/*
 * Copyright (c) 2003, 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
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package com.sun.crypto.provider;

import java.util.Locale;

import java.security.*;
import java.security.interfaces.*;
import java.security.spec.AlgorithmParameterSpec;
import java.security.spec.InvalidParameterSpecException;
import java.security.spec.MGF1ParameterSpec;

import javax.crypto.*;
import javax.crypto.spec.PSource;
import javax.crypto.spec.OAEPParameterSpec;

import sun.security.rsa.*;
import sun.security.jca.Providers;
import sun.security.internal.spec.TlsRsaPremasterSecretParameterSpec;
import sun.security.util.KeyUtil;

RSA cipher implementation. Supports RSA en/decryption and signing/verifying
using PKCS#1 v1.5 padding and without padding (raw RSA). Note that raw RSA
is supported mostly for completeness and should only be used in rare cases.
Objects should be instantiated by calling Cipher.getInstance() using the
following algorithm names:
 . "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
 . "RSA/ECB/NoPadding" for rsa RSA.
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
Since:
  1.5/**
 * RSA cipher implementation. Supports RSA en/decryption and signing/verifying
 * using PKCS#1 v1.5 padding and without padding (raw RSA). Note that raw RSA
 * is supported mostly for completeness and should only be used in rare cases.
 *
 * Objects should be instantiated by calling Cipher.getInstance() using the
 * following algorithm names:
 *  . "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
 *  . "RSA/ECB/NoPadding" for rsa RSA.
 *
 * 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   1.5
 * @author  Andreas Sterbenz
 */
public final class RSACipher extends CipherSpi {

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

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

    // constant for raw RSA
    private static final String PAD_NONE  = "NoPadding";
    // constant for PKCS#1 v1.5 RSA
    private static final String PAD_PKCS1 = "PKCS1Padding";
    // constant for PKCS#2 v2.0 OAEP with MGF1
    private static final String PAD_OAEP_MGF1  = "OAEP";

    // 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;

    // padding object
    private RSAPadding padding;

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

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

    // size of the output
    private int outputSize;

    // the public key, if we were initialized using a public key
    private RSAPublicKey publicKey;
    // the private key, if we were initialized using a private key
    private RSAPrivateKey privateKey;

    // hash algorithm for OAEP
    private String oaepHashAlgorithm = "SHA-1";

    // 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_NONE)) {
            paddingType = PAD_NONE;
        } else if (paddingName.equalsIgnoreCase(PAD_PKCS1)) {
            paddingType = PAD_PKCS1;
        } else {
            String lowerPadding = paddingName.toLowerCase(Locale.ENGLISH);
            if (lowerPadding.equals("oaeppadding")) {
                paddingType = PAD_OAEP_MGF1;
            } else if (lowerPadding.startsWith("oaepwith") &&
                       lowerPadding.endsWith("andmgf1padding")) {
                paddingType = PAD_OAEP_MGF1;
                // "oaepwith".length() == 8
                // "andmgf1padding".length() == 14
                oaepHashAlgorithm =
                        paddingName.substring(8, paddingName.length() - 14);
                // check if MessageDigest appears to be available
                // avoid getInstance() call here
                if (Providers.getProviderList().getService
                        ("MessageDigest", oaepHashAlgorithm) == null) {
                    throw new NoSuchPaddingException
                        ("MessageDigest not available for " + paddingName);
                }
            } 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;
    }

    // see JCE spec
    protected AlgorithmParameters engineGetParameters() {
        if (spec != null && spec instanceof OAEPParameterSpec) {
            try {
                AlgorithmParameters params =
                    AlgorithmParameters.getInstance("OAEP",
                        SunJCE.getInstance());
                params.init(spec);
                return params;
            } catch (NoSuchAlgorithmException nsae) {
                // should never happen
                throw new RuntimeException("Cannot find OAEP " +
                    " AlgorithmParameters implementation in SunJCE provider");
            } catch (InvalidParameterSpecException ipse) {
                // should never happen
                throw new RuntimeException("OAEPParameterSpec not supported");
            }
        } else {
            return null;
        }
    }

    // see JCE spec
    protected void engineInit(int opmode, Key key, SecureRandom random)
            throws InvalidKeyException {
        try {
            init(opmode, key, random, null);
        } catch (InvalidAlgorithmParameterException iape) {
            // never thrown when null parameters are used;
            // but re-throw it just in case
            InvalidKeyException ike =
                new InvalidKeyException("Wrong parameters");
            ike.initCause(iape);
            throw ike;
        }
    }

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

    // see JCE spec
    protected void engineInit(int opmode, Key key,
            AlgorithmParameters params, SecureRandom random)
            throws InvalidKeyException, InvalidAlgorithmParameterException {
        if (params == null) {
            init(opmode, key, random, null);
        } else {
            try {
                OAEPParameterSpec spec =
                        params.getParameterSpec(OAEPParameterSpec.class);
                init(opmode, key, random, spec);
            } catch (InvalidParameterSpecException ipse) {
                InvalidAlgorithmParameterException iape =
                    new InvalidAlgorithmParameterException("Wrong parameter");
                iape.initCause(ipse);
                throw iape;
            }
        }
    }

