| /**************************************************************** |
| * Licensed to the Apache Software Foundation (ASF) under one * |
| * or more contributor license agreements. See the NOTICE file * |
| * distributed with this work for additional information * |
| * regarding copyright ownership. The ASF licenses this file * |
| * to you under the Apache License, Version 2.0 (the * |
| * "License"); you may not use this file except in compliance * |
| * with the License. You may obtain a copy of the License at * |
| * * |
| * http://www.apache.org/licenses/LICENSE-2.0 * |
| * * |
| * Unless required by applicable law or agreed to in writing, * |
| * software distributed under the License is distributed on an * |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY * |
| * KIND, either express or implied. See the License for the * |
| * specific language governing permissions and limitations * |
| * under the License. * |
| ****************************************************************/ |
| |
| package org.apache.james.mime4j.storage; |
| |
| import java.io.IOException; |
| import java.io.InputStream; |
| import java.security.GeneralSecurityException; |
| import java.security.NoSuchAlgorithmException; |
| |
| import javax.crypto.Cipher; |
| import javax.crypto.CipherInputStream; |
| import javax.crypto.CipherOutputStream; |
| import javax.crypto.KeyGenerator; |
| import javax.crypto.spec.SecretKeySpec; |
| |
| /** |
| * A {@link StorageProvider} that transparently scrambles and unscrambles the |
| * data stored by another <code>StorageProvider</code>. |
| * |
| * <p> |
| * Example usage: |
| * |
| * <pre> |
| * StorageProvider mistrusted = new TempFileStorageProvider(); |
| * StorageProvider enciphered = new CipherStorageProvider(mistrusted); |
| * StorageProvider provider = new ThresholdStorageProvider(enciphered); |
| * DefaultStorageProvider.setInstance(provider); |
| * </pre> |
| */ |
| public class CipherStorageProvider extends AbstractStorageProvider { |
| |
| private final StorageProvider backend; |
| private final String algorithm; |
| private final KeyGenerator keygen; |
| |
| /** |
| * Creates a new <code>CipherStorageProvider</code> for the given back-end |
| * using the Blowfish cipher algorithm. |
| * |
| * @param backend |
| * back-end storage strategy to encrypt. |
| */ |
| public CipherStorageProvider(StorageProvider backend) { |
| this(backend, "Blowfish"); |
| } |
| |
| /** |
| * Creates a new <code>CipherStorageProvider</code> for the given back-end |
| * and cipher algorithm. |
| * |
| * @param backend |
| * back-end storage strategy to encrypt. |
| * @param algorithm |
| * the name of the symmetric block cipher algorithm such as |
| * "Blowfish", "AES" or "RC2". |
| */ |
| public CipherStorageProvider(StorageProvider backend, String algorithm) { |
| if (backend == null) |
| throw new IllegalArgumentException(); |
| |
| try { |
| this.backend = backend; |
| this.algorithm = algorithm; |
| this.keygen = KeyGenerator.getInstance(algorithm); |
| } catch (NoSuchAlgorithmException e) { |
| throw new IllegalArgumentException(e); |
| } |
| } |
| |
| public StorageOutputStream createStorageOutputStream() throws IOException { |
| SecretKeySpec skeySpec = getSecretKeySpec(); |
| |
| return new CipherStorageOutputStream(backend |
| .createStorageOutputStream(), algorithm, skeySpec); |
| } |
| |
| private SecretKeySpec getSecretKeySpec() { |
| byte[] raw = keygen.generateKey().getEncoded(); |
| return new SecretKeySpec(raw, algorithm); |
| } |
| |
| private static final class CipherStorageOutputStream extends |
| StorageOutputStream { |
| private final StorageOutputStream storageOut; |
| private final String algorithm; |
| private final SecretKeySpec skeySpec; |
| private final CipherOutputStream cipherOut; |
| |
| public CipherStorageOutputStream(StorageOutputStream out, |
| String algorithm, SecretKeySpec skeySpec) throws IOException { |
| try { |
| this.storageOut = out; |
| this.algorithm = algorithm; |
| this.skeySpec = skeySpec; |
| |
| Cipher cipher = Cipher.getInstance(algorithm); |
| cipher.init(Cipher.ENCRYPT_MODE, skeySpec); |
| |
| this.cipherOut = new CipherOutputStream(out, cipher); |
| } catch (GeneralSecurityException e) { |
| throw (IOException) new IOException().initCause(e); |
| } |
| } |
| |
| @Override |
| public void close() throws IOException { |
| super.close(); |
| cipherOut.close(); |
| } |
| |
| @Override |
| protected void write0(byte[] buffer, int offset, int length) |
| throws IOException { |
| cipherOut.write(buffer, offset, length); |
| } |
| |
| @Override |
| protected Storage toStorage0() throws IOException { |
| // cipherOut has already been closed because toStorage calls close |
| Storage encrypted = storageOut.toStorage(); |
| return new CipherStorage(encrypted, algorithm, skeySpec); |
| } |
| } |
| |
| private static final class CipherStorage implements Storage { |
| private Storage encrypted; |
| private final String algorithm; |
| private final SecretKeySpec skeySpec; |
| |
| public CipherStorage(Storage encrypted, String algorithm, |
| SecretKeySpec skeySpec) { |
| this.encrypted = encrypted; |
| this.algorithm = algorithm; |
| this.skeySpec = skeySpec; |
| } |
| |
| public void delete() { |
| if (encrypted != null) { |
| encrypted.delete(); |
| encrypted = null; |
| } |
| } |
| |
| public InputStream getInputStream() throws IOException { |
| if (encrypted == null) |
| throw new IllegalStateException("storage has been deleted"); |
| |
| try { |
| Cipher cipher = Cipher.getInstance(algorithm); |
| cipher.init(Cipher.DECRYPT_MODE, skeySpec); |
| |
| InputStream in = encrypted.getInputStream(); |
| return new CipherInputStream(in, cipher); |
| } catch (GeneralSecurityException e) { |
| throw (IOException) new IOException().initCause(e); |
| } |
| } |
| } |
| |
| } |