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package sun.security.x509;

import java.io.IOException;
import java.io.OutputStream;
import java.util.Arrays;
import sun.security.util.*;


Represent a X509 Extension Attribute.

Extensions are additional attributes which can be inserted in a X509
v3 certificate. For example a "Driving License Certificate" could have
the driving license number as a extension.

Extensions are represented as a sequence of the extension identifier
(Object Identifier), a boolean flag stating whether the extension is to
be treated as being critical and the extension value itself (this is again
a DER encoding of the extension value).

ASN.1 definition of Extension:
Extension ::= SEQUENCE {
     ExtensionId     OBJECT IDENTIFIER,
     critical        BOOLEAN DEFAULT FALSE,
     extensionValue  OCTET STRING
}


All subclasses need to implement a constructor of the form


    <subclass> (Boolean, Object)


where the Object is typically an array of DER encoded bytes.

Author:Amit Kapoor, Hemma Prafullchandra
/**
 * Represent a X509 Extension Attribute.
 *
 * <p>Extensions are additional attributes which can be inserted in a X509
 * v3 certificate. For example a "Driving License Certificate" could have
 * the driving license number as a extension.
 *
 * <p>Extensions are represented as a sequence of the extension identifier
 * (Object Identifier), a boolean flag stating whether the extension is to
 * be treated as being critical and the extension value itself (this is again
 * a DER encoding of the extension value).
 * <pre>
 * ASN.1 definition of Extension:
 * Extension ::= SEQUENCE {
 *      ExtensionId     OBJECT IDENTIFIER,
 *      critical        BOOLEAN DEFAULT FALSE,
 *      extensionValue  OCTET STRING
 * }
 * </pre>
 * All subclasses need to implement a constructor of the form
 * <pre>{@code
 *     <subclass> (Boolean, Object)
 * }</pre>
 * where the Object is typically an array of DER encoded bytes.
 *
 * @author Amit Kapoor
 * @author Hemma Prafullchandra
 */
public class Extension implements java.security.cert.Extension {

    protected ObjectIdentifier  extensionId = null;
    protected boolean           critical = false;
    protected byte[]            extensionValue = null;

    
Default constructor.  Used only by sub-classes.

/**
     * Default constructor.  Used only by sub-classes.
     */
    public Extension() { }

    
Constructs an extension from a DER encoded array of bytes.

/**
     * Constructs an extension from a DER encoded array of bytes.
     */
    public Extension(DerValue derVal) throws IOException {

        DerInputStream in = derVal.toDerInputStream();

        // Object identifier
        extensionId = in.getOID();

        // If the criticality flag was false, it will not have been encoded.
        DerValue val = in.getDerValue();
        if (val.tag == DerValue.tag_Boolean) {
            critical = val.getBoolean();

            // Extension value (DER encoded)
            val = in.getDerValue();
            extensionValue = val.getOctetString();
        } else {
            critical = false;
            extensionValue = val.getOctetString();
        }
    }

    
Constructs an Extension from individual components of ObjectIdentifier,
criticality and the DER encoded OctetString.

Params:
  • extensionId – the ObjectIdentifier of the extension
  • critical – the boolean indicating if the extension is critical
  • extensionValue – the DER encoded octet string of the value.
/**
     * Constructs an Extension from individual components of ObjectIdentifier,
     * criticality and the DER encoded OctetString.
     *
     * @param extensionId the ObjectIdentifier of the extension
     * @param critical the boolean indicating if the extension is critical
     * @param extensionValue the DER encoded octet string of the value.
     */
    public Extension(ObjectIdentifier extensionId, boolean critical,
                     byte[] extensionValue) throws IOException {
        this.extensionId = extensionId;
        this.critical = critical;
        // passed in a DER encoded octet string, strip off the tag
        // and length
        DerValue inDerVal = new DerValue(extensionValue);
        this.extensionValue = inDerVal.getOctetString();
    }

    
Constructs an Extension from another extension. To be used for
creating decoded subclasses.

Params:
  • ext – the extension to create from.
/**
     * Constructs an Extension from another extension. To be used for
     * creating decoded subclasses.
     *
     * @param ext the extension to create from.
     */
    public Extension(Extension ext) {
        this.extensionId = ext.extensionId;
        this.critical = ext.critical;
        this.extensionValue = ext.extensionValue;
    }

    
Constructs an Extension from individual components of ObjectIdentifier,
criticality and the raw encoded extension value.

