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 * Copyright (c) 2014, 2015, 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 com.oracle.security.ucrypto;

import java.util.Set;

import java.util.Arrays;

import java.util.concurrent.ConcurrentSkipListSet;

import java.lang.ref.*;

import java.math.BigInteger;

import java.nio.ByteBuffer;

import java.security.SignatureSpi;

import java.security.NoSuchAlgorithmException;

import java.security.InvalidParameterException;

import java.security.InvalidKeyException;

import java.security.SignatureException;

import java.security.Key;

import java.security.PrivateKey;

import java.security.PublicKey;

import java.security.*;

import java.security.interfaces.*;

import java.security.spec.RSAPrivateCrtKeySpec;

import java.security.spec.RSAPublicKeySpec;

import java.security.spec.InvalidKeySpecException;

import sun.nio.ch.DirectBuffer;

import java.nio.ByteBuffer;

/**

 * Signature implementation class. This class currently supports the

 * following algorithms:

 *

 * . RSA:

 *   . MD5withRSA

 *   . SHA1withRSA

 *   . SHA256withRSA

 *   . SHA384withRSA

 *   . SHA512withRSA

 *

 * @since 1.9

 */

class NativeRSASignature extends SignatureSpi {

    private static final int PKCS1PADDING_LEN = 11;

    // fields set in constructor

    private final UcryptoMech mech;

    private final int encodedLen;

    // field for ensuring native memory is freed

    private SignatureContextRef pCtxt = null;

    //

    // fields (re)set in every init()

    //

    private boolean initialized = false;

    private boolean sign = true;

    private int sigLength;

    private NativeKey key;

    private NativeRSAKeyFactory keyFactory; // may need a more generic type later

    // public implementation classes

    public static final class MD5 extends NativeRSASignature {

        public MD5() throws NoSuchAlgorithmException {

            super(UcryptoMech.CRYPTO_MD5_RSA_PKCS, 34);

        }

    }

    public static final class SHA1 extends NativeRSASignature {

        public SHA1() throws NoSuchAlgorithmException {

            super(UcryptoMech.CRYPTO_SHA1_RSA_PKCS, 35);

        }

    }

    public static final class SHA256 extends NativeRSASignature {

        public SHA256() throws NoSuchAlgorithmException {

            super(UcryptoMech.CRYPTO_SHA256_RSA_PKCS, 51);

        }

    }

    public static final class SHA384 extends NativeRSASignature {

        public SHA384() throws NoSuchAlgorithmException {

            super(UcryptoMech.CRYPTO_SHA384_RSA_PKCS, 67);

        }

    }

    public static final class SHA512 extends NativeRSASignature {

        public SHA512() throws NoSuchAlgorithmException {

            super(UcryptoMech.CRYPTO_SHA512_RSA_PKCS, 83);

        }

    }

    // internal class for native resource cleanup

    private static class SignatureContextRef extends PhantomReference<NativeRSASignature>

        implements Comparable<SignatureContextRef> {

        private static ReferenceQueue<NativeRSASignature> refQueue =

            new ReferenceQueue<NativeRSASignature>();

        // Needed to keep these references from being GC'ed until when their

        // referents are GC'ed so we can do post-mortem processing

        private static Set<SignatureContextRef> refList =

            new ConcurrentSkipListSet<SignatureContextRef>();

        //           Collections.synchronizedSortedSet(new TreeSet<SignatureContextRef>());

        private final long id;

        private final boolean sign;

        private static void drainRefQueueBounded() {

            while (true) {

                SignatureContextRef next = (SignatureContextRef) refQueue.poll();

                if (next == null) break;

                next.dispose(true);

            }

        }

        SignatureContextRef(NativeRSASignature ns, long id, boolean sign) {

            super(ns, refQueue);

            this.id = id;

            this.sign = sign;

            refList.add(this);

            UcryptoProvider.debug("Resource: track Signature Ctxt " + this.id);

            drainRefQueueBounded();

        }

        public int compareTo(SignatureContextRef other) {

            if (this.id == other.id) {

                return 0;

            } else {

                return (this.id < other.id) ? -1 : 1;

            }

        }

        void dispose(boolean doCancel) {

            refList.remove(this);

            try {

                if (doCancel) {

                    UcryptoProvider.debug("Resource: free Signature Ctxt " + this.id);

                    NativeRSASignature.nativeFinal(id, sign, null, 0, 0);

                } else {

                    UcryptoProvider.debug("Resource: stop tracking Signature Ctxt " + this.id);

                }

            } finally {

                this.clear();

