jdk/src/share/classes/sun/security/x509/X509CertImpl.java
changeset 2 90ce3da70b43
child 5506 202f599c92aa
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/sun/security/x509/X509CertImpl.java	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,1872 @@
+/*
+ * Copyright 1996-2006 Sun Microsystems, Inc.  All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Sun designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Sun in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+package sun.security.x509;
+
+import java.io.BufferedReader;
+import java.io.BufferedInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.io.OutputStream;
+import java.math.BigInteger;
+import java.security.*;
+import java.security.cert.*;
+import java.security.cert.Certificate;
+import java.util.*;
+
+import javax.security.auth.x500.X500Principal;
+
+import sun.misc.HexDumpEncoder;
+import sun.misc.BASE64Decoder;
+import sun.security.util.*;
+import sun.security.provider.X509Factory;
+
+/**
+ * The X509CertImpl class represents an X.509 certificate. These certificates
+ * are widely used to support authentication and other functionality in
+ * Internet security systems.  Common applications include Privacy Enhanced
+ * Mail (PEM), Transport Layer Security (SSL), code signing for trusted
+ * software distribution, and Secure Electronic Transactions (SET).  There
+ * is a commercial infrastructure ready to manage large scale deployments
+ * of X.509 identity certificates.
+ *
+ * <P>These certificates are managed and vouched for by <em>Certificate
+ * Authorities</em> (CAs).  CAs are services which create certificates by
+ * placing data in the X.509 standard format and then digitally signing
+ * that data.  Such signatures are quite difficult to forge.  CAs act as
+ * trusted third parties, making introductions between agents who have no
+ * direct knowledge of each other.  CA certificates are either signed by
+ * themselves, or by some other CA such as a "root" CA.
+ *
+ * <P>RFC 1422 is very informative, though it does not describe much
+ * of the recent work being done with X.509 certificates.  That includes
+ * a 1996 version (X.509v3) and a variety of enhancements being made to
+ * facilitate an explosion of personal certificates used as "Internet
+ * Drivers' Licences", or with SET for credit card transactions.
+ *
+ * <P>More recent work includes the IETF PKIX Working Group efforts,
+ * especially RFC2459.
+ *
+ * @author Dave Brownell
+ * @author Amit Kapoor
+ * @author Hemma Prafullchandra
+ * @see X509CertInfo
+ */
+public class X509CertImpl extends X509Certificate implements DerEncoder {
+
+    private static final long serialVersionUID = -3457612960190864406L;
+
+    private static final String DOT = ".";
+    /**
+     * Public attribute names.
+     */
+    public static final String NAME = "x509";
+    public static final String INFO = X509CertInfo.NAME;
+    public static final String ALG_ID = "algorithm";
+    public static final String SIGNATURE = "signature";
+    public static final String SIGNED_CERT = "signed_cert";
+
+    /**
+     * The following are defined for ease-of-use. These
+     * are the most frequently retrieved attributes.
+     */
+    // x509.info.subject.dname
+    public static final String SUBJECT_DN = NAME + DOT + INFO + DOT +
+                               X509CertInfo.SUBJECT + DOT +
+                               CertificateSubjectName.DN_NAME;
+    // x509.info.issuer.dname
+    public static final String ISSUER_DN = NAME + DOT + INFO + DOT +
+                               X509CertInfo.ISSUER + DOT +
+                               CertificateIssuerName.DN_NAME;
+    // x509.info.serialNumber.number
+    public static final String SERIAL_ID = NAME + DOT + INFO + DOT +
+                               X509CertInfo.SERIAL_NUMBER + DOT +
+                               CertificateSerialNumber.NUMBER;
+    // x509.info.key.value
+    public static final String PUBLIC_KEY = NAME + DOT + INFO + DOT +
+                               X509CertInfo.KEY + DOT +
+                               CertificateX509Key.KEY;
+
+    // x509.info.version.value
+    public static final String VERSION = NAME + DOT + INFO + DOT +
+                               X509CertInfo.VERSION + DOT +
+                               CertificateVersion.VERSION;
+
+    // x509.algorithm
+    public static final String SIG_ALG = NAME + DOT + ALG_ID;
+
+    // x509.signature
+    public static final String SIG = NAME + DOT + SIGNATURE;
+
+    // when we sign and decode we set this to true
+    // this is our means to make certificates immutable
+    private boolean readOnly = false;
+
+    // Certificate data, and its envelope
+    private byte[]              signedCert = null;
+    protected X509CertInfo      info = null;
+    protected AlgorithmId       algId = null;
+    protected byte[]            signature = null;
+
+    // recognized extension OIDS
+    private static final String KEY_USAGE_OID = "2.5.29.15";
+    private static final String EXTENDED_KEY_USAGE_OID = "2.5.29.37";
+    private static final String BASIC_CONSTRAINT_OID = "2.5.29.19";
+    private static final String SUBJECT_ALT_NAME_OID = "2.5.29.17";
+    private static final String ISSUER_ALT_NAME_OID = "2.5.29.18";
+    private static final String AUTH_INFO_ACCESS_OID = "1.3.6.1.5.5.7.1.1";
+
+    // number of standard key usage bits.
+    private static final int NUM_STANDARD_KEY_USAGE = 9;
+
+    // SubjectAlterntativeNames cache
+    private Collection<List<?>> subjectAlternativeNames;
+
+    // IssuerAlternativeNames cache
+    private Collection<List<?>> issuerAlternativeNames;
+
+    // ExtendedKeyUsage cache
+    private List<String> extKeyUsage;
+
+    // AuthorityInformationAccess cache
+    private Set<AccessDescription> authInfoAccess;
+
+    /**
+     * PublicKey that has previously been used to verify
+     * the signature of this certificate. Null if the certificate has not
+     * yet been verified.
+     */
+    private PublicKey verifiedPublicKey;
+    /**
+     * If verifiedPublicKey is not null, name of the provider used to
+     * successfully verify the signature of this certificate, or the
+     * empty String if no provider was explicitly specified.
+     */
+    private String verifiedProvider;
+    /**
+     * If verifiedPublicKey is not null, result of the verification using
+     * verifiedPublicKey and verifiedProvider. If true, verification was
+     * successful, if false, it failed.
+     */
+    private boolean verificationResult;
+
+    /**
+     * Default constructor.
+     */
+    public X509CertImpl() { }
+
+    /**
+     * Unmarshals a certificate from its encoded form, parsing the
+     * encoded bytes.  This form of constructor is used by agents which
+     * need to examine and use certificate contents.  That is, this is
+     * one of the more commonly used constructors.  Note that the buffer
+     * must include only a certificate, and no "garbage" may be left at
+     * the end.  If you need to ignore data at the end of a certificate,
+     * use another constructor.
+     *
+     * @param certData the encoded bytes, with no trailing padding.
+     * @exception CertificateException on parsing and initialization errors.
+     */
+    public X509CertImpl(byte[] certData) throws CertificateException {
+        try {
+            parse(new DerValue(certData));
+        } catch (IOException e) {
+            signedCert = null;
+            CertificateException ce = new
+                CertificateException("Unable to initialize, " + e);
+            ce.initCause(e);
+            throw ce;
+        }
+    }
+
+    /**
+     * unmarshals an X.509 certificate from an input stream.  If the
+     * certificate is RFC1421 hex-encoded, then it must begin with
+     * the line X509Factory.BEGIN_CERT and end with the line
+     * X509Factory.END_CERT.
+     *
+     * @param in an input stream holding at least one certificate that may
+     *        be either DER-encoded or RFC1421 hex-encoded version of the
+     *        DER-encoded certificate.
+     * @exception CertificateException on parsing and initialization errors.
