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 * accompanied this code).

 *

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package java.security.cert;

import java.util.Arrays;

import java.security.PublicKey;

import java.security.NoSuchAlgorithmException;

import java.security.NoSuchProviderException;

import java.security.InvalidKeyException;

import java.security.SignatureException;

import sun.security.x509.X509CertImpl;

/**

 * <p>Abstract class for managing a variety of identity certificates.

 * An identity certificate is a binding of a principal to a public key which

 * is vouched for by another principal.  (A principal represents

 * an entity such as an individual user, a group, or a corporation.)

 *<p>

 * This class is an abstraction for certificates that have different

 * formats but important common uses.  For example, different types of

 * certificates, such as X.509 and PGP, share general certificate

 * functionality (like encoding and verifying) and

 * some types of information (like a public key).

 * <p>

 * X.509, PGP, and SDSI certificates can all be implemented by

 * subclassing the Certificate class, even though they contain different

 * sets of information, and they store and retrieve the information in

 * different ways.

 *

 * @see X509Certificate

 * @see CertificateFactory

 *

 * @author Hemma Prafullchandra

 */

public abstract class Certificate implements java.io.Serializable {

    private static final long serialVersionUID = -3585440601605666277L;

    // the certificate type

    private final String type;

    /**

     * Creates a certificate of the specified type.

     *

     * @param type the standard name of the certificate type.

     * See the CertificateFactory section in the <a href=

     * "{@docRoot}/../technotes/guides/security/StandardNames.html#CertificateFactory">

     * Java Cryptography Architecture Standard Algorithm Name Documentation</a>

     * for information about standard certificate types.

     */

    protected Certificate(String type) {

        this.type = type;

    }

    /**

     * Returns the type of this certificate.

     *

     * @return the type of this certificate.

     */

    public final String getType() {

        return this.type;

    }

    /**

     * Compares this certificate for equality with the specified

     * object. If the <code>other</code> object is an

     * <code>instanceof</code> <code>Certificate</code>, then

     * its encoded form is retrieved and compared with the

     * encoded form of this certificate.

     *

     * @param other the object to test for equality with this certificate.

     * @return true iff the encoded forms of the two certificates

     * match, false otherwise.

     */

    public boolean equals(Object other) {

        if (this == other) {

            return true;

        }

        if (!(other instanceof Certificate)) {

            return false;

        }

        try {

            byte[] thisCert = X509CertImpl.getEncodedInternal(this);

            byte[] otherCert = X509CertImpl.getEncodedInternal((Certificate)other);

            return Arrays.equals(thisCert, otherCert);

        } catch (CertificateException e) {

            return false;

        }

    }

    /**

     * Returns a hashcode value for this certificate from its

     * encoded form.

     *

     * @return the hashcode value.

     */

    public int hashCode() {

        int retval = 0;

        try {

            byte[] certData = X509CertImpl.getEncodedInternal(this);

            for (int i = 1; i < certData.length; i++) {

                 retval += certData[i] * i;

            }

            return retval;

        } catch (CertificateException e) {

            return retval;

        }

    }

    /**

     * Returns the encoded form of this certificate. It is

     * assumed that each certificate type would have only a single

     * form of encoding; for example, X.509 certificates would

     * be encoded as ASN.1 DER.

     *

     * @return the encoded form of this certificate

     *

     * @exception CertificateEncodingException if an encoding error occurs.

     */

    public abstract byte[] getEncoded()

        throws CertificateEncodingException;

    /**

     * Verifies that this certificate was signed using the

     * private key that corresponds to the specified public key.

     *

     * @param key the PublicKey used to carry out the verification.

     *

     * @exception NoSuchAlgorithmException on unsupported signature

     * algorithms.

     * @exception InvalidKeyException on incorrect key.

     * @exception NoSuchProviderException if there's no default provider.

     * @exception SignatureException on signature errors.

     * @exception CertificateException on encoding errors.

     */

    public abstract void verify(PublicKey key)

        throws CertificateException, NoSuchAlgorithmException,

        InvalidKeyException, NoSuchProviderException,

        SignatureException;

    /**

     * Verifies that this certificate was signed using the

     * private key that corresponds to the specified public key.

     * This method uses the signature verification engine

     * supplied by the specified provider.

     *

     * @param key the PublicKey used to carry out the verification.

     * @param sigProvider the name of the signature provider.

     *

     * @exception NoSuchAlgorithmException on unsupported signature

     * algorithms.

     * @exception InvalidKeyException on incorrect key.

     * @exception NoSuchProviderException on incorrect provider.

     * @exception SignatureException on signature errors.

     * @exception CertificateException on encoding errors.

     */

    public abstract void verify(PublicKey key, String sigProvider)

        throws CertificateException, NoSuchAlgorithmException,

        InvalidKeyException, NoSuchProviderException,

        SignatureException;

    /**

     * Returns a string representation of this certificate.

     *

     * @return a string representation of this certificate.

     */

    public abstract String toString();

    /**

     * Gets the public key from this certificate.

     *

     * @return the public key.

     */

    public abstract PublicKey getPublicKey();

    /**

     * Alternate Certificate class for serialization.

     * @since 1.3

     */

    protected static class CertificateRep implements java.io.Serializable {

        private static final long serialVersionUID = -8563758940495660020L;

        private String type;

        private byte[] data;

        /**

         * Construct the alternate Certificate class with the Certificate

         * type and Certificate encoding bytes.

         *

         * <p>

         *

         * @param type the standard name of the Certificate type. <p>

         *

         * @param data the Certificate data.

         */

        protected CertificateRep(String type, byte[] data) {

            this.type = type;

            this.data = data;

        }

        /**

         * Resolve the Certificate Object.

         *

         * <p>

         *

         * @return the resolved Certificate Object

         *

         * @throws java.io.ObjectStreamException if the Certificate

         *      could not be resolved

         */

        protected Object readResolve() throws java.io.ObjectStreamException {

            try {

                CertificateFactory cf = CertificateFactory.getInstance(type);

                return cf.generateCertificate

                        (new java.io.ByteArrayInputStream(data));

            } catch (CertificateException e) {

                throw new java.io.NotSerializableException

                                ("java.security.cert.Certificate: " +

                                type +

                                ": " +

                                e.getMessage());

            }

        }

    }

    /**

     * Replace the Certificate to be serialized.

     *

     * @return the alternate Certificate object to be serialized

     *

     * @throws java.io.ObjectStreamException if a new object representing

     * this Certificate could not be created

     * @since 1.3

     */

    protected Object writeReplace() throws java.io.ObjectStreamException {

        try {

            return new CertificateRep(type, getEncoded());

        } catch (CertificateException e) {

            throw new java.io.NotSerializableException

                                ("java.security.cert.Certificate: " +

                                type +

                                ": " +

                                e.getMessage());

        }

    }

}