            }

        }

    }

    NativeRSASignature(UcryptoMech mech, int encodedLen)

        throws NoSuchAlgorithmException {

        this.mech = mech;

        this.encodedLen = encodedLen;

        this.keyFactory = new NativeRSAKeyFactory();

    }

    // deprecated but abstract

    @SuppressWarnings("deprecation")

    protected Object engineGetParameter(String param) throws InvalidParameterException {

        throw new UnsupportedOperationException("getParameter() not supported");

    }

    @Override

    protected synchronized void engineInitSign(PrivateKey privateKey)

            throws InvalidKeyException {

        if (privateKey == null) {

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

        }

        NativeKey newKey = key;

        int newSigLength = sigLength;

        // Need to check RSA key length whenever a new private key is set

        if (privateKey != key) {

            if (privateKey instanceof RSAPrivateCrtKey) {

                RSAPrivateCrtKey rsaPrivKey = (RSAPrivateCrtKey) privateKey;

                BigInteger mod = rsaPrivKey.getModulus();

                newSigLength = checkRSAKeyLength(mod);

                try {

                    newKey = (NativeKey) keyFactory.engineGeneratePrivate

                        (new RSAPrivateCrtKeySpec(mod,

                                                  rsaPrivKey.getPublicExponent(),

                                                  rsaPrivKey.getPrivateExponent(),

                                                  rsaPrivKey.getPrimeP(),

                                                  rsaPrivKey.getPrimeQ(),

                                                  rsaPrivKey.getPrimeExponentP(),

                                                  rsaPrivKey.getPrimeExponentQ(),

                                                  rsaPrivKey.getCrtCoefficient()));

                } catch (InvalidKeySpecException ikse) {

                    throw new InvalidKeyException(ikse);

                }

            } else {

                throw new InvalidKeyException("RSAPrivateCrtKey required");

            }

        }

        init(true, newKey, newSigLength);

    }

    @Override

    protected synchronized void engineInitVerify(PublicKey publicKey)

            throws InvalidKeyException {

        if (publicKey == null) {

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

        }

        NativeKey newKey = key;

        int newSigLength = sigLength;

        // Need to check RSA key length whenever a new public key is set

        if (publicKey != key) {

            if (publicKey instanceof RSAPublicKey) {

                BigInteger mod = ((RSAPublicKey) publicKey).getModulus();

                newSigLength = checkRSAKeyLength(mod);

                try {

                    newKey = (NativeKey) keyFactory.engineGeneratePublic

                        (new RSAPublicKeySpec(mod, ((RSAPublicKey) publicKey).getPublicExponent()));

                } catch (InvalidKeySpecException ikse) {

                    throw new InvalidKeyException(ikse);

                }

            } else {

                throw new InvalidKeyException("RSAPublicKey required");

            }

        }

        init(false, newKey, newSigLength);

    }

    // deprecated but abstract

    @SuppressWarnings("deprecation")

    protected void engineSetParameter(String param, Object value) throws InvalidParameterException {

        throw new UnsupportedOperationException("setParameter() not supported");

    }

    @Override

    protected synchronized byte[] engineSign() throws SignatureException {

        byte[] sig = new byte[sigLength];

        int rv = doFinal(sig, 0, sigLength);

        if (rv < 0) {

            throw new SignatureException(new UcryptoException(-rv));

        }

        return sig;

    }

    @Override

    protected synchronized int engineSign(byte[] outbuf, int offset, int len)

        throws SignatureException {

        if (outbuf == null || (offset < 0) || (outbuf.length < (offset + sigLength))

            || (len < sigLength)) {

            throw new SignatureException("Invalid output buffer");

        }

        int rv = doFinal(outbuf, offset, sigLength);

        if (rv < 0) {

            throw new SignatureException(new UcryptoException(-rv));

        }

        return sigLength;

    }

    @Override

    protected synchronized void engineUpdate(byte b) throws SignatureException {

        byte[] in = { b };

        int rv = update(in, 0, 1);

        if (rv < 0) {

            throw new SignatureException(new UcryptoException(-rv));

        }

    }

    @Override

    protected synchronized void engineUpdate(byte[] in, int inOfs, int inLen)

            throws SignatureException {

        if (in == null || inOfs < 0 || inLen == 0) return;

        int rv = update(in, inOfs, inLen);

        if (rv < 0) {

            throw new SignatureException(new UcryptoException(-rv));

        }

    }

    @Override

    protected synchronized void engineUpdate(ByteBuffer in) {

        if (in == null || in.remaining() == 0) return;

        if (in instanceof DirectBuffer == false) {

            // cannot do better than default impl

            super.engineUpdate(in);

            return;

