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package java.security.cert;
import java.security.KeyStore;
import java.security.KeyStoreException;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidParameterException;
import java.util.Set;
/**
* Parameters used as input for the PKIX <code>CertPathBuilder</code>
* algorithm.
* <p>
* A PKIX <code>CertPathBuilder</code> uses these parameters to {@link
* CertPathBuilder#build build} a <code>CertPath</code> which has been
* validated according to the PKIX certification path validation algorithm.
*
* <p>To instantiate a <code>PKIXBuilderParameters</code> object, an
* application must specify one or more <i>most-trusted CAs</i> as defined by
* the PKIX certification path validation algorithm. The most-trusted CA
* can be specified using one of two constructors. An application
* can call {@link #PKIXBuilderParameters(Set, CertSelector)
* PKIXBuilderParameters(Set, CertSelector)}, specifying a
* <code>Set</code> of <code>TrustAnchor</code> objects, each of which
* identifies a most-trusted CA. Alternatively, an application can call
* {@link #PKIXBuilderParameters(KeyStore, CertSelector)
* PKIXBuilderParameters(KeyStore, CertSelector)}, specifying a
* <code>KeyStore</code> instance containing trusted certificate entries, each
* of which will be considered as a most-trusted CA.
*
* <p>In addition, an application must specify constraints on the target
* certificate that the <code>CertPathBuilder</code> will attempt
* to build a path to. The constraints are specified as a
* <code>CertSelector</code> object. These constraints should provide the
* <code>CertPathBuilder</code> with enough search criteria to find the target
* certificate. Minimal criteria for an <code>X509Certificate</code> usually
* include the subject name and/or one or more subject alternative names.
* If enough criteria is not specified, the <code>CertPathBuilder</code>
* may throw a <code>CertPathBuilderException</code>.
* <p>
* <b>Concurrent Access</b>
* <p>
* Unless otherwise specified, the methods defined in this class are not
* thread-safe. Multiple threads that need to access a single
* object concurrently should synchronize amongst themselves and
* provide the necessary locking. Multiple threads each manipulating
* separate objects need not synchronize.
*
* @see CertPathBuilder
*
* @since 1.4
* @author Sean Mullan
*/
public class PKIXBuilderParameters extends PKIXParameters {
private int maxPathLength = 5;
/**
* Creates an instance of <code>PKIXBuilderParameters</code> with
* the specified <code>Set</code> of most-trusted CAs.
* Each element of the set is a {@link TrustAnchor TrustAnchor}.
*
* <p>Note that the <code>Set</code> is copied to protect against
* subsequent modifications.
*
* @param trustAnchors a <code>Set</code> of <code>TrustAnchor</code>s
* @param targetConstraints a <code>CertSelector</code> specifying the
* constraints on the target certificate
* @throws InvalidAlgorithmParameterException if <code>trustAnchors</code>
* is empty <code>(trustAnchors.isEmpty() == true)</code>
* @throws NullPointerException if <code>trustAnchors</code> is
* <code>null</code>
* @throws ClassCastException if any of the elements of
* <code>trustAnchors</code> are not of type
* <code>java.security.cert.TrustAnchor</code>
*/
public PKIXBuilderParameters(Set<TrustAnchor> trustAnchors, CertSelector
targetConstraints) throws InvalidAlgorithmParameterException
{
super(trustAnchors);
setTargetCertConstraints(targetConstraints);
}
/**
* Creates an instance of <code>PKIXBuilderParameters</code> that
* populates the set of most-trusted CAs from the trusted
* certificate entries contained in the specified <code>KeyStore</code>.
* Only keystore entries that contain trusted <code>X509Certificate</code>s
* are considered; all other certificate types are ignored.
*
* @param keystore a <code>KeyStore</code> from which the set of
* most-trusted CAs will be populated
* @param targetConstraints a <code>CertSelector</code> specifying the
* constraints on the target certificate
* @throws KeyStoreException if <code>keystore</code> has not been
* initialized
* @throws InvalidAlgorithmParameterException if <code>keystore</code> does
* not contain at least one trusted certificate entry
* @throws NullPointerException if <code>keystore</code> is
* <code>null</code>
*/
public PKIXBuilderParameters(KeyStore keystore,
CertSelector targetConstraints)
throws KeyStoreException, InvalidAlgorithmParameterException
{
super(keystore);
setTargetCertConstraints(targetConstraints);
}
/**
* Sets the value of the maximum number of non-self-issued intermediate
* certificates that may exist in a certification path. A certificate
* is self-issued if the DNs that appear in the subject and issuer
* fields are identical and are not empty. Note that the last certificate
* in a certification path is not an intermediate certificate, and is not
* included in this limit. Usually the last certificate is an end entity
* certificate, but it can be a CA certificate. A PKIX
* <code>CertPathBuilder</code> instance must not build
* paths longer than the length specified.
*
* <p> A value of 0 implies that the path can only contain
* a single certificate. A value of -1 implies that the
* path length is unconstrained (i.e. there is no maximum).
* The default maximum path length, if not specified, is 5.
* Setting a value less than -1 will cause an exception to be thrown.
*
* <p> If any of the CA certificates contain the
* <code>BasicConstraintsExtension</code>, the value of the
* <code>pathLenConstraint</code> field of the extension overrides
* the maximum path length parameter whenever the result is a
* certification path of smaller length.
*
* @param maxPathLength the maximum number of non-self-issued intermediate
* certificates that may exist in a certification path
* @throws InvalidParameterException if <code>maxPathLength</code> is set
* to a value less than -1
*
* @see #getMaxPathLength
*/
public void setMaxPathLength(int maxPathLength) {
if (maxPathLength < -1) {
throw new InvalidParameterException("the maximum path "
+ "length parameter can not be less than -1");
}
this.maxPathLength = maxPathLength;
}
/**
* Returns the value of the maximum number of intermediate non-self-issued
* certificates that may exist in a certification path. See
* the {@link #setMaxPathLength} method for more details.
*
* @return the maximum number of non-self-issued intermediate certificates
* that may exist in a certification path, or -1 if there is no limit
*
* @see #setMaxPathLength
*/
public int getMaxPathLength() {
return maxPathLength;
}
/**
* Returns a formatted string describing the parameters.
*
* @return a formatted string describing the parameters
*/
public String toString() {
StringBuffer sb = new StringBuffer();
sb.append("[\n");
sb.append(super.toString());
sb.append(" Maximum Path Length: " + maxPathLength + "\n");
sb.append("]\n");
return sb.toString();
}
}