+     */
+    public X509CertImpl(InputStream in) throws CertificateException {
+
+        DerValue der = null;
+
+        BufferedInputStream inBuffered = new BufferedInputStream(in);
+
+        // First try reading stream as HEX-encoded DER-encoded bytes,
+        // since not mistakable for raw DER
+        try {
+            inBuffered.mark(Integer.MAX_VALUE);
+            der = readRFC1421Cert(inBuffered);
+        } catch (IOException ioe) {
+            try {
+                // Next, try reading stream as raw DER-encoded bytes
+                inBuffered.reset();
+                der = new DerValue(inBuffered);
+            } catch (IOException ioe1) {
+                CertificateException ce = new
+                    CertificateException("Input stream must be " +
+                                         "either DER-encoded bytes " +
+                                         "or RFC1421 hex-encoded " +
+                                         "DER-encoded bytes: " +
+                                         ioe1.getMessage());
+                ce.initCause(ioe1);
+                throw ce;
+            }
+        }
+        try {
+            parse(der);
+        } catch (IOException ioe) {
+            signedCert = null;
+            CertificateException ce = new
+                CertificateException("Unable to parse DER value of " +
+                                     "certificate, " + ioe);
+            ce.initCause(ioe);
+            throw ce;
+        }
+    }
+
+    /**
+     * read input stream as HEX-encoded DER-encoded bytes
+     *
+     * @param in InputStream to read
+     * @returns DerValue corresponding to decoded HEX-encoded bytes
+     * @throws IOException if stream can not be interpreted as RFC1421
+     *                     encoded bytes
+     */
+    private DerValue readRFC1421Cert(InputStream in) throws IOException {
+        DerValue der = null;
+        String line = null;
+        BufferedReader certBufferedReader =
+            new BufferedReader(new InputStreamReader(in, "ASCII"));
+        try {
+            line = certBufferedReader.readLine();
+        } catch (IOException ioe1) {
+            throw new IOException("Unable to read InputStream: " +
+                                  ioe1.getMessage());
+        }
+        if (line.equals(X509Factory.BEGIN_CERT)) {
+            /* stream appears to be hex-encoded bytes */
+            BASE64Decoder         decoder   = new BASE64Decoder();
+            ByteArrayOutputStream decstream = new ByteArrayOutputStream();
+            try {
+                while ((line = certBufferedReader.readLine()) != null) {
+                    if (line.equals(X509Factory.END_CERT)) {
+                        der = new DerValue(decstream.toByteArray());
+                        break;
+                    } else {
+                        decstream.write(decoder.decodeBuffer(line));
+                    }
+                }
+            } catch (IOException ioe2) {
+                throw new IOException("Unable to read InputStream: "
+                                      + ioe2.getMessage());
+            }
+        } else {
+            throw new IOException("InputStream is not RFC1421 hex-encoded " +
+                                  "DER bytes");
+        }
+        return der;
+    }
+
+    /**
+     * Construct an initialized X509 Certificate. The certificate is stored
+     * in raw form and has to be signed to be useful.
+     *
+     * @params info the X509CertificateInfo which the Certificate is to be
+     *              created from.
+     */
+    public X509CertImpl(X509CertInfo certInfo) {
+        this.info = certInfo;
+    }
+
+    /**
+     * Unmarshal a certificate from its encoded form, parsing a DER value.
+     * This form of constructor is used by agents which need to examine
+     * and use certificate contents.
+     *
+     * @param derVal the der value containing the encoded cert.
+     * @exception CertificateException on parsing and initialization errors.
+     */
+    public X509CertImpl(DerValue derVal) throws CertificateException {
+        try {
+            parse(derVal);
+        } catch (IOException e) {
+            signedCert = null;
+            CertificateException ce = new
+                CertificateException("Unable to initialize, " + e);
+            ce.initCause(e);
+            throw ce;
+        }
+    }
+
+    /**
+     * Appends the certificate to an output stream.
+     *
+     * @param out an input stream to which the certificate is appended.
+     * @exception CertificateEncodingException on encoding errors.
+     */
+    public void encode(OutputStream out)
+    throws CertificateEncodingException {
+        if (signedCert == null)
+            throw new CertificateEncodingException(
+                          "Null certificate to encode");
+        try {
+            out.write(signedCert.clone());
+        } catch (IOException e) {
+            throw new CertificateEncodingException(e.toString());
+        }
+    }
+
+    /**
+     * DER encode this object onto an output stream.
+     * Implements the <code>DerEncoder</code> interface.
+     *
+     * @param out the output stream on which to write the DER encoding.
+     *
+     * @exception IOException on encoding error.
+     */
+    public void derEncode(OutputStream out) throws IOException {
+        if (signedCert == null)
+            throw new IOException("Null certificate to encode");
+        out.write(signedCert.clone());
+    }
+
+    /**
+     * 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.
+     *
+     * @exception CertificateEncodingException if an encoding error occurs.
+     */
+    public byte[] getEncoded() throws CertificateEncodingException {
+        return getEncodedInternal().clone();
+    }
+
+    /**
+     * Returned the encoding as an uncloned byte array. Callers must
+     * guarantee that they neither modify it nor expose it to untrusted
+     * code.
+     */
+    public byte[] getEncodedInternal() throws CertificateEncodingException {
+        if (signedCert == null) {
+            throw new CertificateEncodingException(
+                          "Null certificate to encode");
+        }
+        return signedCert;
+    }
+
+    /**
+     * Throws an exception if the certificate was not signed using the
+     * verification key provided.  Successfully verifying a certificate
+     * does <em>not</em> indicate that one should trust the entity which
+     * it represents.
+     *
+     * @param key the public key used for verification.
+     *
+     * @exception InvalidKeyException on incorrect key.
+     * @exception NoSuchAlgorithmException on unsupported signature
+     * algorithms.
+     * @exception NoSuchProviderException if there's no default provider.
+     * @exception SignatureException on signature errors.
+     * @exception CertificateException on encoding errors.
+     */
+    public void verify(PublicKey key)
+    throws CertificateException, NoSuchAlgorithmException,
+        InvalidKeyException, NoSuchProviderException, SignatureException {
+
+        verify(key, "");
+    }
+
+    /**
+     * Throws an exception if the certificate was not signed using the
+     * verification key provided.  Successfully verifying a certificate
+     * does <em>not</em> indicate that one should trust the entity which
+     * it represents.
+     *
+     * @param key the public key used for verification.
+     * @param sigProvider the name of the 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 synchronized void verify(PublicKey key, String sigProvider)
+            throws CertificateException, NoSuchAlgorithmException,
+            InvalidKeyException, NoSuchProviderException, SignatureException {
+        if (sigProvider == null) {
+            sigProvider = "";
+        }
+        if ((verifiedPublicKey != null) && verifiedPublicKey.equals(key)) {
+            // this certificate has already been verified using
+            // this public key. Make sure providers match, too.
+            if (sigProvider.equals(verifiedProvider)) {
+                if (verificationResult) {
+                    return;
+                } else {
+                    throw new SignatureException("Signature does not match.");
+                }
+            }
+        }
+        if (signedCert == null) {
+            throw new CertificateEncodingException("Uninitialized certificate");
+        }
+        // Verify the signature ...
+        Signature sigVerf = null;
+        if (sigProvider.length() == 0) {
+            sigVerf = Signature.getInstance(algId.getName());
+        } else {
+            sigVerf = Signature.getInstance(algId.getName(), sigProvider);
+        }
+        sigVerf.initVerify(key);
+
+        byte[] rawCert = info.getEncodedInfo();
+        sigVerf.update(rawCert, 0, rawCert.length);
+
+        // verify may throw SignatureException for invalid encodings, etc.
