/*

 * Copyright (c) 2005, 2012, 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.mscapi;

import java.nio.ByteBuffer;

import java.security.PublicKey;

import java.security.PrivateKey;

import java.security.InvalidKeyException;

import java.security.InvalidParameterException;

import java.security.KeyStoreException;

import java.security.NoSuchAlgorithmException;

import java.security.ProviderException;

import java.security.MessageDigest;

import java.security.SignatureException;

import java.math.BigInteger;

import sun.security.rsa.RSAKeyFactory;

/**

 * RSA signature implementation. Supports RSA signing using PKCS#1 v1.5 padding.

 *

 * Objects should be instantiated by calling Signature.getInstance() using the

 * following algorithm names:

 *

 *  . "NONEwithRSA"

 *  . "SHA1withRSA"

 *  . "SHA256withRSA"

 *  . "SHA384withRSA"

 *  . "SHA512withRSA"

 *  . "MD5withRSA"

 *  . "MD2withRSA"

 *

 * NOTE: RSA keys must be at least 512 bits long.

 *

 * NOTE: NONEwithRSA must be supplied with a pre-computed message digest.

 *       Only the following digest algorithms are supported: MD5, SHA-1,

 *       SHA-256, SHA-384, SHA-512 and a special-purpose digest

 *       algorithm which is a concatenation of SHA-1 and MD5 digests.

 *

 * @since   1.6

 * @author  Stanley Man-Kit Ho

 */

abstract class RSASignature extends java.security.SignatureSpi

{

    // message digest implementation we use

    private final MessageDigest messageDigest;

    // message digest name

    private String messageDigestAlgorithm;

    // flag indicating whether the digest has been reset

    private boolean needsReset;

    // the signing key

    private Key privateKey = null;

    // the verification key

    private Key publicKey = null;

    /**

     * Constructs a new RSASignature. Used by Raw subclass.

     */

    RSASignature() {

        messageDigest = null;

        messageDigestAlgorithm = null;

    }

    /**

     * Constructs a new RSASignature. Used by subclasses.

     */

    RSASignature(String digestName) {

        try {

            messageDigest = MessageDigest.getInstance(digestName);

            // Get the digest's canonical name

            messageDigestAlgorithm = messageDigest.getAlgorithm();

        } catch (NoSuchAlgorithmException e) {

           throw new ProviderException(e);

        }

        needsReset = false;

    }

    // Nested class for NONEwithRSA signatures

    public static final class Raw extends RSASignature {

        // the longest supported digest is 512 bits (SHA-512)

        private static final int RAW_RSA_MAX = 64;

        private final byte[] precomputedDigest;

        private int offset = 0;

        public Raw() {

            precomputedDigest = new byte[RAW_RSA_MAX];

        }

        // Stores the precomputed message digest value.

        @Override

        protected void engineUpdate(byte b) throws SignatureException {

            if (offset >= precomputedDigest.length) {

                offset = RAW_RSA_MAX + 1;

                return;

            }

            precomputedDigest[offset++] = b;

        }

        // Stores the precomputed message digest value.

        @Override

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

                throws SignatureException {

            if (offset + len > precomputedDigest.length) {

                offset = RAW_RSA_MAX + 1;

                return;

            }

            System.arraycopy(b, off, precomputedDigest, offset, len);

            offset += len;

        }

        // Stores the precomputed message digest value.

        @Override

        protected void engineUpdate(ByteBuffer byteBuffer) {

            int len = byteBuffer.remaining();

            if (len <= 0) {

                return;

            }

            if (offset + len > precomputedDigest.length) {

                offset = RAW_RSA_MAX + 1;

                return;

            }

            byteBuffer.get(precomputedDigest, offset, len);

            offset += len;

        }

        @Override

        protected void resetDigest(){

            offset = 0;

        }

        // Returns the precomputed message digest value.

        @Override

        protected byte[] getDigestValue() throws SignatureException {

            if (offset > RAW_RSA_MAX) {

                throw new SignatureException("Message digest is too long");

            }

            // Determine the digest algorithm from the digest length

            if (offset == 20) {

                setDigestName("SHA1");

            } else if (offset == 36) {

                setDigestName("SHA1+MD5");

            } else if (offset == 32) {

                setDigestName("SHA-256");

            } else if (offset == 48) {

                setDigestName("SHA-384");

            } else if (offset == 64) {

                setDigestName("SHA-512");

            } else if (offset == 16) {

                setDigestName("MD5");

            } else {

                throw new SignatureException(

                    "Message digest length is not supported");

            }

            byte[] result = new byte[offset];