Params:
  • extensionId – the ObjectIdentifier of the extension
  • critical – the boolean indicating if the extension is critical
  • rawExtensionValue – the raw DER-encoded extension value (this
is not the encoded OctetString).
/**
     * Constructs an Extension from individual components of ObjectIdentifier,
     * criticality and the raw encoded extension value.
     *
     * @param extensionId the ObjectIdentifier of the extension
     * @param critical the boolean indicating if the extension is critical
     * @param rawExtensionValue the raw DER-encoded extension value (this
     * is not the encoded OctetString).
     */
    public static Extension newExtension(ObjectIdentifier extensionId,
        boolean critical, byte[] rawExtensionValue) throws IOException {
        Extension ext = new Extension();
        ext.extensionId = extensionId;
        ext.critical = critical;
        ext.extensionValue = rawExtensionValue;
        return ext;
    }

    public void encode(OutputStream out) throws IOException {
        if (out == null) {
            throw new NullPointerException();
        }

        DerOutputStream dos1 = new DerOutputStream();
        DerOutputStream dos2 = new DerOutputStream();

        dos1.putOID(extensionId);
        if (critical) {
            dos1.putBoolean(critical);
        }
        dos1.putOctetString(extensionValue);

        dos2.write(DerValue.tag_Sequence, dos1);
        out.write(dos2.toByteArray());
    }

    
Write the extension to the DerOutputStream.

Params:
  • out – the DerOutputStream to write the extension to.
Throws:
/**
     * Write the extension to the DerOutputStream.
     *
     * @param out the DerOutputStream to write the extension to.
     * @exception IOException on encoding errors
     */
    public void encode(DerOutputStream out) throws IOException {

        if (extensionId == null)
            throw new IOException("Null OID to encode for the extension!");
        if (extensionValue == null)
            throw new IOException("No value to encode for the extension!");

        DerOutputStream dos = new DerOutputStream();

        dos.putOID(extensionId);
        if (critical)
            dos.putBoolean(critical);
        dos.putOctetString(extensionValue);

        out.write(DerValue.tag_Sequence, dos);
    }

    
Returns true if extension is critical.

/**
     * Returns true if extension is critical.
     */
    public boolean isCritical() {
        return critical;
    }

    
Returns the ObjectIdentifier of the extension.

/**
     * Returns the ObjectIdentifier of the extension.
     */
    public ObjectIdentifier getExtensionId() {
        return extensionId;
    }

    public byte[] getValue() {
        return extensionValue.clone();
    }

    
Returns the extension value as an byte array for further processing.
Note, this is the raw DER value of the extension, not the DER
encoded octet string which is in the certificate.
This method does not return a clone; it is the responsibility of the
caller to clone the array if necessary.

/**
     * Returns the extension value as an byte array for further processing.
     * Note, this is the raw DER value of the extension, not the DER
     * encoded octet string which is in the certificate.
     * This method does not return a clone; it is the responsibility of the
     * caller to clone the array if necessary.
     */
    public byte[] getExtensionValue() {
        return extensionValue;
    }

    public String getId() {
        return extensionId.toString();
    }

    
Returns the Extension in user readable form.

/**
     * Returns the Extension in user readable form.
     */
    public String toString() {
        return "ObjectId: " + extensionId +
                " Criticality=" + critical + '\n';
    }

    // Value to mix up the hash
    private static final int hashMagic = 31;

    
Returns a hashcode value for this Extension.

Returns:the hashcode value.
/**
     * Returns a hashcode value for this Extension.
     *
     * @return the hashcode value.
     */
    public int hashCode() {
        int h = 0;
        if (extensionValue != null) {
            byte[] val = extensionValue;
            int len = val.length;
            while (len > 0)
                h += len * val[--len];
        }
        h = h * hashMagic + extensionId.hashCode();
        h = h * hashMagic + (critical?1231:1237);
        return h;
    }

    
Compares this Extension for equality with the specified
object. If the other object is an
instanceof Extension, then
its encoded form is retrieved and compared with the
encoded form of this Extension.

Params:
  • other – the object to test for equality with this Extension.
Returns:true iff the other object is of type Extension, and the
criticality flag, object identifier and encoded extension value of
the two Extensions match, false otherwise.
/**
     * Compares this Extension for equality with the specified
     * object. If the <code>other</code> object is an
     * <code>instanceof</code> <code>Extension</code>, then
     * its encoded form is retrieved and compared with the
     * encoded form of this Extension.
     *
     * @param other the object to test for equality with this Extension.
     * @return true iff the other object is of type Extension, and the
     * criticality flag, object identifier and encoded extension value of
     * the two Extensions match, false otherwise.
     */
    public boolean equals(Object other) {
        if (this == other)
            return true;
        if (!(other instanceof Extension))
            return false;
        Extension otherExt = (Extension) other;
        if (critical != otherExt.critical)
            return false;
        if (!extensionId.equals(otherExt.extensionId))
            return false;
        return Arrays.equals(extensionValue, otherExt.extensionValue);
    }
}