1 /* 2 * Copyright (C) 2017 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 com.android.server.locksettings.recoverablekeystore; 18 19 import static org.junit.Assert.assertArrayEquals; 20 import static org.junit.Assert.assertEquals; 21 import static org.junit.Assert.assertTrue; 22 import static org.junit.Assert.fail; 23 24 import android.security.keystore.AndroidKeyStoreSecretKey; 25 import android.security.keystore.KeyGenParameterSpec; 26 import android.security.keystore.KeyProperties; 27 import android.support.test.filters.SmallTest; 28 import android.support.test.runner.AndroidJUnit4; 29 30 import org.junit.After; 31 import org.junit.Test; 32 import org.junit.runner.RunWith; 33 34 import java.security.KeyStore; 35 import java.util.HashMap; 36 import java.util.Map; 37 38 import javax.crypto.Cipher; 39 import javax.crypto.KeyGenerator; 40 import javax.crypto.SecretKey; 41 import javax.crypto.spec.GCMParameterSpec; 42 43 @SmallTest 44 @RunWith(AndroidJUnit4.class) 45 public class WrappedKeyTest { 46 private static final String ANDROID_KEY_STORE_PROVIDER = "AndroidKeyStore"; 47 private static final String KEY_ALGORITHM = "AES"; 48 private static final String CIPHER_ALGORITHM = "AES/GCM/NoPadding"; 49 private static final String WRAPPING_KEY_ALIAS = "WrappedKeyTestWrappingKeyAlias"; 50 private static final int GENERATION_ID = 1; 51 private static final int GCM_TAG_LENGTH_BYTES = 16; 52 private static final int BITS_PER_BYTE = 8; 53 private static final int GCM_TAG_LENGTH_BITS = GCM_TAG_LENGTH_BYTES * BITS_PER_BYTE; 54 55 @After 56 public void tearDown() throws Exception { 57 KeyStore keyStore = KeyStore.getInstance(ANDROID_KEY_STORE_PROVIDER); 58 keyStore.load(/*param=*/ null); 59 keyStore.deleteEntry(WRAPPING_KEY_ALIAS); 60 } 61 62 @Test 63 public void fromSecretKey_createsWrappedKeyThatCanBeUnwrapped() throws Exception { 64 PlatformEncryptionKey wrappingKey = new PlatformEncryptionKey( 65 GENERATION_ID, generateAndroidKeyStoreKey()); 66 SecretKey rawKey = generateKey(); 67 68 WrappedKey wrappedKey = WrappedKey.fromSecretKey(wrappingKey, rawKey); 69 70 Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM); 71 cipher.init( 72 Cipher.UNWRAP_MODE, 73 wrappingKey.getKey(), 74 new GCMParameterSpec(GCM_TAG_LENGTH_BITS, wrappedKey.getNonce())); 75 SecretKey unwrappedKey = (SecretKey) cipher.unwrap( 76 wrappedKey.getKeyMaterial(), KEY_ALGORITHM, Cipher.SECRET_KEY); 77 assertEquals(rawKey, unwrappedKey); 78 } 79 80 @Test 81 public void fromSecretKey_returnsAKeyWithTheGenerationIdOfTheWrappingKey() throws Exception { 82 PlatformEncryptionKey wrappingKey = new PlatformEncryptionKey( 83 GENERATION_ID, generateAndroidKeyStoreKey()); 84 SecretKey rawKey = generateKey(); 85 86 WrappedKey wrappedKey = WrappedKey.fromSecretKey(wrappingKey, rawKey); 87 88 assertEquals(GENERATION_ID, wrappedKey.getPlatformKeyGenerationId()); 89 } 90 91 @Test 92 public void decryptWrappedKeys_decryptsWrappedKeys() throws Exception { 93 String alias = "karlin"; 94 AndroidKeyStoreSecretKey platformKey = generateAndroidKeyStoreKey(); 95 SecretKey appKey = generateKey(); 96 WrappedKey