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/*
* Copyright (C) 2010 The Android Open Source Project
*
* 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 android.security;
import android.os.Environment;
import android.os.FileUtils;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import libcore.io.IoUtils;
/**
*@hide
*/
public class SystemKeyStore {
private static final String SYSTEM_KEYSTORE_DIRECTORY = "misc/systemkeys";
private static final String KEY_FILE_EXTENSION = ".sks";
private static SystemKeyStore mInstance = new SystemKeyStore();
private SystemKeyStore() { }
public static SystemKeyStore getInstance() {
return mInstance;
}
public static String toHexString(byte[] keyData) {
if (keyData == null) {
return null;
}
int keyLen = keyData.length;
int expectedStringLen = keyData.length * 2;
StringBuilder sb = new StringBuilder(expectedStringLen);
for (int i = 0; i < keyData.length; i++) {
String hexStr = Integer.toString(keyData[i] & 0x00FF, 16);
if (hexStr.length() == 1) {
hexStr = "0" + hexStr;
}
sb.append(hexStr);
}
return sb.toString();
}
public String generateNewKeyHexString(int numBits, String algName, String keyName)
throws NoSuchAlgorithmException {
return toHexString(generateNewKey(numBits, algName, keyName));
}
public byte[] generateNewKey(int numBits, String algName, String keyName)
throws NoSuchAlgorithmException {
// Check if key with similar name exists. If so, return null.
File keyFile = getKeyFile(keyName);
if (keyFile.exists()) {
throw new IllegalArgumentException();
}
KeyGenerator skg = KeyGenerator.getInstance(algName);
SecureRandom srng = SecureRandom.getInstance("SHA1PRNG");
skg.init(numBits, srng);
SecretKey sk = skg.generateKey();
byte[] retKey = sk.getEncoded();
try {
// Store the key
if (!keyFile.createNewFile()) {
throw new IllegalArgumentException();
}
FileOutputStream fos = new FileOutputStream(keyFile);
fos.write(retKey);
fos.flush();
FileUtils.sync(fos);
fos.close();
FileUtils.setPermissions(keyFile.getName(), (FileUtils.S_IRUSR | FileUtils.S_IWUSR),
-1, -1);
} catch (IOException ioe) {
return null;
}
return retKey;
}
private File getKeyFile(String keyName) {
File sysKeystoreDir = new File(Environment.getDataDirectory(),
SYSTEM_KEYSTORE_DIRECTORY);
File keyFile = new File(sysKeystoreDir, keyName + KEY_FILE_EXTENSION);
return keyFile;
}
public String retrieveKeyHexString(String keyName) throws IOException {
return toHexString(retrieveKey(keyName));
}
public byte[] retrieveKey(String keyName) throws IOException {
File keyFile = getKeyFile(keyName);
if (!keyFile.exists()) {
return null;
}
return IoUtils.readFileAsByteArray(keyFile.toString());
}
public void deleteKey(String keyName) {
// Get the file first.
File keyFile = getKeyFile(keyName);
if (!keyFile.exists()) {
throw new IllegalArgumentException();
}
keyFile.delete();
}
}
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