+        verificationResult = sigVerf.verify(signature);
+        verifiedPublicKey = key;
+        verifiedProvider = sigProvider;
+
+        if (verificationResult == false) {
+            throw new SignatureException("Signature does not match.");
+        }
+    }
+
+    /**
+     * Creates an X.509 certificate, and signs it using the given key
+     * (associating a signature algorithm and an X.500 name).
+     * This operation is used to implement the certificate generation
+     * functionality of a certificate authority.
+     *
+     * @param key the private key used for signing.
+     * @param algorithm the name of the signature algorithm used.
+     *
+     * @exception InvalidKeyException on incorrect key.
+     * @exception NoSuchAlgorithmException on unsupported signature
+     * algorithms.
+     * @exception NoSuchProviderException if there's no default provider.
+     * @exception SignatureException on signature errors.
+     * @exception CertificateException on encoding errors.
+     */
+    public void sign(PrivateKey key, String algorithm)
+    throws CertificateException, NoSuchAlgorithmException,
+        InvalidKeyException, NoSuchProviderException, SignatureException {
+        sign(key, algorithm, null);
+    }
+
+    /**
+     * Creates an X.509 certificate, and signs it using the given key
+     * (associating a signature algorithm and an X.500 name).
+     * This operation is used to implement the certificate generation
+     * functionality of a certificate authority.
+     *
+     * @param key the private key used for signing.
+     * @param algorithm the name of the signature algorithm used.
+     * @param provider the name of the 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 void sign(PrivateKey key, String algorithm, String provider)
+    throws CertificateException, NoSuchAlgorithmException,
+        InvalidKeyException, NoSuchProviderException, SignatureException {
+        try {
+            if (readOnly)
+                throw new CertificateEncodingException(
+                              "cannot over-write existing certificate");
+            Signature sigEngine = null;
+            if ((provider == null) || (provider.length() == 0))
+                sigEngine = Signature.getInstance(algorithm);
+            else
+                sigEngine = Signature.getInstance(algorithm, provider);
+
+            sigEngine.initSign(key);
+
+                                // in case the name is reset
+            algId = AlgorithmId.get(sigEngine.getAlgorithm());
+
+            DerOutputStream out = new DerOutputStream();
+            DerOutputStream tmp = new DerOutputStream();
+
+            // encode certificate info
+            info.encode(tmp);
+            byte[] rawCert = tmp.toByteArray();
+
+            // encode algorithm identifier
+            algId.encode(tmp);
+
+            // Create and encode the signature itself.
+            sigEngine.update(rawCert, 0, rawCert.length);
+            signature = sigEngine.sign();
+            tmp.putBitString(signature);
+
+            // Wrap the signed data in a SEQUENCE { data, algorithm, sig }
+            out.write(DerValue.tag_Sequence, tmp);
+            signedCert = out.toByteArray();
+            readOnly = true;
+
+        } catch (IOException e) {
+            throw new CertificateEncodingException(e.toString());
+      }
+    }
+
+    /**
+     * Checks that the certificate is currently valid, i.e. the current
+     * time is within the specified validity period.
+     *
+     * @exception CertificateExpiredException if the certificate has expired.
+     * @exception CertificateNotYetValidException if the certificate is not
+     * yet valid.
+     */
+    public void checkValidity()
+    throws CertificateExpiredException, CertificateNotYetValidException {
+        Date date = new Date();
+        checkValidity(date);
+    }
+
+    /**
+     * Checks that the specified date is within the certificate's
+     * validity period, or basically if the certificate would be
+     * valid at the specified date/time.
+     *
+     * @param date the Date to check against to see if this certificate
+     *        is valid at that date/time.
+     *
+     * @exception CertificateExpiredException if the certificate has expired
+     * with respect to the <code>date</code> supplied.
+     * @exception CertificateNotYetValidException if the certificate is not
+     * yet valid with respect to the <code>date</code> supplied.
+     */
+    public void checkValidity(Date date)
+    throws CertificateExpiredException, CertificateNotYetValidException {
+
+        CertificateValidity interval = null;
+        try {
+            interval = (CertificateValidity)info.get(CertificateValidity.NAME);
+        } catch (Exception e) {
+            throw new CertificateNotYetValidException("Incorrect validity period");
+        }
+        if (interval == null)
+            throw new CertificateNotYetValidException("Null validity period");
+        interval.valid(date);
+    }
+
+    /**
+     * Return the requested attribute from the certificate.
+     *
+     * Note that the X509CertInfo is not cloned for performance reasons.
+     * Callers must ensure that they do not modify it. All other
+     * attributes are cloned.
+     *
+     * @param name the name of the attribute.
+     * @exception CertificateParsingException on invalid attribute identifier.
+     */
+    public Object get(String name)
+    throws CertificateParsingException {
+        X509AttributeName attr = new X509AttributeName(name);
+        String id = attr.getPrefix();
+        if (!(id.equalsIgnoreCase(NAME))) {
+            throw new CertificateParsingException("Invalid root of "
+                          + "attribute name, expected [" + NAME +
+                          "], received " + "[" + id + "]");
+        }
+        attr = new X509AttributeName(attr.getSuffix());
+        id = attr.getPrefix();
+
+        if (id.equalsIgnoreCase(INFO)) {
+            if (info == null) {
+                return null;
+            }
+            if (attr.getSuffix() != null) {
+                try {
+                    return info.get(attr.getSuffix());
+                } catch (IOException e) {
+                    throw new CertificateParsingException(e.toString());
+                } catch (CertificateException e) {
+                    throw new CertificateParsingException(e.toString());
+                }
+            } else {
+                return info;
+            }
+        } else if (id.equalsIgnoreCase(ALG_ID)) {
+            return(algId);
+        } else if (id.equalsIgnoreCase(SIGNATURE)) {
+            if (signature != null)
+                return signature.clone();
+            else
+                return null;
+        } else if (id.equalsIgnoreCase(SIGNED_CERT)) {
+            if (signedCert != null)
+                return signedCert.clone();
+            else
+                return null;
+        } else {
+            throw new CertificateParsingException("Attribute name not "
+                 + "recognized or get() not allowed for the same: " + id);
+        }
+    }
+
+    /**
+     * Set the requested attribute in the certificate.
+     *
+     * @param name the name of the attribute.
+     * @param obj the value of the attribute.
+     * @exception CertificateException on invalid attribute identifier.
+     * @exception IOException on encoding error of attribute.
+     */
+    public void set(String name, Object obj)
+    throws CertificateException, IOException {
+        // check if immutable
+        if (readOnly)
+            throw new CertificateException("cannot over-write existing"
+                                           + " certificate");
+
+        X509AttributeName attr = new X509AttributeName(name);
+        String id = attr.getPrefix();
+        if (!(id.equalsIgnoreCase(NAME))) {
+            throw new CertificateException("Invalid root of attribute name,"
+                           + " expected [" + NAME + "], received " + id);
+        }
+        attr = new X509AttributeName(attr.getSuffix());
+        id = attr.getPrefix();
+
+        if (id.equalsIgnoreCase(INFO)) {
+            if (attr.getSuffix() == null) {
+                if (!(obj instanceof X509CertInfo)) {
+                    throw new CertificateException("Attribute value should"
+                                    + " be of type X509CertInfo.");
+                }
+                info = (X509CertInfo)obj;
+                signedCert = null;  //reset this as certificate data has changed
+            } else {
+                info.set(attr.getSuffix(), obj);
+                signedCert = null;  //reset this as certificate data has changed
+            }
+        } else {
+            throw new CertificateException("Attribute name not recognized or " +
+                              "set() not allowed for the same: " + id);
+        }
+    }
+
+    /**
+     * Delete the requested attribute from the certificate.