    // initialize this cipher
    @SuppressWarnings("deprecation")
    private void init(int opmode, Key key, SecureRandom random,
            AlgorithmParameterSpec params)
            throws InvalidKeyException, InvalidAlgorithmParameterException {
        boolean encrypt;
        switch (opmode) {
        case Cipher.ENCRYPT_MODE:
        case Cipher.WRAP_MODE:
            encrypt = true;
            break;
        case Cipher.DECRYPT_MODE:
        case Cipher.UNWRAP_MODE:
            encrypt = false;
            break;
        default:
            throw new InvalidKeyException("Unknown mode: " + opmode);
        }
        RSAKey rsaKey = RSAKeyFactory.toRSAKey(key);
        if (key instanceof RSAPublicKey) {
            mode = encrypt ? MODE_ENCRYPT : MODE_VERIFY;
            publicKey = (RSAPublicKey)key;
            privateKey = null;
        } else { // must be RSAPrivateKey per check in toRSAKey
            mode = encrypt ? MODE_SIGN : MODE_DECRYPT;
            privateKey = (RSAPrivateKey)key;
            publicKey = null;
        }
        int n = RSACore.getByteLength(rsaKey.getModulus());
        outputSize = n;
        bufOfs = 0;
        if (paddingType == PAD_NONE) {
            if (params != null) {
                throw new InvalidAlgorithmParameterException
                ("Parameters not supported");
            }
            padding = RSAPadding.getInstance(RSAPadding.PAD_NONE, n, random);
            buffer = new byte[n];
        } else if (paddingType == PAD_PKCS1) {
            if (params != null) {
                if (!(params instanceof TlsRsaPremasterSecretParameterSpec)) {
                    throw new InvalidAlgorithmParameterException(
                            "Parameters not supported");
                }

                spec = params;
                this.random = random;   // for TLS RSA premaster secret
            }
            int blockType = (mode <= MODE_DECRYPT) ? RSAPadding.PAD_BLOCKTYPE_2
                                                   : RSAPadding.PAD_BLOCKTYPE_1;
            padding = RSAPadding.getInstance(blockType, n, random);
            if (encrypt) {
                int k = padding.getMaxDataSize();
                buffer = new byte[k];
            } else {
                buffer = new byte[n];
            }
        } else { // PAD_OAEP_MGF1
            if ((mode == MODE_SIGN) || (mode == MODE_VERIFY)) {
                throw new InvalidKeyException
                        ("OAEP cannot be used to sign or verify signatures");
            }
            if (params != null) {
                if (!(params instanceof OAEPParameterSpec)) {
                    throw new InvalidAlgorithmParameterException
                        ("Wrong Parameters for OAEP Padding");
                }
                spec = params;
            } else {
                spec = new OAEPParameterSpec(oaepHashAlgorithm, "MGF1",
                    MGF1ParameterSpec.SHA1, PSource.PSpecified.DEFAULT);
            }
            padding = RSAPadding.getInstance(RSAPadding.PAD_OAEP_MGF1, n,
                random, (OAEPParameterSpec)spec);
            if (encrypt) {
                int k = padding.getMaxDataSize();
                buffer = new byte[k];
            } else {
                buffer = new byte[n];
            }
        }
    }

    // internal update method
    private void update(byte[] in, int inOfs, int inLen) {
        if ((inLen == 0) || (in == null)) {
            return;
        }
        if (bufOfs + inLen > buffer.length) {
            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 + " bytes");
        }
        try {
            byte[] data;
            switch (mode) {
            case MODE_SIGN:
                data = padding.pad(buffer, 0, bufOfs);
                return RSACore.rsa(data, privateKey, true);
            case MODE_VERIFY:
                byte[] verifyBuffer = RSACore.convert(buffer, 0, bufOfs);
                data = RSACore.rsa(verifyBuffer, publicKey);
                return padding.unpad(data);
            case MODE_ENCRYPT:
                data = padding.pad(buffer, 0, bufOfs);
                return RSACore.rsa(data, publicKey);
            case MODE_DECRYPT:
                byte[] decryptBuffer = RSACore.convert(buffer, 0, bufOfs);
                data = RSACore.rsa(decryptBuffer, privateKey, false);
                return padding.unpad(data);
            default:
                throw new AssertionError("Internal error");
            }
        } 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();
        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
    @SuppressWarnings("deprecation")
    protected 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 ConstructKeys.constructKey(encoded, algorithm, type);
    }

    // see JCE spec
    protected int engineGetKeySize(Key key) throws InvalidKeyException {
        RSAKey rsaKey = RSAKeyFactory.toRSAKey(key);
        return rsaKey.getModulus().bitLength();
    }
}