            System.arraycopy(precomputedDigest, 0, result, 0, offset);

            offset = 0;

            return result;

        }

    }

    public static final class SHA1 extends RSASignature {

        public SHA1() {

            super("SHA1");

        }

    }

    public static final class SHA256 extends RSASignature {

        public SHA256() {

            super("SHA-256");

        }

    }

    public static final class SHA384 extends RSASignature {

        public SHA384() {

            super("SHA-384");

        }

    }

    public static final class SHA512 extends RSASignature {

        public SHA512() {

            super("SHA-512");

        }

    }

    public static final class MD5 extends RSASignature {

        public MD5() {

            super("MD5");

        }

    }

    public static final class MD2 extends RSASignature {

        public MD2() {

            super("MD2");

        }

    }

    // initialize for signing. See JCA doc

    protected void engineInitVerify(PublicKey key)

        throws InvalidKeyException

    {

        // This signature accepts only RSAPublicKey

        if ((key instanceof java.security.interfaces.RSAPublicKey) == false) {

            throw new InvalidKeyException("Key type not supported");

        }

        java.security.interfaces.RSAPublicKey rsaKey =

            (java.security.interfaces.RSAPublicKey) key;

        if ((key instanceof sun.security.mscapi.RSAPublicKey) == false) {

            // convert key to MSCAPI format

            BigInteger modulus = rsaKey.getModulus();

            BigInteger exponent =  rsaKey.getPublicExponent();

            // Check against the local and global values to make sure

            // the sizes are ok.  Round up to the nearest byte.

            RSAKeyFactory.checkKeyLengths(((modulus.bitLength() + 7) & ~7),

                exponent, -1, RSAKeyPairGenerator.KEY_SIZE_MAX);

            byte[] modulusBytes = modulus.toByteArray();

            byte[] exponentBytes = exponent.toByteArray();

            // Adjust key length due to sign bit

            int keyBitLength = (modulusBytes[0] == 0)

                ? (modulusBytes.length - 1) * 8

                : modulusBytes.length * 8;

            byte[] keyBlob = generatePublicKeyBlob(

                keyBitLength, modulusBytes, exponentBytes);

            try {

                publicKey = importPublicKey(keyBlob, keyBitLength);

            } catch (KeyStoreException e) {

                throw new InvalidKeyException(e);

            }

        } else {

            publicKey = (sun.security.mscapi.RSAPublicKey) key;

        }

        this.privateKey = null;

        resetDigest();

    }

    // initialize for signing. See JCA doc

    protected void engineInitSign(PrivateKey key) throws InvalidKeyException

    {

        // This signature accepts only RSAPrivateKey

        if ((key instanceof sun.security.mscapi.RSAPrivateKey) == false) {

            throw new InvalidKeyException("Key type not supported");

        }

        privateKey = (sun.security.mscapi.RSAPrivateKey) key;

        // Check against the local and global values to make sure

        // the sizes are ok.  Round up to nearest byte.

        RSAKeyFactory.checkKeyLengths(((privateKey.length() + 7) & ~7),

            null, RSAKeyPairGenerator.KEY_SIZE_MIN,

            RSAKeyPairGenerator.KEY_SIZE_MAX);

        this.publicKey = null;

        resetDigest();

    }

    /**

     * Resets the message digest if needed.

     */

    protected void resetDigest() {

        if (needsReset) {

            messageDigest.reset();

            needsReset = false;

        }

    }

    protected byte[] getDigestValue() throws SignatureException {

        needsReset = false;

        return messageDigest.digest();

    }

    protected void setDigestName(String name) {

        messageDigestAlgorithm = name;

    }

    /**

     * Updates the data to be signed or verified

     * using the specified byte.

     *

     * @param b the byte to use for the update.

     *

     * @exception SignatureException if the engine is not initialized

     * properly.

     */

    protected void engineUpdate(byte b) throws SignatureException

    {

        messageDigest.update(b);

        needsReset = true;

    }

    /**

     * Updates the data to be signed or verified, using the

     * specified array of bytes, starting at the specified offset.

     *

     * @param b the array of bytes

     * @param off the offset to start from in the array of bytes

     * @param len the number of bytes to use, starting at offset

     *

     * @exception SignatureException if the engine is not initialized

     * properly

     */

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

        throws SignatureException

    {

        messageDigest.update(b, off, len);

        needsReset = true;

    }

    /**

     * Updates the data to be signed or verified, using the

     * specified ByteBuffer.

     *

     * @param input the ByteBuffer

     */

    protected void engineUpdate(ByteBuffer input)

    {

        messageDigest.update(input);

        needsReset = true;

    }

    /**

     * Returns the signature bytes of all the data

     * updated so far.