+     *
+     * @param name the name of the attribute.
+     * @exception CertificateException on invalid attribute identifier.
+     * @exception IOException on other errors.
+     */
+    public void delete(String name)
+    throws CertificateException, IOException {
+        // check if immutable
+        if (readOnly)
+            throw new CertificateException("cannot over-write existing"
+                                           + " certificate");
+
+        X509AttributeName attr = new X509AttributeName(name);
+        String id = attr.getPrefix();
+        if (!(id.equalsIgnoreCase(NAME))) {
+            throw new CertificateException("Invalid root of attribute name,"
+                                   + " expected ["
+                                   + NAME + "], received " + id);
+        }
+        attr = new X509AttributeName(attr.getSuffix());
+        id = attr.getPrefix();
+
+        if (id.equalsIgnoreCase(INFO)) {
+            if (attr.getSuffix() != null) {
+                info = null;
+            } else {
+                info.delete(attr.getSuffix());
+            }
+        } else if (id.equalsIgnoreCase(ALG_ID)) {
+            algId = null;
+        } else if (id.equalsIgnoreCase(SIGNATURE)) {
+            signature = null;
+        } else if (id.equalsIgnoreCase(SIGNED_CERT)) {
+            signedCert = null;
+        } else {
+            throw new CertificateException("Attribute name not recognized or " +
+                              "delete() not allowed for the same: " + id);
+        }
+    }
+
+    /**
+     * Return an enumeration of names of attributes existing within this
+     * attribute.
+     */
+    public Enumeration<String> getElements() {
+        AttributeNameEnumeration elements = new AttributeNameEnumeration();
+        elements.addElement(NAME + DOT + INFO);
+        elements.addElement(NAME + DOT + ALG_ID);
+        elements.addElement(NAME + DOT + SIGNATURE);
+        elements.addElement(NAME + DOT + SIGNED_CERT);
+
+        return elements.elements();
+    }
+
+    /**
+     * Return the name of this attribute.
+     */
+    public String getName() {
+        return(NAME);
+    }
+
+    /**
+     * Returns a printable representation of the certificate.  This does not
+     * contain all the information available to distinguish this from any
+     * other certificate.  The certificate must be fully constructed
+     * before this function may be called.
+     */
+    public String toString() {
+        if (info == null || algId == null || signature == null)
+            return "";
+
+        StringBuilder sb = new StringBuilder();
+
+        sb.append("[\n");
+        sb.append(info.toString() + "\n");
+        sb.append("  Algorithm: [" + algId.toString() + "]\n");
+
+        HexDumpEncoder encoder = new HexDumpEncoder();
+        sb.append("  Signature:\n" + encoder.encodeBuffer(signature));
+        sb.append("\n]");
+
+        return sb.toString();
+    }
+
+    // the strongly typed gets, as per java.security.cert.X509Certificate
+
+    /**
+     * Gets the publickey from this certificate.
+     *
+     * @return the publickey.
+     */
+    public PublicKey getPublicKey() {
+        if (info == null)
+            return null;
+        try {
+            PublicKey key = (PublicKey)info.get(CertificateX509Key.NAME
+                                + DOT + CertificateX509Key.KEY);
+            return key;
+        } catch (Exception e) {
+            return null;
+        }
+    }
+
+    /**
+     * Gets the version number from the certificate.
+     *
+     * @return the version number, i.e. 1, 2 or 3.
+     */
+    public int getVersion() {
+        if (info == null)
+            return -1;
+        try {
+            int vers = ((Integer)info.get(CertificateVersion.NAME
+                        + DOT + CertificateVersion.VERSION)).intValue();
+            return vers+1;
+        } catch (Exception e) {
+            return -1;
+        }
+    }
+
+    /**
+     * Gets the serial number from the certificate.
+     *
+     * @return the serial number.
+     */
+    public BigInteger getSerialNumber() {
+        SerialNumber ser = getSerialNumberObject();
+
+        return ser != null ? ser.getNumber() : null;
+    }
+
+    /**
+     * Gets the serial number from the certificate as
+     * a SerialNumber object.
+     *
+     * @return the serial number.
+     */
+    public SerialNumber getSerialNumberObject() {
+        if (info == null)
+            return null;
+        try {
+            SerialNumber ser = (SerialNumber)info.get(
+                              CertificateSerialNumber.NAME + DOT +
+                              CertificateSerialNumber.NUMBER);
+           return ser;
+        } catch (Exception e) {
+            return null;
+        }
+    }
+
+
+    /**
+     * Gets the subject distinguished name from the certificate.
+     *
+     * @return the subject name.
+     */
+    public Principal getSubjectDN() {
+        if (info == null)
+            return null;
+        try {
+            Principal subject = (Principal)info.get(
+                                 CertificateSubjectName.NAME + DOT +
+                                 CertificateSubjectName.DN_NAME);
+            return subject;
+        } catch (Exception e) {
+            return null;
+        }
+    }
+
+    /**
+     * Get subject name as X500Principal. Overrides implementation in
+     * X509Certificate with a slightly more efficient version that is
+     * also aware of X509CertImpl mutability.
+     */
+    public X500Principal getSubjectX500Principal() {
+        if (info == null) {
+            return null;
+        }
+        try {
+            X500Principal subject = (X500Principal)info.get(
+                                CertificateSubjectName.NAME + DOT +
+                                CertificateSubjectName.DN_PRINCIPAL);
+            return subject;
+        } catch (Exception e) {
+            return null;
+        }
+    }
+
+    /**
+     * Gets the issuer distinguished name from the certificate.
+     *
+     * @return the issuer name.
+     */
+    public Principal getIssuerDN() {
+        if (info == null)
+            return null;
+        try {
+            Principal issuer = (Principal)info.get(
+                                CertificateIssuerName.NAME + DOT +
+                                CertificateIssuerName.DN_NAME);
+            return issuer;
+        } catch (Exception e) {
+            return null;
+        }
+    }
+
+    /**
+     * Get issuer name as X500Principal. Overrides implementation in
+     * X509Certificate with a slightly more efficient version that is
+     * also aware of X509CertImpl mutability.
+     */
+    public X500Principal getIssuerX500Principal() {
+        if (info == null) {
+            return null;
+        }
+        try {
+            X500Principal issuer = (X500Principal)info.get(
+                                CertificateIssuerName.NAME + DOT +
+                                CertificateIssuerName.DN_PRINCIPAL);
+            return issuer;
+        } catch (Exception e) {
+            return null;
+        }
+    }
+
+    /**
+     * Gets the notBefore date from the validity period of the certificate.
+     *
+     * @return the start date of the validity period.
+     */
+    public Date getNotBefore() {
+        if (info == null)
+            return null;
+        try {
+            Date d = (Date) info.get(CertificateValidity.NAME + DOT +
+                                        CertificateValidity.NOT_BEFORE);
+            return d;
+        } catch (Exception e) {
+            return null;
+        }
+    }
+
+    /**
+     * Gets the notAfter date from the validity period of the certificate.
+     *
+     * @return the end date of the validity period.
+     */
+    public Date getNotAfter() {
+        if (info == null)
+            return null;
+        try {
+            Date d = (Date) info.get(CertificateValidity.NAME + DOT +
+                                     CertificateValidity.NOT_AFTER);
+            return d;
+        } catch (Exception e) {
+            return null;
+        }
+    }
+
+    /**
+     * Gets the DER encoded certificate informations, the
+     * <code>tbsCertificate</code> from this certificate.
+     * This can be used to verify the signature independently.
+     *
+     * @return the DER encoded certificate information.
+     * @exception CertificateEncodingException if an encoding error occurs.
