
   minimum         [0]     BaseDistance DEFAULT 0,
   maximum         [1]     BaseDistance OPTIONAL }
 

 BaseDistance ::= INTEGER (0..MAX)
 

Within this profile, the minimum and maximum fields are not used with any name forms, thus minimum is always zero, and maximum is always absent.

Restrictions for the rfc822, dNSName, and uri name forms are all expressed in terms of strings with wild card matching. An "*" is the wildcard character. For uris and rfc822 names, the restriction applies to the host part of the name. Examples would be foo.bar.com; www*.bar.com; *.xyz.com.

More information can be found in RFC 2459, section 4.2.1.11 "Name Constraints".

For adding a NameConstraints extension object to a X509Certificate, use the addExtension method of the iaik.x509.X509Certificate class. The subtree information supplied when creating a NameConstraints object has to be an array of type iaik.asn1.structures.GeneralSubtree, e.g.:

 NameConstraints nameConstraints = new NameConstraints();
 GeneralSubtree generalSubtree = new GeneralSubtree(new GeneralName(GeneralName.rfc822Name, "*.tu-graz.ac.at"));
 generalSubtree.setMinimum(1);
 generalSubtree.setMaximum(3);
 nameConstraints.setPermittedSubtrees(new GeneralSubtree[] {generalSubtree});
 X509Certificate cert = new X509Certificate();
  ...
 cert.addExtension(nameConstraints);
 

Since the NameConstraints extension is a critical extension, critical has to be set to true before adding the NameConstraints extension to a certificate:

 nameConstraints.setCritical(true);
 

Version:

File Revision 21

See Also:

GeneralSubtree, GeneralName, V3Extension, X509Extensions, X509Certificate

Field Summary

static ObjectID

oid The object identifier of this NameConstraints extension.

Fields inherited from class iaik.x509.V3Extension

critical

Constructor Summary

NameConstraints()
Default costructor.

Method Summary

GeneralSubtree[]	getExcludedSubtrees() Returns the excluded subtrees.
ObjectID	getObjectID() Returns the object ID of this NameConstraints extension
GeneralSubtree[]	getPermittedSubtrees() Returns the permitted subtrees.
int	hashCode() Returns a hashcode for this identity.
void	init(ASN1Object obj) Inits this NameConstraints implementation with an ASN1object representing the value of this extension.
void	setExcludedSubtrees(GeneralSubtree[] excludedSubtrees) Sets the excluded subtrees.
void	setPermittedSubtrees(GeneralSubtree[] permittedSubtrees) Sets the permitted subtrees.
ASN1Object	toASN1Object() Returns an ASN1Object representing the value of this NameConstraints extension object.
String	toString() Returns a string that represents the contents of NameConstraints extension.

Methods inherited from class iaik.x509.V3Extension

getName, isCritical, setCritical

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

oid

public static final ObjectID oid

The object identifier of this NameConstraints extension. The corresponding OID string is "2.5.29.30".

Constructor Detail

NameConstraints

public NameConstraints()

Default costructor.

Creates an empty NameConstraints object. Use setExcludedSubtrees or/and setPermittedSubtrees for adding any restricting information to this extension.

Do not forget to specify this extension as critical before adding it to a certificate:

 NameConstraints nameConstraints = new NameConstraints();
 GeneralSubtree generalSubtree = new GeneralSubtree(new GeneralName(GeneralName.rfc822Name, "*.tu-graz.ac.at"));
 generalSubtree.setMinimum(1);
 generalSubtree.setMaximum(3);
 nameConstraints.setPermittedSubtrees(new GeneralSubtree[] {generalSubtree});
 nameConstraints.setCritical(true);
 X509Certificate cert = new X509Certificate();
  ...
 cert.addExtension(nameConstraints);
 

See Also:

GeneralSubtree, V3Extension.setCritical(boolean)

Method Detail

toASN1Object

public ASN1Object toASN1Object()
                        throws X509ExtensionException

Returns an ASN1Object representing the value of this NameConstraints extension object.

The returned ASN1Object is an ASN.1 Sequence representing any included permitted or excluded subtree information:

 NameConstraints ::= SEQUENCE {
   permittedSubtrees       [0]     GeneralSubtrees OPTIONAL,
   excludedSubtrees        [1]     GeneralSubtrees OPTIONAL }
 

Overrides:

toASN1Object in class V3Extension

Returns:

the value of this NameConstraints as ASN1Object

init

public void init(ASN1Object obj)
          throws X509ExtensionException

Inits this NameConstraints implementation with an ASN1object representing the value of this extension.

The given ASN1Object represents a sequence of permitted/excluded subtree informations.

The given ASN1Object is the one created by toASN1Object().

This method is used by the X509Extensions class when parsing the ASN.1 representation of a certificate for properly initializing an included NameConstraints extension. This method initializes the extension only with its value, but not with its critical specification. For that reason, this method shall not be explicitly called by an application.

Overrides:

init in class V3Extension

Parameters:

obj - the NameConstraints as ASN1Object

Throws:

X509ExtensionException - if the extension could not be parsed

hashCode

public int hashCode()

Returns a hashcode for this identity.

Overrides:

hashCode in class V3Extension

Returns:

a hash code for this identity

getObjectID

public ObjectID getObjectID()

Returns the object ID of this NameConstraints extension

Overrides:

getObjectID in class V3Extension

Returns:

the object ID

setPermittedSubtrees

public void setPermittedSubtrees(GeneralSubtree[] permittedSubtrees)

Sets the permitted subtrees.

Parameters:

permittedSubtrees - the permitted subtrees as array of GeneralSubtree

See Also:

GeneralSubtree

setExcludedSubtrees

public void setExcludedSubtrees(GeneralSubtree[] excludedSubtrees)

Sets the excluded subtrees.

Parameters:

excludedSubtrees - the excluded subtrees as array of GeneralSubtree

See Also:

GeneralSubtree

getPermittedSubtrees

public GeneralSubtree[] getPermittedSubtrees()

Returns the permitted subtrees.

Returns:

the permitted subtrees as array of GeneralSubtree

See Also:

GeneralSubtree

getExcludedSubtrees

public GeneralSubtree[] getExcludedSubtrees()

Returns the excluded subtrees.

Returns:

the excluded subtrees as array of GeneralSubtree

See Also:

GeneralSubtree

toString

public String toString()

Returns a string that represents the contents of NameConstraints extension.

Overrides:

toString in class Object

Returns:

the string representation