/*

 * Copyright (c) 1996, 2007, 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

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 */

package sun.security.ssl;

import java.util.Arrays;

import java.security.*;

/**

 * Signature implementation for the SSL/TLS RSA Signature variant with both

 * MD5 and SHA-1 MessageDigests. Used for explicit RSA server authentication

 * (RSA signed server key exchange for RSA_EXPORT and DHE_RSA) and RSA client

 * authentication (RSA signed certificate verify message).

 *

 * It conforms to the standard JCA Signature API. It is registered in the

 * SunJSSE provider to avoid more complicated getInstance() code and

 * negative interaction with the JCA mechanisms for hardware providers.

 *

 * The class should be instantiated via the getInstance() method in this class,

 * which returns the implementation from the prefered provider. The internal

 * implementation allows the hashes to be explicitly set, which is required

 * for RSA client authentication. It can be obtained via the

 * getInternalInstance() method.

 *

 * This class is not thread safe.

 *

 */

public final class RSASignature extends SignatureSpi {

    private final Signature rawRsa;

    private MessageDigest md5, sha;

    // flag indicating if the MessageDigests are in reset state

    private boolean isReset;

    public RSASignature() throws NoSuchAlgorithmException {

        super();

        rawRsa = JsseJce.getSignature(JsseJce.SIGNATURE_RAWRSA);

        isReset = true;

    }

    /**

     * Get an implementation for the RSA signature. Follows the standard

     * JCA getInstance() model, so it return the implementation from the

     * provider with the highest precedence, which may be this class.

     */

    static Signature getInstance() throws NoSuchAlgorithmException {

        return JsseJce.getSignature(JsseJce.SIGNATURE_SSLRSA);

    }

    /**

     * Get an internal implementation for the RSA signature. Used for RSA

     * client authentication, which needs the ability to set the digests

     * to externally provided values via the setHashes() method.

     */

    static Signature getInternalInstance()

            throws NoSuchAlgorithmException, NoSuchProviderException {

        return Signature.getInstance(JsseJce.SIGNATURE_SSLRSA, "SunJSSE");

    }

    /**

     * Set the MD5 and SHA hashes to the provided objects.

     */

    static void setHashes(Signature sig, MessageDigest md5, MessageDigest sha) {

        sig.setParameter("hashes", new MessageDigest[] {md5, sha});

    }

    /**

     * Reset the MessageDigests unless they are already reset.

     */

    private void reset() {

        if (isReset == false) {

            md5.reset();

            sha.reset();

            isReset = true;

        }

    }

    private static void checkNull(Key key) throws InvalidKeyException {

        if (key == null) {

            throw new InvalidKeyException("Key must not be null");

        }

    }

    protected void engineInitVerify(PublicKey publicKey)

            throws InvalidKeyException {

        checkNull(publicKey);

        reset();

        rawRsa.initVerify(publicKey);

    }

    protected void engineInitSign(PrivateKey privateKey)

            throws InvalidKeyException {

        engineInitSign(privateKey, null);

    }

    protected void engineInitSign(PrivateKey privateKey, SecureRandom random)

            throws InvalidKeyException {

        checkNull(privateKey);

        reset();

        rawRsa.initSign(privateKey, random);

    }

    // lazily initialize the MessageDigests

    private void initDigests() {

        if (md5 == null) {

            md5 = JsseJce.getMD5();

            sha = JsseJce.getSHA();

        }

    }

    protected void engineUpdate(byte b) {

        initDigests();

        isReset = false;

        md5.update(b);

        sha.update(b);

    }

    protected void engineUpdate(byte[] b, int off, int len) {

        initDigests();

        isReset = false;

        md5.update(b, off, len);

        sha.update(b, off, len);

    }

    private byte[] getDigest() throws SignatureException {

        try {

            initDigests();

            byte[] data = new byte[36];

            md5.digest(data, 0, 16);

            sha.digest(data, 16, 20);

            isReset = true;

            return data;

        } catch (DigestException e) {

            // should never occur

            throw new SignatureException(e);

        }

    }

    protected byte[] engineSign() throws SignatureException {

        rawRsa.update(getDigest());

        return rawRsa.sign();

    }

    protected boolean engineVerify(byte[] sigBytes) throws SignatureException {

        return engineVerify(sigBytes, 0, sigBytes.length);

    }

    protected boolean engineVerify(byte[] sigBytes, int offset, int length)

            throws SignatureException {

        rawRsa.update(getDigest());

        return rawRsa.verify(sigBytes, offset, length);

    }

    protected void engineSetParameter(String param, Object value)

            throws InvalidParameterException {

        if (param.equals("hashes") == false) {

            throw new InvalidParameterException

                ("Parameter not supported: " + param);

        }

        if (value instanceof MessageDigest[] == false) {

            throw new InvalidParameterException

                ("value must be MessageDigest[]");

        }

        MessageDigest[] digests = (MessageDigest[])value;

        md5 = digests[0];

        sha = digests[1];

    }

    protected Object engineGetParameter(String param)

            throws InvalidParameterException {

        throw new InvalidParameterException("Parameters not supported");

    }

}