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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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package sun.security.mscapi;

import java.math.BigInteger;
import java.security.*;
import java.security.Key;
import java.security.interfaces.*;
import java.security.spec.*;

import javax.crypto.*;
import javax.crypto.spec.*;

import sun.security.rsa.RSAKeyFactory;
import sun.security.internal.spec.TlsRsaPremasterSecretParameterSpec;
import sun.security.util.KeyUtil;

RSA cipher implementation using the Microsoft Crypto API.
Supports RSA en/decryption and signing/verifying using PKCS#1 v1.5 padding.
Objects should be instantiated by calling Cipher.getInstance() using the
following algorithm name:
 . "RSA/ECB/PKCS1Padding" (or "RSA") for PKCS#1 padding. The mode (blocktype)
   is selected based on the en/decryption mode and public/private key used.
We only do one RSA operation per doFinal() call. If the application passes
more data via calls to update() or doFinal(), we throw an
IllegalBlockSizeException when doFinal() is called (see JCE API spec).
Bulk encryption using RSA does not make sense and is not standardized.
Note: RSA keys should be at least 512 bits long
Author:
 Andreas Sterbenz,  Vincent Ryan
Since:
  1.6/**
 * RSA cipher implementation using the Microsoft Crypto API.
 * Supports RSA en/decryption and signing/verifying using PKCS#1 v1.5 padding.
 *
 * Objects should be instantiated by calling Cipher.getInstance() using the
 * following algorithm name:
 *
 *  . "RSA/ECB/PKCS1Padding" (or "RSA") for PKCS#1 padding. The mode (blocktype)
 *    is selected based on the en/decryption mode and public/private key used.
 *
 * We only do one RSA operation per doFinal() call. If the application passes
 * more data via calls to update() or doFinal(), we throw an
 * IllegalBlockSizeException when doFinal() is called (see JCE API spec).
 * Bulk encryption using RSA does not make sense and is not standardized.
 *
 * Note: RSA keys should be at least 512 bits long
 *
 * @since   1.6
 * @author  Andreas Sterbenz
 * @author  Vincent Ryan
 */
public final class RSACipher extends CipherSpi {

    // constant for an empty byte array
    private final static byte[] B0 = new byte[0];

    // mode constant for public key encryption
    private final static int MODE_ENCRYPT = 1;
    // mode constant for private key decryption
    private final static int MODE_DECRYPT = 2;
    // mode constant for private key encryption (signing)
    private final static int MODE_SIGN    = 3;
    // mode constant for public key decryption (verifying)
    private final static int MODE_VERIFY  = 4;

    // constant for PKCS#1 v1.5 RSA
    private final static String PAD_PKCS1 = "PKCS1Padding";
    private final static int PAD_PKCS1_LENGTH = 11;

    // current mode, one of MODE_* above. Set when init() is called
    private int mode;

    // active padding type, one of PAD_* above. Set by setPadding()
    private String paddingType;
    private int paddingLength = 0;

    // buffer for the data
    private byte[] buffer;
    // offset into the buffer (number of bytes buffered)
    private int bufOfs;

    // size of the output (the length of the key).
    private int outputSize;

    // the public key, if we were initialized using a public key
    private sun.security.mscapi.Key publicKey;

    // the private key, if we were initialized using a private key
    private sun.security.mscapi.Key privateKey;

    // cipher parameter for TLS RSA premaster secret
    private AlgorithmParameterSpec spec = null;

    // the source of randomness
    private SecureRandom random;

    public RSACipher() {
        paddingType = PAD_PKCS1;
    }

    // modes do not make sense for RSA, but allow ECB
    // see JCE spec
    protected void engineSetMode(String mode) throws NoSuchAlgorithmException {
        if (mode.equalsIgnoreCase("ECB") == false) {
            throw new NoSuchAlgorithmException("Unsupported mode " + mode);
        }
    }

