1 /* 2 * Copyright (C) 2010 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package android.security; 18 19 import android.os.Environment; 20 import android.os.FileUtils; 21 22 import java.io.File; 23 import java.io.FileOutputStream; 24 import java.io.IOException; 25 import java.security.NoSuchAlgorithmException; 26 import java.security.SecureRandom; 27 28 import javax.crypto.KeyGenerator; 29 import javax.crypto.SecretKey; 30 31 import libcore.io.IoUtils; 32 33 /** 34 *@hide 35 */ 36 public class SystemKeyStore { 37 38 private static final String SYSTEM_KEYSTORE_DIRECTORY = "misc/systemkeys"; 39 private static final String KEY_FILE_EXTENSION = ".sks"; 40 private static SystemKeyStore mInstance = new SystemKeyStore(); 41 SystemKeyStore()42 private SystemKeyStore() { } 43 getInstance()44 public static SystemKeyStore getInstance() { 45 return mInstance; 46 } 47 toHexString(byte[] keyData)48 public static String toHexString(byte[] keyData) { 49 if (keyData == null) { 50 return null; 51 } 52 int keyLen = keyData.length; 53 int expectedStringLen = keyData.length * 2; 54 StringBuilder sb = new StringBuilder(expectedStringLen); 55 for (int i = 0; i < keyData.length; i++) { 56 String hexStr = Integer.toString(keyData[i] & 0x00FF, 16); 57 if (hexStr.length() == 1) { 58 hexStr = "0" + hexStr; 59 } 60 sb.append(hexStr); 61 } 62 return sb.toString(); 63 } 64 generateNewKeyHexString(int numBits, String algName, String keyName)65 public String generateNewKeyHexString(int numBits, String algName, String keyName) 66 throws NoSuchAlgorithmException { 67 return toHexString(generateNewKey(numBits, algName, keyName)); 68 } 69 generateNewKey(int numBits, String algName, String keyName)70 public byte[] generateNewKey(int numBits, String algName, String keyName) 71 throws NoSuchAlgorithmException { 72 73 // Check if key with similar name exists. If so, return null. 74 File keyFile = getKeyFile(keyName); 75 if (keyFile.exists()) { 76 throw new IllegalArgumentException(); 77 } 78 79 KeyGenerator skg = KeyGenerator.getInstance(algName); 80 SecureRandom srng = SecureRandom.getInstance("SHA1PRNG"); 81 skg.init(numBits, srng); 82 83 SecretKey sk = skg.generateKey(); 84 byte[] retKey = sk.getEncoded(); 85 86 try { 87 // Store the key 88 if (!keyFile.createNewFile()) { 89 throw new IllegalArgumentException(); 90 } 91 92 FileOutputStream fos = new FileOutputStream(keyFile); 93 fos.write(retKey); 94 fos.flush(); 95 FileUtils.sync(fos); 96 fos.close(); 97 FileUtils.setPermissions(keyFile.getName(), (FileUtils.S_IRUSR | FileUtils.S_IWUSR), 98 -1, -1); 99 } catch (IOException ioe) { 100 return null; 101 } 102 return retKey; 103 } 104 getKeyFile(String keyName)105 private File getKeyFile(String keyName) { 106 File sysKeystoreDir = new File(Environment.getDataDirectory(), 107 SYSTEM_KEYSTORE_DIRECTORY); 108 File keyFile = new File(sysKeystoreDir, keyName + KEY_FILE_EXTENSION); 109 return keyFile; 110 } 111 retrieveKeyHexString(String keyName)112 public String retrieveKeyHexString(String keyName) throws IOException { 113 return toHexString(retrieveKey(keyName)); 114 } 115 retrieveKey(String keyName)116 public byte[] retrieveKey(String keyName) throws IOException { 117 File keyFile = getKeyFile(keyName); 118 if (!keyFile.exists()) { 119 return null; 120 } 121 return IoUtils.readFileAsByteArray(keyFile.toString()); 122 } 123 deleteKey(String keyName)124 public void deleteKey(String keyName) { 125 126 // Get the file first. 127 File keyFile = getKeyFile(keyName); 128 if (!keyFile.exists()) { 129 throw new IllegalArgumentException(); 130 } 131 132 keyFile.delete(); 133 } 134 } 135