Robert Berry | 25f5135 | 2018-03-28 20:26:57 +0100 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2018 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.serialization; |
| 18 | |
| 19 | |
| 20 | import static com.android.server.locksettings.recoverablekeystore.serialization.KeyChainSnapshotSchema.CERT_PATH_ENCODING; |
| 21 | import static com.android.server.locksettings.recoverablekeystore.serialization.KeyChainSnapshotSchema.NAMESPACE; |
| 22 | import static com.android.server.locksettings.recoverablekeystore.serialization.KeyChainSnapshotSchema.OUTPUT_ENCODING; |
| 23 | import static com.android.server.locksettings.recoverablekeystore.serialization.KeyChainSnapshotSchema.TAG_ALGORITHM; |
| 24 | import static com.android.server.locksettings.recoverablekeystore.serialization.KeyChainSnapshotSchema.TAG_ALIAS; |
| 25 | import static com.android.server.locksettings.recoverablekeystore.serialization.KeyChainSnapshotSchema.TAG_APPLICATION_KEY; |
| 26 | import static com.android.server.locksettings.recoverablekeystore.serialization.KeyChainSnapshotSchema.TAG_APPLICATION_KEYS; |
| 27 | import static com.android.server.locksettings.recoverablekeystore.serialization.KeyChainSnapshotSchema.TAG_COUNTER_ID; |
| 28 | import static com.android.server.locksettings.recoverablekeystore.serialization.KeyChainSnapshotSchema.TAG_RECOVERY_KEY_MATERIAL; |
| 29 | import static com.android.server.locksettings.recoverablekeystore.serialization.KeyChainSnapshotSchema.TAG_KEY_CHAIN_PROTECTION_PARAMS; |
| 30 | import static com.android.server.locksettings.recoverablekeystore.serialization.KeyChainSnapshotSchema.TAG_KEY_CHAIN_PROTECTION_PARAMS_LIST; |
| 31 | import static com.android.server.locksettings.recoverablekeystore.serialization.KeyChainSnapshotSchema.TAG_KEY_CHAIN_SNAPSHOT; |
| 32 | import static com.android.server.locksettings.recoverablekeystore.serialization.KeyChainSnapshotSchema.TAG_KEY_DERIVATION_PARAMS; |
| 33 | import static com.android.server.locksettings.recoverablekeystore.serialization.KeyChainSnapshotSchema.TAG_KEY_MATERIAL; |
| 34 | import static com.android.server.locksettings.recoverablekeystore.serialization.KeyChainSnapshotSchema.TAG_LOCK_SCREEN_UI_TYPE; |
| 35 | import static com.android.server.locksettings.recoverablekeystore.serialization.KeyChainSnapshotSchema.TAG_MAX_ATTEMPTS; |
| 36 | import static com.android.server.locksettings.recoverablekeystore.serialization.KeyChainSnapshotSchema.TAG_MEMORY_DIFFICULTY; |
| 37 | import static com.android.server.locksettings.recoverablekeystore.serialization.KeyChainSnapshotSchema.TAG_SALT; |
| 38 | import static com.android.server.locksettings.recoverablekeystore.serialization.KeyChainSnapshotSchema.TAG_SERVER_PARAMS; |
| 39 | import static com.android.server.locksettings.recoverablekeystore.serialization.KeyChainSnapshotSchema.TAG_SNAPSHOT_VERSION; |
| 40 | import static com.android.server.locksettings.recoverablekeystore.serialization.KeyChainSnapshotSchema.TAG_TRUSTED_HARDWARE_CERT_PATH; |
| 41 | import static com.android.server.locksettings.recoverablekeystore.serialization.KeyChainSnapshotSchema.TAG_USER_SECRET_TYPE; |
| 42 | |
| 43 | import android.security.keystore.recovery.KeyChainProtectionParams; |
| 44 | import android.security.keystore.recovery.KeyChainSnapshot; |
| 45 | import android.security.keystore.recovery.KeyDerivationParams; |
| 46 | import android.security.keystore.recovery.WrappedApplicationKey; |
| 47 | import android.util.Base64; |
| 48 | import android.util.Xml; |
| 49 | |
| 50 | import org.xmlpull.v1.XmlSerializer; |
| 51 | |
| 52 | import java.io.IOException; |
| 53 | import java.io.OutputStream; |