    // set the padding type
    // see JCE spec
    protected void engineSetPadding(String paddingName)
            throws NoSuchPaddingException {
        if (paddingName.equalsIgnoreCase(PAD_PKCS1)) {
            paddingType = PAD_PKCS1;
        } else {
            throw new NoSuchPaddingException
                ("Padding " + paddingName + " not supported");
        }
    }

    // return 0 as block size, we are not a block cipher
    // see JCE spec
    protected int engineGetBlockSize() {
        return 0;
    }

    // return the output size
    // see JCE spec
    protected int engineGetOutputSize(int inputLen) {
        return outputSize;
    }

    // no iv, return null
    // see JCE spec
    protected byte[] engineGetIV() {
        return null;
    }

    // no parameters, return null
    // see JCE spec
    protected AlgorithmParameters engineGetParameters() {
        return null;
    }

    // see JCE spec
    protected void engineInit(int opmode, Key key, SecureRandom random)
            throws InvalidKeyException {
        init(opmode, key);
    }

    // see JCE spec
    protected void engineInit(int opmode, Key key,
            AlgorithmParameterSpec params, SecureRandom random)
            throws InvalidKeyException, InvalidAlgorithmParameterException {

        if (params != null) {
            if (!(params instanceof TlsRsaPremasterSecretParameterSpec)) {
                throw new InvalidAlgorithmParameterException(
                        "Parameters not supported");
            }
            spec = params;
            this.random = random;   // for TLS RSA premaster secret
        }
        init(opmode, key);
    }

    // see JCE spec
    protected void engineInit(int opmode, Key key,
            AlgorithmParameters params, SecureRandom random)
            throws InvalidKeyException, InvalidAlgorithmParameterException {

        if (params != null) {
            throw new InvalidAlgorithmParameterException
                ("Parameters not supported");
        }
        init(opmode, key);
    }

    // initialize this cipher
    private void init(int opmode, Key key) throws InvalidKeyException {

        boolean encrypt;

        switch (opmode) {
        case Cipher.ENCRYPT_MODE:
        case Cipher.WRAP_MODE:
            paddingLength = PAD_PKCS1_LENGTH;
            encrypt = true;
            break;
        case Cipher.DECRYPT_MODE:
        case Cipher.UNWRAP_MODE:
            paddingLength = 0; // reset
            encrypt = false;
            break;
        default:
            throw new InvalidKeyException("Unknown mode: " + opmode);
        }

        if (!(key instanceof sun.security.mscapi.Key)) {
            if (key instanceof java.security.interfaces.RSAPublicKey) {
                java.security.interfaces.RSAPublicKey rsaKey =
                    (java.security.interfaces.RSAPublicKey) key;

                // 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 = RSASignature.generatePublicKeyBlob(
                    keyBitLength, modulusBytes, exponentBytes);

                try {
                    key = RSASignature.importPublicKey(keyBlob, keyBitLength);

                } catch (KeyStoreException e) {
                    throw new InvalidKeyException(e);
                }

            } else {
                throw new InvalidKeyException("Unsupported key type: " + key);
            }
        }

        if (key instanceof PublicKey) {
            mode = encrypt ? MODE_ENCRYPT : MODE_VERIFY;
            publicKey = (sun.security.mscapi.Key)key;
            privateKey = null;
            outputSize = publicKey.length() / 8;
        } else if (key instanceof PrivateKey) {
            mode = encrypt ? MODE_SIGN : MODE_DECRYPT;
            privateKey = (sun.security.mscapi.Key)key;
            publicKey = null;
            outputSize = privateKey.length() / 8;
        } else {
            throw new InvalidKeyException("Unknown key type: " + key);
        }

        bufOfs = 0;
        buffer = new byte[outputSize];
    }

    // internal update method
    private void update(byte[] in, int inOfs, int inLen) {
        if ((inLen == 0) || (in == null)) {
            return;
        }
        if (bufOfs + inLen > (buffer.length - paddingLength)) {
            bufOfs = buffer.length + 1;
            return;
        }
        System.arraycopy(in, inOfs, buffer, bufOfs, inLen);
        bufOfs += inLen;
    }