+     */
+    public byte[] getTBSCertificate() throws CertificateEncodingException {
+        if (info != null) {
+            return info.getEncodedInfo();
+        } else
+            throw new CertificateEncodingException("Uninitialized certificate");
+    }
+
+    /**
+     * Gets the raw Signature bits from the certificate.
+     *
+     * @return the signature.
+     */
+    public byte[] getSignature() {
+        if (signature == null)
+            return null;
+        byte[] dup = new byte[signature.length];
+        System.arraycopy(signature, 0, dup, 0, dup.length);
+        return dup;
+    }
+
+    /**
+     * Gets the signature algorithm name for the certificate
+     * signature algorithm.
+     * For example, the string "SHA-1/DSA" or "DSS".
+     *
+     * @return the signature algorithm name.
+     */
+    public String getSigAlgName() {
+        if (algId == null)
+            return null;
+        return (algId.getName());
+    }
+
+    /**
+     * Gets the signature algorithm OID string from the certificate.
+     * For example, the string "1.2.840.10040.4.3"
+     *
+     * @return the signature algorithm oid string.
+     */
+    public String getSigAlgOID() {
+        if (algId == null)
+            return null;
+        ObjectIdentifier oid = algId.getOID();
+        return (oid.toString());
+    }
+
+    /**
+     * Gets the DER encoded signature algorithm parameters from this
+     * certificate's signature algorithm.
+     *
+     * @return the DER encoded signature algorithm parameters, or
+     *         null if no parameters are present.
+     */
+    public byte[] getSigAlgParams() {
+        if (algId == null)
+            return null;
+        try {
+            return algId.getEncodedParams();
+        } catch (IOException e) {
+            return null;
+        }
+    }
+
+    /**
+     * Gets the Issuer Unique Identity from the certificate.
+     *
+     * @return the Issuer Unique Identity.
+     */
+    public boolean[] getIssuerUniqueID() {
+        if (info == null)
+            return null;
+        try {
+            UniqueIdentity id = (UniqueIdentity)info.get(
+                                 CertificateIssuerUniqueIdentity.NAME
+                            + DOT + CertificateIssuerUniqueIdentity.ID);
+            if (id == null)
+                return null;
+            else
+                return (id.getId());
+        } catch (Exception e) {
+            return null;
+        }
+    }
+
+    /**
+     * Gets the Subject Unique Identity from the certificate.
+     *
+     * @return the Subject Unique Identity.
+     */
+    public boolean[] getSubjectUniqueID() {
+        if (info == null)
+            return null;
+        try {
+            UniqueIdentity id = (UniqueIdentity)info.get(
+                                 CertificateSubjectUniqueIdentity.NAME
+                            + DOT + CertificateSubjectUniqueIdentity.ID);
+            if (id == null)
+                return null;
+            else
+                return (id.getId());
+        } catch (Exception e) {
+            return null;
+        }
+    }
+
+    /**
+     * Get AuthorityKeyIdentifier extension
+     * @return AuthorityKeyIdentifier object or null (if no such object
+     * in certificate)
+     */
+    public AuthorityKeyIdentifierExtension getAuthorityKeyIdentifierExtension()
+    {
+        return (AuthorityKeyIdentifierExtension)
+            getExtension(PKIXExtensions.AuthorityKey_Id);
+    }
+
+    /**
+     * Get BasicConstraints extension
+     * @return BasicConstraints object or null (if no such object in
+     * certificate)
+     */
+    public BasicConstraintsExtension getBasicConstraintsExtension() {
+        return (BasicConstraintsExtension)
+            getExtension(PKIXExtensions.BasicConstraints_Id);
+    }
+
+    /**
+     * Get CertificatePoliciesExtension
+     * @return CertificatePoliciesExtension or null (if no such object in
+     * certificate)
+     */
+    public CertificatePoliciesExtension getCertificatePoliciesExtension() {
+        return (CertificatePoliciesExtension)
+            getExtension(PKIXExtensions.CertificatePolicies_Id);
+    }
+
+    /**
+     * Get ExtendedKeyUsage extension
+     * @return ExtendedKeyUsage extension object or null (if no such object
+     * in certificate)
+     */
+    public ExtendedKeyUsageExtension getExtendedKeyUsageExtension() {
+        return (ExtendedKeyUsageExtension)
+            getExtension(PKIXExtensions.ExtendedKeyUsage_Id);
+    }
+
+    /**
+     * Get IssuerAlternativeName extension
+     * @return IssuerAlternativeName object or null (if no such object in
+     * certificate)
+     */
+    public IssuerAlternativeNameExtension getIssuerAlternativeNameExtension() {
+        return (IssuerAlternativeNameExtension)
+            getExtension(PKIXExtensions.IssuerAlternativeName_Id);
+    }
+
+    /**
+     * Get NameConstraints extension
+     * @return NameConstraints object or null (if no such object in certificate)
+     */
+    public NameConstraintsExtension getNameConstraintsExtension() {
+        return (NameConstraintsExtension)
+            getExtension(PKIXExtensions.NameConstraints_Id);
+    }
+
+    /**
+     * Get PolicyConstraints extension
+     * @return PolicyConstraints object or null (if no such object in
+     * certificate)
+     */
+    public PolicyConstraintsExtension getPolicyConstraintsExtension() {
+        return (PolicyConstraintsExtension)
+            getExtension(PKIXExtensions.PolicyConstraints_Id);
+    }
+
+    /**
+     * Get PolicyMappingsExtension extension
+     * @return PolicyMappingsExtension object or null (if no such object
+     * in certificate)
+     */
+    public PolicyMappingsExtension getPolicyMappingsExtension() {
+        return (PolicyMappingsExtension)
+            getExtension(PKIXExtensions.PolicyMappings_Id);
+    }
+
+    /**
+     * Get PrivateKeyUsage extension
+     * @return PrivateKeyUsage object or null (if no such object in certificate)
+     */
+    public PrivateKeyUsageExtension getPrivateKeyUsageExtension() {
+        return (PrivateKeyUsageExtension)
+            getExtension(PKIXExtensions.PrivateKeyUsage_Id);
+    }
+
+    /**
+     * Get SubjectAlternativeName extension
+     * @return SubjectAlternativeName object or null (if no such object in
+     * certificate)
+     */
+    public SubjectAlternativeNameExtension getSubjectAlternativeNameExtension()
+    {
+        return (SubjectAlternativeNameExtension)
+            getExtension(PKIXExtensions.SubjectAlternativeName_Id);
+    }
+
+    /**
+     * Get SubjectKeyIdentifier extension
+     * @return SubjectKeyIdentifier object or null (if no such object in
+     * certificate)
+     */
+    public SubjectKeyIdentifierExtension getSubjectKeyIdentifierExtension() {
+        return (SubjectKeyIdentifierExtension)
+            getExtension(PKIXExtensions.SubjectKey_Id);
+    }
+
+    /**
+     * Get CRLDistributionPoints extension
+     * @return CRLDistributionPoints object or null (if no such object in
+     * certificate)
+     */
+    public CRLDistributionPointsExtension getCRLDistributionPointsExtension() {
+        return (CRLDistributionPointsExtension)
+            getExtension(PKIXExtensions.CRLDistributionPoints_Id);
+    }
+
+    /**
+     * Return true if a critical extension is found that is
+     * not supported, otherwise return false.
+     */
+    public boolean hasUnsupportedCriticalExtension() {
+        if (info == null)
+            return false;
+        try {
+            CertificateExtensions exts = (CertificateExtensions)info.get(
+                                         CertificateExtensions.NAME);
+            if (exts == null)
+                return false;
+            return exts.hasUnsupportedCriticalExtension();
+        } catch (Exception e) {
+            return false;
+        }
+    }
+
+    /**
+     * Gets a Set of the extension(s) marked CRITICAL in the
+     * certificate. In the returned set, each extension is
+     * represented by its OID string.
