/*

 * Copyright (c) 1996, 2011, Oracle and/or its affiliates. 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.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.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;

            throw new CertificateException("Unable to initialize, " + e, e);

        }

    }

    /**

     * 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) {

                throw new CertificateException("Input stream must be " +

                                               "either DER-encoded bytes " +

                                               "or RFC1421 hex-encoded " +

                                               "DER-encoded bytes: " +

                                               ioe1.getMessage(), ioe1);

            }

        }

        try {

            parse(der);

        } catch (IOException ioe) {

            signedCert = null;

            throw new CertificateException("Unable to parse DER value of " +

                                           "certificate, " + ioe, ioe);

        }

    }

    /**

     * 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;

            throw new CertificateException("Unable to initialize, " + e, e);

        }

    }

    /**

     * 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.