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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
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package sun.security.ssl;

import java.security.*;
import java.security.spec.AlgorithmParameterSpec;

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 preferred 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.
/**
 * 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 preferred 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 final MessageDigest mdMD5;
    private final MessageDigest mdSHA;

    public RSASignature() throws NoSuchAlgorithmException {
        super();
        rawRsa = JsseJce.getSignature(JsseJce.SIGNATURE_RAWRSA);
        this.mdMD5 = JsseJce.getMessageDigest("MD5");
        this.mdSHA = JsseJce.getMessageDigest("SHA");
    }

    
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.
/**
     * 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);
    }

    @Override
    protected void engineInitVerify(PublicKey publicKey)
            throws InvalidKeyException {
        if (publicKey == null) {
            throw new InvalidKeyException("Public key must not be null");
        }
        mdMD5.reset();
        mdSHA.reset();
        rawRsa.initVerify(publicKey);
    }

    @Override
    protected void engineInitSign(PrivateKey privateKey)
            throws InvalidKeyException {
        engineInitSign(privateKey, null);
    }

    @Override
    protected void engineInitSign(PrivateKey privateKey, SecureRandom random)
            throws InvalidKeyException {
        if (privateKey == null) {
            throw new InvalidKeyException("Private key must not be null");
        }
        mdMD5.reset();
        mdSHA.reset();
        rawRsa.initSign(privateKey, random);
    }

    @Override
    protected void engineUpdate(byte b) {
        mdMD5.update(b);
        mdSHA.update(b);
    }

    @Override
    protected void engineUpdate(byte[] b, int off, int len) {
        mdMD5.update(b, off, len);
        mdSHA.update(b, off, len);
    }

    private byte[] getDigest() throws SignatureException {
        try {
            byte[] data = new byte[36];
            mdMD5.digest(data, 0, 16);
            mdSHA.digest(data, 16, 20);
            return data;
        } catch (DigestException e) {
            // should never occur
            throw new SignatureException(e);
        }
    }

    @Override
    protected byte[] engineSign() throws SignatureException {
        rawRsa.update(getDigest());
        return rawRsa.sign();
    }

    @Override
    protected boolean engineVerify(byte[] sigBytes) throws SignatureException {
        return engineVerify(sigBytes, 0, sigBytes.length);
    }

    @Override
    protected boolean engineVerify(byte[] sigBytes, int offset, int length)
            throws SignatureException {
        rawRsa.update(getDigest());
        return rawRsa.verify(sigBytes, offset, length);
    }

    @Override
    @SuppressWarnings("deprecation")
    protected void engineSetParameter(String param,
            Object value) throws InvalidParameterException {
        throw new InvalidParameterException("Parameters not supported");
    }

    @Override
    protected void engineSetParameter(AlgorithmParameterSpec params)
            throws InvalidAlgorithmParameterException {
        if (params != null) {
            throw new InvalidAlgorithmParameterException("No parameters accepted");
        }
    }

    @Override
    @SuppressWarnings("deprecation")
    protected Object engineGetParameter(
            String param) throws InvalidParameterException {
        throw new InvalidParameterException("Parameters not supported");
    }

    @Override
    protected AlgorithmParameters engineGetParameters() {
        return null;
    }
}