+     *
+     * @return a set of the extension oid strings in the
+     * certificate that are marked critical.
+     */
+    public Set<String> getCriticalExtensionOIDs() {
+        if (info == null) {
+            return null;
+        }
+        try {
+            CertificateExtensions exts = (CertificateExtensions)info.get(
+                                         CertificateExtensions.NAME);
+            if (exts == null) {
+                return null;
+            }
+            Set<String> extSet = new HashSet<String>();
+            for (Extension ex : exts.getAllExtensions()) {
+                if (ex.isCritical()) {
+                    extSet.add(ex.getExtensionId().toString());
+                }
+            }
+            return extSet;
+        } catch (Exception e) {
+            return null;
+        }
+    }
+
+    /**
+     * Gets a Set of the extension(s) marked NON-CRITICAL in the
+     * certificate. In the returned set, each extension is
+     * represented by its OID string.
+     *
+     * @return a set of the extension oid strings in the
+     * certificate that are NOT marked critical.
+     */
+    public Set<String> getNonCriticalExtensionOIDs() {
+        if (info == null) {
+            return null;
+        }
+        try {
+            CertificateExtensions exts = (CertificateExtensions)info.get(
+                                         CertificateExtensions.NAME);
+            if (exts == null) {
+                return null;
+            }
+            Set<String> extSet = new HashSet<String>();
+            for (Extension ex : exts.getAllExtensions()) {
+                if (!ex.isCritical()) {
+                    extSet.add(ex.getExtensionId().toString());
+                }
+            }
+            extSet.addAll(exts.getUnparseableExtensions().keySet());
+            return extSet;
+        } catch (Exception e) {
+            return null;
+        }
+    }
+
+    /**
+     * Gets the extension identified by the given ObjectIdentifier
+     *
+     * @param oid the Object Identifier value for the extension.
+     * @return Extension or null if certificate does not contain this
+     *         extension
+     */
+    public Extension getExtension(ObjectIdentifier oid) {
+        if (info == null) {
+            return null;
+        }
+        try {
+            CertificateExtensions extensions;
+            try {
+                extensions = (CertificateExtensions)info.get(CertificateExtensions.NAME);
+            } catch (CertificateException ce) {
+                return null;
+            }
+            if (extensions == null) {
+                return null;
+            } else {
+                for (Extension ex : extensions.getAllExtensions()) {
+                    if (ex.getExtensionId().equals(oid)) {
+                        //XXXX May want to consider cloning this
+                        return ex;
+                    }
+                }
+                /* no such extension in this certificate */
+                return null;
+            }
+        } catch (IOException ioe) {
+            return null;
+        }
+    }
+
+    public Extension getUnparseableExtension(ObjectIdentifier oid) {
+        if (info == null) {
+            return null;
+        }
+        try {
+            CertificateExtensions extensions;
+            try {
+                extensions = (CertificateExtensions)info.get(CertificateExtensions.NAME);
+            } catch (CertificateException ce) {
+                return null;
+            }
+            if (extensions == null) {
+                return null;
+            } else {
+                return extensions.getUnparseableExtensions().get(oid.toString());
+            }
+        } catch (IOException ioe) {
+            return null;
+        }
+    }
+
+    /**
+     * Gets the DER encoded extension identified by the given
+     * oid String.
+     *
+     * @param oid the Object Identifier value for the extension.
+     */
+    public byte[] getExtensionValue(String oid) {
+        try {
+            ObjectIdentifier findOID = new ObjectIdentifier(oid);
+            String extAlias = OIDMap.getName(findOID);
+            Extension certExt = null;
+            CertificateExtensions exts = (CertificateExtensions)info.get(
+                                     CertificateExtensions.NAME);
+
+            if (extAlias == null) { // may be unknown
+                // get the extensions, search thru' for this oid
+                if (exts == null) {
+                    return null;
+                }
+
+                for (Extension ex : exts.getAllExtensions()) {
+                    ObjectIdentifier inCertOID = ex.getExtensionId();
+                    if (inCertOID.equals(findOID)) {
+                        certExt = ex;
+                        break;
+                    }
+                }
+            } else { // there's sub-class that can handle this extension
+                try {
+                    certExt = (Extension)this.get(extAlias);
+                } catch (CertificateException e) {
+                    // get() throws an Exception instead of returning null, ignore
+                }
+            }
+            if (certExt == null) {
+                if (exts != null) {
+                    certExt = exts.getUnparseableExtensions().get(oid);
+                }
+                if (certExt == null) {
+                    return null;
+                }
+            }
+            byte[] extData = certExt.getExtensionValue();
+            if (extData == null) {
+                return null;
+            }
+            DerOutputStream out = new DerOutputStream();
+            out.putOctetString(extData);
+            return out.toByteArray();
+        } catch (Exception e) {
+            return null;
+        }
+    }
+
+    /**
+     * Get a boolean array representing the bits of the KeyUsage extension,
+     * (oid = 2.5.29.15).
+     * @return the bit values of this extension as an array of booleans.
+     */
+    public boolean[] getKeyUsage() {
+        try {
+            String extAlias = OIDMap.getName(PKIXExtensions.KeyUsage_Id);
+            if (extAlias == null)
+                return null;
+
+            KeyUsageExtension certExt = (KeyUsageExtension)this.get(extAlias);
+            if (certExt == null)
+                return null;
+
+            boolean[] ret = certExt.getBits();
+            if (ret.length < NUM_STANDARD_KEY_USAGE) {
+                boolean[] usageBits = new boolean[NUM_STANDARD_KEY_USAGE];
+                System.arraycopy(ret, 0, usageBits, 0, ret.length);
+                ret = usageBits;
+            }
+            return ret;
+        } catch (Exception e) {
+            return null;
+        }
+    }
+
+    /**
+     * This method are the overridden implementation of
+     * getExtendedKeyUsage method in X509Certificate in the Sun
+     * provider. It is better performance-wise since it returns cached
+     * values.
+     */
+    public synchronized List<String> getExtendedKeyUsage()
+        throws CertificateParsingException {
+        if (readOnly && extKeyUsage != null) {
+            return extKeyUsage;
+        } else {
+            ExtendedKeyUsageExtension ext = getExtendedKeyUsageExtension();
+            if (ext == null) {
+                return null;
+            }
+            extKeyUsage =
+                Collections.unmodifiableList(ext.getExtendedKeyUsage());
+            return extKeyUsage;
+        }
+    }
+
+    /**
+     * This static method is the default implementation of the
+     * getExtendedKeyUsage method in X509Certificate. A
+     * X509Certificate provider generally should overwrite this to
+     * provide among other things caching for better performance.
+     */
+    public static List<String> getExtendedKeyUsage(X509Certificate cert)
+        throws CertificateParsingException {
+        try {
+            byte[] ext = cert.getExtensionValue(EXTENDED_KEY_USAGE_OID);
+            if (ext == null)
+                return null;
+            DerValue val = new DerValue(ext);
+            byte[] data = val.getOctetString();
+
+            ExtendedKeyUsageExtension ekuExt =
+                new ExtendedKeyUsageExtension(Boolean.FALSE, data);
+            return Collections.unmodifiableList(ekuExt.getExtendedKeyUsage());
+        } catch (IOException ioe) {
+            CertificateParsingException cpe =
+                new CertificateParsingException();
+            cpe.initCause(ioe);
+            throw cpe;
+        }
+    }
+
+    /**
+     * Get the certificate constraints path length from the
+     * the critical BasicConstraints extension, (oid = 2.5.29.19).