     * The format of the signature depends on the underlying

     * signature scheme.

     *

     * @return the signature bytes of the signing operation's result.

     *

     * @exception SignatureException if the engine is not

     * initialized properly or if this signature algorithm is unable to

     * process the input data provided.

     */

    protected byte[] engineSign() throws SignatureException {

        byte[] hash = getDigestValue();

        // Omit the hash OID when generating a Raw signature

        boolean noHashOID = this instanceof Raw;

        // Sign hash using MS Crypto APIs

        byte[] result = signHash(noHashOID, hash, hash.length,

            messageDigestAlgorithm, privateKey.getHCryptProvider(),

            privateKey.getHCryptKey());

        // Convert signature array from little endian to big endian

        return convertEndianArray(result);

    }

    /**

     * Convert array from big endian to little endian, or vice versa.

     */

    private byte[] convertEndianArray(byte[] byteArray)

    {

        if (byteArray == null || byteArray.length == 0)

            return byteArray;

        byte [] retval = new byte[byteArray.length];

        // make it big endian

        for (int i=0;i < byteArray.length;i++)

            retval[i] = byteArray[byteArray.length - i - 1];

        return retval;

    }

    /**

     * Sign hash using Microsoft Crypto API with HCRYPTKEY.

     * The returned data is in little-endian.

     */

    private native static byte[] signHash(boolean noHashOID, byte[] hash,

        int hashSize, String hashAlgorithm, long hCryptProv, long hCryptKey)

            throws SignatureException;

    /**

     * Verify a signed hash using Microsoft Crypto API with HCRYPTKEY.

     */

    private native static boolean verifySignedHash(byte[] hash, int hashSize,

        String hashAlgorithm, byte[] signature, int signatureSize,

        long hCryptProv, long hCryptKey) throws SignatureException;

    /**

     * Verifies the passed-in signature.

     *

     * @param sigBytes the signature bytes to be verified.

     *

     * @return true if the signature was verified, false if not.

     *

     * @exception SignatureException if the engine is not

     * initialized properly, the passed-in signature is improperly

     * encoded or of the wrong type, if this signature algorithm is unable to

     * process the input data provided, etc.

     */

    protected boolean engineVerify(byte[] sigBytes)

        throws SignatureException

    {

        byte[] hash = getDigestValue();

        return verifySignedHash(hash, hash.length,

            messageDigestAlgorithm, convertEndianArray(sigBytes),

            sigBytes.length, publicKey.getHCryptProvider(),

            publicKey.getHCryptKey());

    }

    /**

     * Sets the specified algorithm parameter to the specified

     * value. This method supplies a general-purpose mechanism through

     * which it is possible to set the various parameters of this object.

     * A parameter may be any settable parameter for the algorithm, such as

     * a parameter size, or a source of random bits for signature generation

     * (if appropriate), or an indication of whether or not to perform

     * a specific but optional computation. A uniform algorithm-specific

     * naming scheme for each parameter is desirable but left unspecified

     * at this time.

     *

     * @param param the string identifier of the parameter.

     *

     * @param value the parameter value.

     *

     * @exception InvalidParameterException if <code>param</code> is an

     * invalid parameter for this signature algorithm engine,

     * the parameter is already set

     * and cannot be set again, a security exception occurs, and so on.

     *

     * @deprecated Replaced by {@link

     * #engineSetParameter(java.security.spec.AlgorithmParameterSpec)

     * engineSetParameter}.

     */

    @Deprecated

    protected void engineSetParameter(String param, Object value)

        throws InvalidParameterException

    {

        throw new InvalidParameterException("Parameter not supported");

    }

    /**

     * Gets the value of the specified algorithm parameter.

     * This method supplies a general-purpose mechanism through which it

     * is possible to get the various parameters of this object. A parameter

     * may be any settable parameter for the algorithm, such as a parameter

     * size, or  a source of random bits for signature generation (if

     * appropriate), or an indication of whether or not to perform a

     * specific but optional computation. A uniform algorithm-specific

     * naming scheme for each parameter is desirable but left unspecified

     * at this time.

     *

     * @param param the string name of the parameter.

     *

     * @return the object that represents the parameter value, or null if

     * there is none.

     *

     * @exception InvalidParameterException if <code>param</code> is an

     * invalid parameter for this engine, or another exception occurs while

     * trying to get this parameter.

     *

     * @deprecated

     */

    @Deprecated

    protected Object engineGetParameter(String param)

        throws InvalidParameterException

    {

        throw new InvalidParameterException("Parameter not supported");

    }

    /**

     * Generates a public-key BLOB from a key's components.