    // internal doFinal() method. Here we perform the actual RSA operation
    private byte[] doFinal() throws BadPaddingException,
            IllegalBlockSizeException {
        if (bufOfs > buffer.length) {
            throw new IllegalBlockSizeException("Data must not be longer "
                + "than " + (buffer.length - paddingLength)  + " bytes");
        }

        try {
            byte[] data = buffer;
            switch (mode) {
            case MODE_SIGN:
                return encryptDecrypt(data, bufOfs,
                    privateKey.getHCryptKey(), true);

            case MODE_VERIFY:
                return encryptDecrypt(data, bufOfs,
                    publicKey.getHCryptKey(), false);

            case MODE_ENCRYPT:
                return encryptDecrypt(data, bufOfs,
                    publicKey.getHCryptKey(), true);

            case MODE_DECRYPT:
                return encryptDecrypt(data, bufOfs,
                    privateKey.getHCryptKey(), false);

            default:
                throw new AssertionError("Internal error");
            }

        } catch (KeyException e) {
            throw new ProviderException(e);

        } finally {
            bufOfs = 0;
        }
    }

    // see JCE spec
    protected byte[] engineUpdate(byte[] in, int inOfs, int inLen) {
        update(in, inOfs, inLen);
        return B0;
    }

    // see JCE spec
    protected int engineUpdate(byte[] in, int inOfs, int inLen, byte[] out,
            int outOfs) {
        update(in, inOfs, inLen);
        return 0;
    }

    // see JCE spec
    protected byte[] engineDoFinal(byte[] in, int inOfs, int inLen)
            throws BadPaddingException, IllegalBlockSizeException {
        update(in, inOfs, inLen);
        return doFinal();
    }

    // see JCE spec
    protected int engineDoFinal(byte[] in, int inOfs, int inLen, byte[] out,
            int outOfs) throws ShortBufferException, BadPaddingException,
            IllegalBlockSizeException {
        if (outputSize > out.length - outOfs) {
            throw new ShortBufferException
                ("Need " + outputSize + " bytes for output");
        }
        update(in, inOfs, inLen);
        byte[] result = doFinal();
        int n = result.length;
        System.arraycopy(result, 0, out, outOfs, n);
        return n;
    }

    // see JCE spec
    protected byte[] engineWrap(Key key) throws InvalidKeyException,
            IllegalBlockSizeException {
        byte[] encoded = key.getEncoded(); // TODO - unextractable key
        if ((encoded == null) || (encoded.length == 0)) {
            throw new InvalidKeyException("Could not obtain encoded key");
        }
        if (encoded.length > buffer.length) {
            throw new InvalidKeyException("Key is too long for wrapping");
        }
        update(encoded, 0, encoded.length);
        try {
            return doFinal();
        } catch (BadPaddingException e) {
            // should not occur
            throw new InvalidKeyException("Wrapping failed", e);
        }
    }

    // see JCE spec
    protected java.security.Key engineUnwrap(byte[] wrappedKey,
            String algorithm,
            int type) throws InvalidKeyException, NoSuchAlgorithmException {

        if (wrappedKey.length > buffer.length) {
            throw new InvalidKeyException("Key is too long for unwrapping");
        }

        boolean isTlsRsaPremasterSecret =
                algorithm.equals("TlsRsaPremasterSecret");
        Exception failover = null;
        byte[] encoded = null;

        update(wrappedKey, 0, wrappedKey.length);
        try {
            encoded = doFinal();
        } catch (BadPaddingException e) {
            if (isTlsRsaPremasterSecret) {
                failover = e;
            } else {
                throw new InvalidKeyException("Unwrapping failed", e);
            }
        } catch (IllegalBlockSizeException e) {
            // should not occur, handled with length check above
            throw new InvalidKeyException("Unwrapping failed", e);
        }

        if (isTlsRsaPremasterSecret) {
            if (!(spec instanceof TlsRsaPremasterSecretParameterSpec)) {
                throw new IllegalStateException(
                        "No TlsRsaPremasterSecretParameterSpec specified");
            }