+     * @return the length of the constraint.
+     */
+    public int getBasicConstraints() {
+        try {
+            String extAlias = OIDMap.getName(PKIXExtensions.BasicConstraints_Id);
+            if (extAlias == null)
+                return -1;
+            BasicConstraintsExtension certExt =
+                        (BasicConstraintsExtension)this.get(extAlias);
+            if (certExt == null)
+                return -1;
+
+            if (((Boolean)certExt.get(BasicConstraintsExtension.IS_CA)
+                 ).booleanValue() == true)
+                return ((Integer)certExt.get(
+                        BasicConstraintsExtension.PATH_LEN)).intValue();
+            else
+                return -1;
+        } catch (Exception e) {
+            return -1;
+        }
+    }
+
+    /**
+     * Converts a GeneralNames structure into an immutable Collection of
+     * alternative names (subject or issuer) in the form required by
+     * {@link #getSubjectAlternativeNames} or
+     * {@link #getIssuerAlternativeNames}.
+     *
+     * @param names the GeneralNames to be converted
+     * @return an immutable Collection of alternative names
+     */
+    private static Collection<List<?>> makeAltNames(GeneralNames names) {
+        if (names.isEmpty()) {
+            return Collections.<List<?>>emptySet();
+        }
+        Set<List<?>> newNames = new HashSet<List<?>>();
+        for (GeneralName gname : names.names()) {
+            GeneralNameInterface name = gname.getName();
+            List<Object> nameEntry = new ArrayList<Object>(2);
+            nameEntry.add(Integer.valueOf(name.getType()));
+            switch (name.getType()) {
+            case GeneralNameInterface.NAME_RFC822:
+                nameEntry.add(((RFC822Name) name).getName());
+                break;
+            case GeneralNameInterface.NAME_DNS:
+                nameEntry.add(((DNSName) name).getName());
+                break;
+            case GeneralNameInterface.NAME_DIRECTORY:
+                nameEntry.add(((X500Name) name).getRFC2253Name());
+                break;
+            case GeneralNameInterface.NAME_URI:
+                nameEntry.add(((URIName) name).getName());
+                break;
+            case GeneralNameInterface.NAME_IP:
+                try {
+                    nameEntry.add(((IPAddressName) name).getName());
+                } catch (IOException ioe) {
+                    // IPAddressName in cert is bogus
+                    throw new RuntimeException("IPAddress cannot be parsed",
+                        ioe);
+                }
+                break;
+            case GeneralNameInterface.NAME_OID:
+                nameEntry.add(((OIDName) name).getOID().toString());
+                break;
+            default:
+                // add DER encoded form
+                DerOutputStream derOut = new DerOutputStream();
+                try {
+                    name.encode(derOut);
+                } catch (IOException ioe) {
+                    // should not occur since name has already been decoded
+                    // from cert (this would indicate a bug in our code)
+                    throw new RuntimeException("name cannot be encoded", ioe);
+                }
+                nameEntry.add(derOut.toByteArray());
+                break;
+            }
+            newNames.add(Collections.unmodifiableList(nameEntry));
+        }
+        return Collections.unmodifiableCollection(newNames);
+    }
+
+    /**
+     * Checks a Collection of altNames and clones any name entries of type
+     * byte [].
+     */ // only partially generified due to javac bug
+    private static Collection<List<?>> cloneAltNames(Collection<List<?>> altNames) {
+        boolean mustClone = false;
+        for (List<?> nameEntry : altNames) {
+            if (nameEntry.get(1) instanceof byte[]) {
+                // must clone names
+                mustClone = true;
+            }
+        }
+        if (mustClone) {
+            Set<List<?>> namesCopy = new HashSet<List<?>>();
+            for (List<?> nameEntry : altNames) {
+                Object nameObject = nameEntry.get(1);
+                if (nameObject instanceof byte[]) {
+                    List<Object> nameEntryCopy =
+                                        new ArrayList<Object>(nameEntry);
+                    nameEntryCopy.set(1, ((byte[])nameObject).clone());
+                    namesCopy.add(Collections.unmodifiableList(nameEntryCopy));
+                } else {
+                    namesCopy.add(nameEntry);
+                }
+            }
+            return Collections.unmodifiableCollection(namesCopy);
+        } else {
+            return altNames;
+        }
+    }
+
+    /**
+     * This method are the overridden implementation of
+     * getSubjectAlternativeNames method in X509Certificate in the Sun
+     * provider. It is better performance-wise since it returns cached
+     * values.
+     */
+    public synchronized Collection<List<?>> getSubjectAlternativeNames()
+        throws CertificateParsingException {
+        // return cached value if we can
+        if (readOnly && subjectAlternativeNames != null)  {
+            return cloneAltNames(subjectAlternativeNames);
+        }
+        SubjectAlternativeNameExtension subjectAltNameExt =
+            getSubjectAlternativeNameExtension();
+        if (subjectAltNameExt == null) {
+            return null;
+        }
+        GeneralNames names;
+        try {
+            names = (GeneralNames) subjectAltNameExt.get
+                (SubjectAlternativeNameExtension.SUBJECT_NAME);
+        } catch (IOException ioe) {
+            // should not occur
+            return Collections.<List<?>>emptySet();
+        }
+        subjectAlternativeNames = makeAltNames(names);
+        return subjectAlternativeNames;
+    }
+
+    /**
+     * This static method is the default implementation of the
+     * getSubjectAlternaitveNames method in X509Certificate. A
+     * X509Certificate provider generally should overwrite this to
+     * provide among other things caching for better performance.
+     */
+    public static Collection<List<?>> getSubjectAlternativeNames(X509Certificate cert)
+        throws CertificateParsingException {
+        try {
+            byte[] ext = cert.getExtensionValue(SUBJECT_ALT_NAME_OID);
+            if (ext == null) {
+                return null;
+            }
+            DerValue val = new DerValue(ext);
+            byte[] data = val.getOctetString();
+
+            SubjectAlternativeNameExtension subjectAltNameExt =
+                new SubjectAlternativeNameExtension(Boolean.FALSE,
+                                                    data);
+
+            GeneralNames names;
+            try {
+                names = (GeneralNames) subjectAltNameExt.get
+                    (SubjectAlternativeNameExtension.SUBJECT_NAME);
+            }  catch (IOException ioe) {
+                // should not occur
+                return Collections.<List<?>>emptySet();
+            }
+            return makeAltNames(names);
+        } catch (IOException ioe) {
+            CertificateParsingException cpe =
+                new CertificateParsingException();
+            cpe.initCause(ioe);
+            throw cpe;
+        }
+    }
+
+    /**
+     * This method are the overridden implementation of
+     * getIssuerAlternativeNames method in X509Certificate in the Sun
+     * provider. It is better performance-wise since it returns cached
+     * values.
+     */
+    public synchronized Collection<List<?>> getIssuerAlternativeNames()
+        throws CertificateParsingException {
+        // return cached value if we can
+        if (readOnly && issuerAlternativeNames != null) {
+            return cloneAltNames(issuerAlternativeNames);
+        }
+        IssuerAlternativeNameExtension issuerAltNameExt =
+            getIssuerAlternativeNameExtension();
+        if (issuerAltNameExt == null) {
+            return null;
+        }
+        GeneralNames names;
+        try {
+            names = (GeneralNames) issuerAltNameExt.get
+                (IssuerAlternativeNameExtension.ISSUER_NAME);
+        } catch (IOException ioe) {
+            // should not occur
+            return Collections.<List<?>>emptySet();
+        }
+        issuerAlternativeNames = makeAltNames(names);
+        return issuerAlternativeNames;
+    }
+
+    /**
+     * This static method is the default implementation of the
+     * getIssuerAlternaitveNames method in X509Certificate. A
+     * X509Certificate provider generally should overwrite this to
+     * provide among other things caching for better performance.