| 54 | import java.security.cert.CertPath; |
| 55 | import java.security.cert.CertificateEncodingException; |
| 56 | import java.util.List; |
| 57 | |
| 58 | /** |
| 59 | * Serializes a {@link KeyChainSnapshot} instance to XML. |
| 60 | */ |
| 61 | public class KeyChainSnapshotSerializer { |
| 62 | |
| 63 | /** |
| 64 | * Serializes {@code keyChainSnapshot} to XML, writing to {@code outputStream}. |
| 65 | * |
| 66 | * @throws IOException if there was an IO error writing to the stream. |
| 67 | * @throws CertificateEncodingException if the {@link CertPath} from |
| 68 | * {@link KeyChainSnapshot#getTrustedHardwareCertPath()} is not encoded correctly. |
| 69 | */ |
| 70 | public static void serialize(KeyChainSnapshot keyChainSnapshot, OutputStream outputStream) |
| 71 | throws IOException, CertificateEncodingException { |
| 72 | XmlSerializer xmlSerializer = Xml.newSerializer(); |
| 73 | xmlSerializer.setOutput(outputStream, OUTPUT_ENCODING); |
| 74 | xmlSerializer.startDocument( |
| 75 | /*encoding=*/ null, |
| 76 | /*standalone=*/ null); |
| 77 | xmlSerializer.startTag(NAMESPACE, TAG_KEY_CHAIN_SNAPSHOT); |
| 78 | writeKeyChainSnapshotProperties(xmlSerializer, keyChainSnapshot); |
| 79 | writeKeyChainProtectionParams(xmlSerializer, |
| 80 | keyChainSnapshot.getKeyChainProtectionParams()); |
| 81 | writeApplicationKeys(xmlSerializer, |
| 82 | keyChainSnapshot.getWrappedApplicationKeys()); |
| 83 | xmlSerializer.endTag(NAMESPACE, TAG_KEY_CHAIN_SNAPSHOT); |
| 84 | xmlSerializer.endDocument(); |
| 85 | } |
| 86 | |
| 87 | private static void writeApplicationKeys( |
| 88 | XmlSerializer xmlSerializer, List<WrappedApplicationKey> wrappedApplicationKeys) |
| 89 | throws IOException { |
| 90 | xmlSerializer.startTag(NAMESPACE, TAG_APPLICATION_KEYS); |
| 91 | for (WrappedApplicationKey key : wrappedApplicationKeys) { |
| 92 | xmlSerializer.startTag(NAMESPACE, TAG_APPLICATION_KEY); |
| 93 | writeApplicationKeyProperties(xmlSerializer, key); |
| 94 | xmlSerializer.endTag(NAMESPACE, TAG_APPLICATION_KEY); |
| 95 | } |
| 96 | xmlSerializer.endTag(NAMESPACE, TAG_APPLICATION_KEYS); |
| 97 | } |
| 98 | |
| 99 | private static void writeApplicationKeyProperties( |
| 100 | XmlSerializer xmlSerializer, WrappedApplicationKey applicationKey) throws IOException { |
| 101 | writePropertyTag(xmlSerializer, TAG_ALIAS, applicationKey.getAlias()); |
| 102 | writePropertyTag(xmlSerializer, TAG_KEY_MATERIAL, applicationKey.getEncryptedKeyMaterial()); |
| 103 | } |
| 104 | |
| 105 | private static void writeKeyChainProtectionParams( |
| 106 | XmlSerializer xmlSerializer, |
| 107 | List<KeyChainProtectionParams> keyChainProtectionParamsList) throws IOException { |
| 108 | xmlSerializer.startTag(NAMESPACE, TAG_KEY_CHAIN_PROTECTION_PARAMS_LIST); |
| 109 | for (KeyChainProtectionParams keyChainProtectionParams : keyChainProtectionParamsList) { |
| 110 | xmlSerializer.startTag(NAMESPACE, TAG_KEY_CHAIN_PROTECTION_PARAMS); |
| 111 | writeKeyChainProtectionParamsProperties(xmlSerializer, keyChainProtectionParams); |
| 112 | xmlSerializer.endTag(NAMESPACE, TAG_KEY_CHAIN_PROTECTION_PARAMS); |
| 113 | } |
| 114 | xmlSerializer.endTag(NAMESPACE, TAG_KEY_CHAIN_PROTECTION_PARAMS_LIST); |
| 115 | } |
| 116 | |
| 117 | private static void writeKeyChainProtectionParamsProperties( |
| 118 | XmlSerializer xmlSerializer, KeyChainProtectionParams keyChainProtectionParams) |
| 119 | throws IOException { |
| 120 | writePropertyTag(xmlSerializer, TAG_USER_SECRET_TYPE, |
| 121 | keyChainProtectionParams.getUserSecretType()); |
| 122 | writePropertyTag(xmlSerializer, TAG_LOCK_SCREEN_UI_TYPE, |
