/*
* Copyright 2015 Victor Albertos
*
* Licensed 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 io.rx_cache2.internal.encrypt;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.security.SecureRandom;
import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.CipherOutputStream;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
/**
* Encrypt/Decrypt the file data
*/
public final class BuiltInEncryptor implements Encryptor {
private static final int KEY_LENGTH = 128;
// Max 128 bits by default. See http://stackoverflow.com/a/24907555/5502014
private static final int FILE_BUF = 1024;
private Cipher encryptCipher;
private Cipher decryptCipher;
@Override public void encrypt(String key, File decryptedFile, File encryptedFile) {
initCiphers(key);
try {
CipherInputStream cis =
new CipherInputStream(new FileInputStream(decryptedFile), encryptCipher);
write(cis, new FileOutputStream(encryptedFile));
} catch (Exception e) {
e.printStackTrace();
}
}
@Override public void decrypt(String key, File encryptedFile, File decryptedFile) {
initCiphers(key);
try {
CipherOutputStream cos =
new CipherOutputStream(new FileOutputStream(decryptedFile), decryptCipher);
write(new FileInputStream(encryptedFile), cos);
} catch (Exception e) {
e.printStackTrace();
}
}
private void initCiphers(String key) {
try {
SecretKeySpec secretKey = generateSecretKey(key);
encryptCipher = Cipher.getInstance("AES");
encryptCipher.init(Cipher.ENCRYPT_MODE, secretKey);
decryptCipher = Cipher.getInstance("AES");
decryptCipher.init(Cipher.DECRYPT_MODE, secretKey);
} catch (Exception e) {
e.printStackTrace();
}
}
private SecretKeySpec generateSecretKey(String key) throws Exception {
SecureRandom secureRandom = SecureRandom.getInstance("SHA1PRNG");
secureRandom.setSeed(key.getBytes("UTF-8"));
KeyGenerator keyGenerator = KeyGenerator.getInstance("AES");
keyGenerator.init(KEY_LENGTH, secureRandom);
SecretKey secretKey = keyGenerator.generateKey();
return new SecretKeySpec(secretKey.getEncoded(), "AES");
}
private void write(InputStream is, OutputStream os) {
byte[] bytes = new byte[FILE_BUF];
int numBytes;
try {
while ((numBytes = is.read(bytes)) != -1) {
os.write(bytes, 0, numBytes);
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
is.close();
os.flush();
os.close();
} catch (IOException ex) {
ex.printStackTrace();
}
}
}
}