+     */
+    public static Collection<List<?>> getIssuerAlternativeNames(X509Certificate cert)
+        throws CertificateParsingException {
+        try {
+            byte[] ext = cert.getExtensionValue(ISSUER_ALT_NAME_OID);
+            if (ext == null) {
+                return null;
+            }
+
+            DerValue val = new DerValue(ext);
+            byte[] data = val.getOctetString();
+
+            IssuerAlternativeNameExtension issuerAltNameExt =
+                new IssuerAlternativeNameExtension(Boolean.FALSE,
+                                                    data);
+            GeneralNames names;
+            try {
+                names = (GeneralNames) issuerAltNameExt.get
+                    (IssuerAlternativeNameExtension.ISSUER_NAME);
+            }  catch (IOException ioe) {
+                // should not occur
+                return Collections.<List<?>>emptySet();
+            }
+            return makeAltNames(names);
+        } catch (IOException ioe) {
+            CertificateParsingException cpe =
+                new CertificateParsingException();
+            cpe.initCause(ioe);
+            throw cpe;
+        }
+    }
+
+    public AuthorityInfoAccessExtension getAuthorityInfoAccessExtension() {
+        return (AuthorityInfoAccessExtension)
+            getExtension(PKIXExtensions.AuthInfoAccess_Id);
+    }
+
+    /************************************************************/
+
+    /*
+     * Cert is a SIGNED ASN.1 macro, a three elment sequence:
+     *
+     *  - Data to be signed (ToBeSigned) -- the "raw" cert
+     *  - Signature algorithm (SigAlgId)
+     *  - The signature bits
+     *
+     * This routine unmarshals the certificate, saving the signature
+     * parts away for later verification.
+     */
+    private void parse(DerValue val)
+    throws CertificateException, IOException {
+        // check if can over write the certificate
+        if (readOnly)
+            throw new CertificateParsingException(
+                      "cannot over-write existing certificate");
+
+        if (val.data == null || val.tag != DerValue.tag_Sequence)
+            throw new CertificateParsingException(
+                      "invalid DER-encoded certificate data");
+
+        signedCert = val.toByteArray();
+        DerValue[] seq = new DerValue[3];
+
+        seq[0] = val.data.getDerValue();
+        seq[1] = val.data.getDerValue();
+        seq[2] = val.data.getDerValue();
+
+        if (val.data.available() != 0) {
+            throw new CertificateParsingException("signed overrun, bytes = "
+                                     + val.data.available());
+        }
+        if (seq[0].tag != DerValue.tag_Sequence) {
+            throw new CertificateParsingException("signed fields invalid");
+        }
+
+        algId = AlgorithmId.parse(seq[1]);
+        signature = seq[2].getBitString();
+
+        if (seq[1].data.available() != 0) {
+            throw new CertificateParsingException("algid field overrun");
+        }
+        if (seq[2].data.available() != 0)
+            throw new CertificateParsingException("signed fields overrun");
+
+        // The CertificateInfo
+        info = new X509CertInfo(seq[0]);
+
+        // the "inner" and "outer" signature algorithms must match
+        AlgorithmId infoSigAlg = (AlgorithmId)info.get(
+                                              CertificateAlgorithmId.NAME
+                                              + DOT +
+                                              CertificateAlgorithmId.ALGORITHM);
+        if (! algId.equals(infoSigAlg))
+            throw new CertificateException("Signature algorithm mismatch");
+        readOnly = true;
+    }
+
+    /**
+     * Extract the subject or issuer X500Principal from an X509Certificate.
+     * Parses the encoded form of the cert to preserve the principal's
+     * ASN.1 encoding.
+     */
+    private static X500Principal getX500Principal(X509Certificate cert,
+            boolean getIssuer) throws Exception {
+        byte[] encoded = cert.getEncoded();
+        DerInputStream derIn = new DerInputStream(encoded);
+        DerValue tbsCert = derIn.getSequence(3)[0];
+        DerInputStream tbsIn = tbsCert.data;
+        DerValue tmp;
+        tmp = tbsIn.getDerValue();
+        // skip version number if present
+        if (tmp.isContextSpecific((byte)0)) {
+          tmp = tbsIn.getDerValue();
+        }
+        // tmp always contains serial number now
+        tmp = tbsIn.getDerValue();              // skip signature
+        tmp = tbsIn.getDerValue();              // issuer
+        if (getIssuer == false) {
+            tmp = tbsIn.getDerValue();          // skip validity
+            tmp = tbsIn.getDerValue();          // subject
+        }
+        byte[] principalBytes = tmp.toByteArray();
+        return new X500Principal(principalBytes);
+    }
+
+    /**
+     * Extract the subject X500Principal from an X509Certificate.
+     * Called from java.security.cert.X509Certificate.getSubjectX500Principal().
+     */
+    public static X500Principal getSubjectX500Principal(X509Certificate cert) {
+        try {
+            return getX500Principal(cert, false);
+        } catch (Exception e) {
+            throw new RuntimeException("Could not parse subject", e);
+        }
+    }
+
+    /**
+     * Extract the issuer X500Principal from an X509Certificate.
+     * Called from java.security.cert.X509Certificate.getIssuerX500Principal().
+     */
+    public static X500Principal getIssuerX500Principal(X509Certificate cert) {
+        try {
+            return getX500Principal(cert, true);
+        } catch (Exception e) {
+            throw new RuntimeException("Could not parse issuer", e);
+        }
+    }
+
+    /**
+     * Returned the encoding of the given certificate for internal use.
+     * Callers must guarantee that they neither modify it nor expose it
+     * to untrusted code. Uses getEncodedInternal() if the certificate
+     * is instance of X509CertImpl, getEncoded() otherwise.
+     */
+    public static byte[] getEncodedInternal(Certificate cert)
+            throws CertificateEncodingException {
+        if (cert instanceof X509CertImpl) {
+            return ((X509CertImpl)cert).getEncodedInternal();
+        } else {
+            return cert.getEncoded();
+        }
+    }
+
+    /**
+     * Utility method to convert an arbitrary instance of X509Certificate
+     * to a X509CertImpl. Does a cast if possible, otherwise reparses
+     * the encoding.
+     */
+    public static X509CertImpl toImpl(X509Certificate cert)
+            throws CertificateException {
+        if (cert instanceof X509CertImpl) {
+            return (X509CertImpl)cert;
+        } else {
+            return X509Factory.intern(cert);
+        }
+    }
+
+    /**
+     * Utility method to test if a certificate is self-issued. This is
+     * the case iff the subject and issuer X500Principals are equal.
+     */
+    public static boolean isSelfIssued(X509Certificate cert) {
+        X500Principal subject = cert.getSubjectX500Principal();
+        X500Principal issuer = cert.getIssuerX500Principal();
+        return subject.equals(issuer);
+    }
+
+    /**
+     * Utility method to test if a certificate is self-signed. This is
+     * the case iff the subject and issuer X500Principals are equal
+     * AND the certificate's subject public key can be used to verify
+     * the certificate. In case of exception, returns false.
+     */
+    public static boolean isSelfSigned(X509Certificate cert,
+        String sigProvider) {
+        if (isSelfIssued(cert)) {
+            try {
+                if (sigProvider == null) {
+                    cert.verify(cert.getPublicKey());
+                } else {
+                    cert.verify(cert.getPublicKey(), sigProvider);
+                }
+                return true;
+            } catch (Exception e) {
+                // In case of exception, return false
+            }
+        }
+        return false;
+    }
+}