| 123 | keyChainProtectionParams.getLockScreenUiFormat()); |
| 124 | |
| 125 | // NOTE: Do not serialize the 'secret' field. It should never be set anyway for snapshots |
| 126 | // we generate. |
| 127 | |
| 128 | writeKeyDerivationParams(xmlSerializer, keyChainProtectionParams.getKeyDerivationParams()); |
| 129 | } |
| 130 | |
| 131 | private static void writeKeyDerivationParams( |
| 132 | XmlSerializer xmlSerializer, KeyDerivationParams keyDerivationParams) |
| 133 | throws IOException { |
| 134 | xmlSerializer.startTag(NAMESPACE, TAG_KEY_DERIVATION_PARAMS); |
| 135 | writeKeyDerivationParamsProperties( |
| 136 | xmlSerializer, keyDerivationParams); |
| 137 | xmlSerializer.endTag(NAMESPACE, TAG_KEY_DERIVATION_PARAMS); |
| 138 | } |
| 139 | |
| 140 | private static void writeKeyDerivationParamsProperties( |
| 141 | XmlSerializer xmlSerializer, KeyDerivationParams keyDerivationParams) |
| 142 | throws IOException { |
| 143 | writePropertyTag(xmlSerializer, TAG_ALGORITHM, keyDerivationParams.getAlgorithm()); |
| 144 | writePropertyTag(xmlSerializer, TAG_SALT, keyDerivationParams.getSalt()); |
| 145 | writePropertyTag(xmlSerializer, TAG_MEMORY_DIFFICULTY, |
| 146 | keyDerivationParams.getMemoryDifficulty()); |
| 147 | } |
| 148 | |
| 149 | private static void writeKeyChainSnapshotProperties( |
| 150 | XmlSerializer xmlSerializer, KeyChainSnapshot keyChainSnapshot) |
| 151 | throws IOException, CertificateEncodingException { |
| 152 | |
| 153 | writePropertyTag(xmlSerializer, TAG_SNAPSHOT_VERSION, |
| 154 | keyChainSnapshot.getSnapshotVersion()); |
| 155 | writePropertyTag(xmlSerializer, TAG_MAX_ATTEMPTS, keyChainSnapshot.getMaxAttempts()); |
| 156 | writePropertyTag(xmlSerializer, TAG_COUNTER_ID, keyChainSnapshot.getCounterId()); |
| 157 | writePropertyTag(xmlSerializer, TAG_RECOVERY_KEY_MATERIAL, |
| 158 | keyChainSnapshot.getEncryptedRecoveryKeyBlob()); |
| 159 | writePropertyTag(xmlSerializer, TAG_SERVER_PARAMS, keyChainSnapshot.getServerParams()); |
| 160 | writePropertyTag(xmlSerializer, TAG_TRUSTED_HARDWARE_CERT_PATH, |
| 161 | keyChainSnapshot.getTrustedHardwareCertPath()); |
| 162 | } |
| 163 | |
| 164 | private static void writePropertyTag( |
| 165 | XmlSerializer xmlSerializer, String propertyName, long propertyValue) |
| 166 | throws IOException { |
| 167 | xmlSerializer.startTag(NAMESPACE, propertyName); |
| 168 | xmlSerializer.text(Long.toString(propertyValue)); |
| 169 | xmlSerializer.endTag(NAMESPACE, propertyName); |
| 170 | } |
| 171 | |
| 172 | private static void writePropertyTag( |
| 173 | XmlSerializer xmlSerializer, String propertyName, String propertyValue) |
| 174 | throws IOException { |
| 175 | xmlSerializer.startTag(NAMESPACE, propertyName); |
| 176 | xmlSerializer.text(propertyValue); |
| 177 | xmlSerializer.endTag(NAMESPACE, propertyName); |
| 178 | } |
| 179 | |
| 180 | private static void writePropertyTag( |
| 181 | XmlSerializer xmlSerializer, String propertyName, byte[] propertyValue) |
| 182 | throws IOException { |
| 183 | xmlSerializer.startTag(NAMESPACE, propertyName); |
| 184 | xmlSerializer.text(Base64.encodeToString(propertyValue, /*flags=*/ Base64.DEFAULT)); |
| 185 | xmlSerializer.endTag(NAMESPACE, propertyName); |
| 186 | } |
| 187 | |
| 188 | private static void writePropertyTag( |
| 189 | XmlSerializer xmlSerializer, String propertyName, CertPath certPath) |
| 190 | throws IOException, CertificateEncodingException { |
| 191 | writePropertyTag(xmlSerializer, propertyName, certPath.getEncoded(CERT_PATH_ENCODING)); |
| 192 | } |
| 193 | |
| 194 | // Statics only |
| 195 | private KeyChainSnapshotSerializer() {} |
| 196 | } |