/*
* Syncany, www.syncany.org
* Copyright (C) 2011-2014 Philipp C. Heckel <philipp.heckel@gmail.com>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program 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 for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package org.syncany.chunk;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import javax.crypto.spec.SecretKeySpec;
import org.syncany.crypto.CipherSession;
import org.syncany.crypto.CipherSpec;
import org.syncany.crypto.CipherSpecs;
import org.syncany.crypto.MultiCipherInputStream;
import org.syncany.crypto.MultiCipherOutputStream;
import org.syncany.crypto.SaltedSecretKey;
import org.syncany.util.StringUtil;
/**
* The CipherTransformer can be used to encrypt/decrypt files (typically
* {@link MultiChunk}s) using the {@link MultiCipherOutputStream} and
* {@link MultiCipherInputStream}.
*
* A CipherTransformer requires a list of {@link CipherSpec}s and the master
* key. It can be instantiated using a property list (from a config file) or
* by passing the dependencies to the constructor.
*
* @author Philipp C. Heckel <philipp.heckel@gmail.com>
*/
public class CipherTransformer extends Transformer {
public static final String TYPE = "cipher";
public static final String PROPERTY_CIPHER_SPECS = "cipherspecs";
public static final String PROPERTY_MASTER_KEY = "masterkey";
public static final String PROPERTY_MASTER_KEY_SALT = "mastersalt";
private List<CipherSpec> cipherSpecs;
private CipherSession cipherSession;
public CipherTransformer() {
this.cipherSpecs = new ArrayList<CipherSpec>();
this.cipherSession = null;
}
public CipherTransformer(List<CipherSpec> cipherSpecs, SaltedSecretKey masterKey) {
this.cipherSpecs = cipherSpecs;
this.cipherSession = new CipherSession(masterKey);
}
/**
* Initializes the cipher transformer using a settings map. Required settings
* are: {@link #PROPERTY_CIPHER_SPECS}, {@link #PROPERTY_MASTER_KEY} and
* {@link #PROPERTY_MASTER_KEY_SALT}.
*/
@Override
public void init(Map<String, String> settings) throws Exception {
String masterKeyStr = settings.get(PROPERTY_MASTER_KEY);
String masterKeySaltStr = settings.get(PROPERTY_MASTER_KEY);
String cipherSpecsListStr = settings.get(PROPERTY_CIPHER_SPECS);
if (masterKeyStr == null || masterKeySaltStr == null || cipherSpecsListStr == null) {
throw new Exception("Settings '"+PROPERTY_CIPHER_SPECS+"', '"+PROPERTY_MASTER_KEY+"' and '"+PROPERTY_MASTER_KEY_SALT+"' must both be filled.");
}
initCipherSpecs(cipherSpecsListStr);
initCipherSession(masterKeyStr, masterKeySaltStr);
}
private void initCipherSpecs(String cipherSpecListStr) throws Exception {
String[] cipherSpecIdStrs = cipherSpecListStr.split(",");
for (String cipherSpecIdStr : cipherSpecIdStrs) {
int cipherSpecId = Integer.parseInt(cipherSpecIdStr);
CipherSpec cipherSpec = CipherSpecs.getCipherSpec(cipherSpecId);
if (cipherSpec == null) {
throw new Exception("Cannot find cipher suite with ID '"+cipherSpecId+"'");
}
cipherSpecs.add(cipherSpec);
}
}
private void initCipherSession(String masterKeyStr, String masterKeySaltStr) {
byte[] masterKeySalt = StringUtil.fromHex(masterKeySaltStr);
byte[] masterKeyBytes = StringUtil.fromHex(masterKeyStr);
SaltedSecretKey masterKey = new SaltedSecretKey(new SecretKeySpec(masterKeyBytes, "RAW"), masterKeySalt);
cipherSession = new CipherSession(masterKey);
}
@Override
public OutputStream createOutputStream(OutputStream out) throws IOException {
if (cipherSession == null) {
throw new RuntimeException("Cipher session is not initialized. Call init() before!");
}
return new MultiCipherOutputStream(out, cipherSpecs, cipherSession);
}
@Override
public InputStream createInputStream(InputStream in) throws IOException {
if (cipherSession == null) {
throw new RuntimeException("Cipher session is not initialized. Call init() before!");
}
return new MultiCipherInputStream(in, cipherSession);
}
@Override
public String toString() {
return (nextTransformer == null) ? "Cipher" : "Cipher-"+nextTransformer;
}
}