            // polish the TLS premaster secret
            encoded = KeyUtil.checkTlsPreMasterSecretKey(
                ((TlsRsaPremasterSecretParameterSpec)spec).getClientVersion(),
                ((TlsRsaPremasterSecretParameterSpec)spec).getServerVersion(),
                random, encoded, (failover != null));
        }

        return constructKey(encoded, algorithm, type);
    }

    // see JCE spec
    protected int engineGetKeySize(Key key) throws InvalidKeyException {

        if (key instanceof sun.security.mscapi.Key) {
            return ((sun.security.mscapi.Key) key).length();

        } else if (key instanceof RSAKey) {
            return ((RSAKey) key).getModulus().bitLength();

        } else {
            throw new InvalidKeyException("Unsupported key type: " + key);
        }
    }

    // Construct an X.509 encoded public key.
    private static PublicKey constructPublicKey(byte[] encodedKey,
        String encodedKeyAlgorithm)
            throws InvalidKeyException, NoSuchAlgorithmException {

        try {
            KeyFactory keyFactory = KeyFactory.getInstance(encodedKeyAlgorithm);
            X509EncodedKeySpec keySpec = new X509EncodedKeySpec(encodedKey);

            return keyFactory.generatePublic(keySpec);

        } catch (NoSuchAlgorithmException nsae) {
            throw new NoSuchAlgorithmException("No installed provider " +
                "supports the " + encodedKeyAlgorithm + " algorithm", nsae);

        } catch (InvalidKeySpecException ike) {
            throw new InvalidKeyException("Cannot construct public key", ike);
        }
    }

    // Construct a PKCS #8 encoded private key.
    private static PrivateKey constructPrivateKey(byte[] encodedKey,
        String encodedKeyAlgorithm)
            throws InvalidKeyException, NoSuchAlgorithmException {

        try {
            KeyFactory keyFactory = KeyFactory.getInstance(encodedKeyAlgorithm);
            PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(encodedKey);

            return keyFactory.generatePrivate(keySpec);

        } catch (NoSuchAlgorithmException nsae) {
            throw new NoSuchAlgorithmException("No installed provider " +
                "supports the " + encodedKeyAlgorithm + " algorithm", nsae);

        } catch (InvalidKeySpecException ike) {
            throw new InvalidKeyException("Cannot construct private key", ike);
        }
    }

    // Construct an encoded secret key.
    private static SecretKey constructSecretKey(byte[] encodedKey,
        String encodedKeyAlgorithm) {

        return new SecretKeySpec(encodedKey, encodedKeyAlgorithm);
    }

    private static Key constructKey(byte[] encodedKey,
            String encodedKeyAlgorithm,
            int keyType) throws InvalidKeyException, NoSuchAlgorithmException {

        switch (keyType) {
            case Cipher.PUBLIC_KEY:
                return constructPublicKey(encodedKey, encodedKeyAlgorithm);
            case Cipher.PRIVATE_KEY:
                return constructPrivateKey(encodedKey, encodedKeyAlgorithm);
            case Cipher.SECRET_KEY:
                return constructSecretKey(encodedKey, encodedKeyAlgorithm);
            default:
                throw new InvalidKeyException("Unknown key type " + keyType);
        }
    }

    /*
     * Encrypt/decrypt a data buffer using Microsoft Crypto API with HCRYPTKEY.
     * It expects and returns ciphertext data in big-endian form.
     */
    private native static byte[] encryptDecrypt(byte[] data, int dataSize,
        long hCryptKey, boolean doEncrypt) throws KeyException;

}