wrappedKey = WrappedKey.fromSecretKey( 97 new PlatformEncryptionKey(GENERATION_ID, platformKey), appKey); 98 HashMap<String, WrappedKey> keysByAlias = new HashMap<>(); 99 keysByAlias.put(alias, wrappedKey); 100 101 Map<String, SecretKey> unwrappedKeys = WrappedKey.unwrapKeys( 102 new PlatformDecryptionKey(GENERATION_ID, platformKey), keysByAlias); 103 104 assertEquals(1, unwrappedKeys.size()); 105 assertTrue(unwrappedKeys.containsKey(alias)); 106 assertArrayEquals(appKey.getEncoded(), unwrappedKeys.get(alias).getEncoded()); 107 } 108 109 @Test 110 public void decryptWrappedKeys_doesNotDieIfSomeKeysAreUnwrappable() throws Exception { 111 String alias = "karlin"; 112 AndroidKeyStoreSecretKey platformKey = generateAndroidKeyStoreKey(); 113 SecretKey appKey = generateKey(); 114 WrappedKey wrappedKey = WrappedKey.fromSecretKey( 115 new PlatformEncryptionKey(GENERATION_ID, platformKey), appKey); 116 HashMap<String, WrappedKey> keysByAlias = new HashMap<>(); 117 keysByAlias.put(alias, wrappedKey); 118 119 Map<String, SecretKey> unwrappedKeys = WrappedKey.unwrapKeys( 120 new PlatformDecryptionKey(GENERATION_ID, generateAndroidKeyStoreKey()), 121 keysByAlias); 122 123 assertEquals(0, unwrappedKeys.size()); 124 } 125 126 @Test 127 public void decryptWrappedKeys_throwsIfPlatformKeyGenerationIdDoesNotMatch() throws Exception { 128 AndroidKeyStoreSecretKey platformKey = generateAndroidKeyStoreKey(); 129 WrappedKey wrappedKey = WrappedKey.fromSecretKey( 130 new PlatformEncryptionKey(GENERATION_ID, platformKey), generateKey()); 131 HashMap<String, WrappedKey> keysByAlias = new HashMap<>(); 132 keysByAlias.put("benji", wrappedKey); 133 134 try { 135 WrappedKey.unwrapKeys( 136 new PlatformDecryptionKey(/*generationId=*/ 2, platformKey), 137 keysByAlias); 138 fail("Should have thrown."); 139 } catch (BadPlatformKeyException e) { 140 assertEquals( 141 "WrappedKey with alias 'benji' was wrapped with platform key 1," 142 + " not platform key 2", 143 e.getMessage()); 144 } 145 } 146 147 private SecretKey generateKey() throws Exception { 148 KeyGenerator keyGenerator = KeyGenerator.getInstance(KEY_ALGORITHM); 149 keyGenerator.init(/*keySize=*/ 256); 150 return keyGenerator.generateKey(); 151 } 152 153 private AndroidKeyStoreSecretKey generateAndroidKeyStoreKey() throws Exception { 154 KeyGenerator keyGenerator = KeyGenerator.getInstance( 155 KEY_ALGORITHM, 156 ANDROID_KEY_STORE_PROVIDER); 157 keyGenerator.init(new KeyGenParameterSpec.Builder( 158 WRAPPING_KEY_ALIAS, 159 KeyProperties.PURPOSE_ENCRYPT | KeyProperties.PURPOSE_DECRYPT) 160 .setBlockModes(KeyProperties.BLOCK_MODE_GCM) 161 .setEncryptionPaddings(KeyProperties.ENCRYPTION_PADDING_NONE) 162 .build()); 163 return (AndroidKeyStoreSecretKey) keyGenerator.generateKey(); 164 } 165 166 private PlatformDecryptionKey generatePlatformDecryptionKey() throws Exception { 167 return generatePlatformDecryptionKey(GENERATION_ID); 168 } 169 170 private PlatformDecryptionKey generatePlatformDecryptionKey(int generationId) throws Exception { 171 return new PlatformDecryptionKey(generationId, generateAndroidKeyStoreKey()); 172 } 173 } 174