        }

        long inAddr = ((DirectBuffer)in).address();

        int inOfs = in.position();

        int inLen = in.remaining();

        int rv = update((inAddr + inOfs), inLen);

        if (rv < 0) {

            throw new UcryptoException(-rv);

        }

        in.position(inOfs + inLen);

    }

    @Override

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

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

    }

    @Override

    protected synchronized boolean engineVerify(byte[] sigBytes, int sigOfs, int sigLen)

        throws SignatureException {

        if (sigBytes == null || (sigOfs < 0) || (sigBytes.length < (sigOfs + this.sigLength))

            || (sigLen < this.sigLength)) {

            throw new SignatureException("Invalid signature buffer");

        }

        int rv = doFinal(sigBytes, sigOfs, sigLen);

        if (rv == 0) {

            return true;

        } else {

            UcryptoProvider.debug("Signature: " + mech + " verification error " +

                             new UcryptoException(-rv).getMessage());

            return false;

        }

    }

    void reset(boolean doCancel) {

        initialized = false;

        if (pCtxt != null) {

            pCtxt.dispose(doCancel);

            pCtxt = null;

        }

    }

    /**

     * calls ucrypto_sign_init(...) or ucrypto_verify_init(...)

     * @return pointer to the context

     */

    private native static long nativeInit(int mech, boolean sign,

                                          long keyValue, int keyLength);

    /**

     * calls ucrypto_sign_update(...) or ucrypto_verify_update(...)

     * @return an error status code (0 means SUCCESS)

     */

    private native static int nativeUpdate(long pContext, boolean sign,

                                           byte[] in, int inOfs, int inLen);

    /**

     * calls ucrypto_sign_update(...) or ucrypto_verify_update(...)

     * @return an error status code (0 means SUCCESS)

     */

    private native static int nativeUpdate(long pContext, boolean sign,

                                           long pIn, int inLen);

    /**

     * calls ucrypto_sign_final(...) or ucrypto_verify_final(...)

     * @return the length of signature bytes or verification status.

     * If negative, it indicates an error status code

     */

    private native static int nativeFinal(long pContext, boolean sign,

                                          byte[] sig, int sigOfs, int sigLen);

    // actual init() implementation - caller should clone key if needed

    private void init(boolean sign, NativeKey key, int sigLength) {

        reset(true);

        this.sign = sign;

        this.sigLength = sigLength;

        this.key = key;

        long pCtxtVal = nativeInit(mech.value(), sign, key.value(),

                                   key.length());

        initialized = (pCtxtVal != 0L);

        if (initialized) {

            pCtxt = new SignatureContextRef(this, pCtxtVal, sign);

        } else {

            throw new UcryptoException("Cannot initialize Signature");

        }

    }

    private void ensureInitialized() {

        if (!initialized) {

            init(sign, key, sigLength);

            if (!initialized) {

                throw new UcryptoException("Cannot initialize Signature");

            }

        }

    }

    // returns 0 (success) or negative (ucrypto error occurred)

    private int update(byte[] in, int inOfs, int inLen) {

        if (inOfs < 0 || inOfs + inLen > in.length) {

            throw new ArrayIndexOutOfBoundsException();

        }

        ensureInitialized();

        int k = nativeUpdate(pCtxt.id, sign, in, inOfs, inLen);

        if (k < 0) {

            reset(false);

        }

        return k;

    }

    // returns 0 (success) or negative (ucrypto error occurred)

    private int update(long pIn, int inLen) {

        ensureInitialized();

        int k = nativeUpdate(pCtxt.id, sign, pIn, inLen);

        if (k < 0) {

            reset(false);

        }

        return k;

    }

    // returns 0 (success) or negative (ucrypto error occurred)

    private int doFinal(byte[] sigBytes, int sigOfs, int sigLen) {

        try {

            ensureInitialized();

            int k = nativeFinal(pCtxt.id, sign, sigBytes, sigOfs, sigLen);

            return k;

        } finally {

            reset(false);

        }

    }

    // check and return RSA key size in number of bytes

    private int checkRSAKeyLength(BigInteger mod) throws InvalidKeyException {

        int keySize = (mod.bitLength() + 7) >> 3;

        int maxDataSize = keySize - PKCS1PADDING_LEN;

        if (maxDataSize < encodedLen) {

            throw new InvalidKeyException

                ("Key is too short for this signature algorithm");

        }

        return keySize;

    }

}