1 files changed, 299 insertions, 0 deletions
diff --git a/android/security/keystore/recovery/KeyChainSnapshot.java b/android/security/keystore/recovery/KeyChainSnapshot.java
new file mode 100644
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+++ b/android/security/keystore/recovery/KeyChainSnapshot.java
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+/*
+ * Copyright (C) 2017 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.keystore.recovery;
+
+import android.annotation.NonNull;
+import android.annotation.SystemApi;
+import android.os.Parcel;
+import android.os.Parcelable;
+
+import com.android.internal.util.Preconditions;
+
+import java.util.List;
+
+/**
+ * A snapshot of a version of the keystore. Two events can trigger the generation of a new snapshot:
+ *
+ * <ul>
+ *     <li>The user's lock screen changes. (A key derived from the user's lock screen is used to
+ *         protected the keychain, which is why this forces a new snapshot.)
+ *     <li>A key is added to or removed from the recoverable keychain.
+ * </ul>
+ *
+ * <p>The snapshot data is also encrypted with the remote trusted hardware's public key, so even
+ * the recovery agent itself should not be able to decipher the data. The recovery agent sends an
+ * instance of this to the remote trusted hardware whenever a new snapshot is generated. During a
+ * recovery flow, the recovery agent retrieves a snapshot from the remote trusted hardware. It then
+ * sends it to the framework, where it is decrypted using the user's lock screen from their previous
+ * device.
+ *
+ * @hide
+ */
+@SystemApi
+public final class KeyChainSnapshot implements Parcelable {
+    private static final int DEFAULT_MAX_ATTEMPTS = 10;
+    private static final long DEFAULT_COUNTER_ID = 1L;
+
+    private int mSnapshotVersion;
+    private int mMaxAttempts = DEFAULT_MAX_ATTEMPTS;
+    private long mCounterId = DEFAULT_COUNTER_ID;
+    private byte[] mServerParams;
+    private byte[] mPublicKey;
+    private List<KeyChainProtectionParams> mKeyChainProtectionParams;
+    private List<WrappedApplicationKey> mEntryRecoveryData;
+    private byte[] mEncryptedRecoveryKeyBlob;
+
+    /**
+     * @hide
+     * Deprecated, consider using builder.
+     */
+    public KeyChainSnapshot(
+            int snapshotVersion,
+            @NonNull List<KeyChainProtectionParams> keyChainProtectionParams,
+            @NonNull List<WrappedApplicationKey> wrappedApplicationKeys,
+            @NonNull byte[] encryptedRecoveryKeyBlob) {
+        mSnapshotVersion = snapshotVersion;
+        mKeyChainProtectionParams =
+                Preconditions.checkCollectionElementsNotNull(keyChainProtectionParams,
+                        "KeyChainProtectionParams");
+        mEntryRecoveryData = Preconditions.checkCollectionElementsNotNull(wrappedApplicationKeys,
+                "wrappedApplicationKeys");
+        mEncryptedRecoveryKeyBlob = Preconditions.checkNotNull(encryptedRecoveryKeyBlob);
+    }
+
+    private KeyChainSnapshot() {
+
+    }
+
+    /**
+     * Snapshot version for given account. It is incremented when user secret or list of application
+     * keys changes.
+     */
+    public int getSnapshotVersion() {
+        return mSnapshotVersion;
+    }
+
+    /**
+     * Number of user secret guesses allowed during Keychain recovery.
+     */
+    public int getMaxAttempts() {
+        return mMaxAttempts;
+    }
+
+    /**
+     * CounterId which is rotated together with user secret.
+     */
+    public long getCounterId() {
+        return mCounterId;
+    }
+
+    /**
+     * Server parameters.
+     */
+    public @NonNull byte[] getServerParams() {
+        return mServerParams;
+    }
+
+    /**
+     * Public key used to encrypt {@code encryptedRecoveryKeyBlob}.
+     *
+     * See implementation for binary key format
+     */
+    // TODO: document key format.
+    public @NonNull byte[] getTrustedHardwarePublicKey() {
+        return mPublicKey;
+    }
+
+    /**
+     * UI and key derivation parameters. Note that combination of secrets may be used.
+     */
+    public @NonNull List<KeyChainProtectionParams> getKeyChainProtectionParams() {
+        return mKeyChainProtectionParams;
+    }
+
+    /**
+     * List of application keys, with key material encrypted by
+     * the recovery key ({@link #getEncryptedRecoveryKeyBlob}).
+     */
+    public @NonNull List<WrappedApplicationKey> getWrappedApplicationKeys() {
+        return mEntryRecoveryData;
+    }
+
+    /**
+     * Recovery key blob, encrypted by user secret and recovery service public key.
+     */
+    public @NonNull byte[] getEncryptedRecoveryKeyBlob() {
+        return mEncryptedRecoveryKeyBlob;
+    }
+
+    public static final Creator<KeyChainSnapshot> CREATOR =
+            new Creator<KeyChainSnapshot>() {
+        public KeyChainSnapshot createFromParcel(Parcel in) {
+            return new KeyChainSnapshot(in);
+        }
+
+        public KeyChainSnapshot[] newArray(int length) {
+            return new KeyChainSnapshot[length];
+        }
+    };
+
+    /**
+     * Builder for creating {@link KeyChainSnapshot}.
+     * @hide
+     */
+    public static class Builder {
+        private KeyChainSnapshot mInstance = new KeyChainSnapshot();
+
+        /**
+         * Snapshot version for given account.
+         *
+         * @param snapshotVersion The snapshot version
+         * @return This builder.
+         */
+        public Builder setSnapshotVersion(int snapshotVersion) {
+            mInstance.mSnapshotVersion = snapshotVersion;
+            return this;
+        }
+
+        /**
+         * Sets the number of user secret guesses allowed during Keychain recovery.
+         *
+         * @param maxAttempts The maximum number of guesses.
+         * @return This builder.
+         */
+        public Builder setMaxAttempts(int maxAttempts) {
+            mInstance.mMaxAttempts = maxAttempts;
+            return this;
+        }
+
+        /**
+         * Sets counter id.
+         *
+         * @param counterId The counter id.
+         * @return This builder.
+         */
+        public Builder setCounterId(long counterId) {
+            mInstance.mCounterId = counterId;
+            return this;
+        }
+
+        /**
+         * Sets server parameters.
+         *
+         * @param serverParams The server parameters
+         * @return This builder.
+         */
+        public Builder setServerParams(byte[] serverParams) {
+            mInstance.mServerParams = serverParams;
+            return this;
+        }
+
+        /**
+         * Sets public key used to encrypt recovery blob.
+         *
+         * @param publicKey The public key
+         * @return This builder.
+         */
+        public Builder setTrustedHardwarePublicKey(byte[] publicKey) {
+            mInstance.mPublicKey = publicKey;
+            return this;
+        }
+
+        /**
+         * Sets UI and key derivation parameters
+         *
+         * @param recoveryMetadata The UI and key derivation parameters
+         * @return This builder.
+         */
+        public Builder setKeyChainProtectionParams(
+                @NonNull List<KeyChainProtectionParams> recoveryMetadata) {
+            mInstance.mKeyChainProtectionParams = recoveryMetadata;
+            return this;
+        }
+
+        /**
+         * List of application keys.
+         *
+         * @param entryRecoveryData List of application keys
+         * @return This builder.
+         */
+        public Builder setWrappedApplicationKeys(List<WrappedApplicationKey> entryRecoveryData) {
+            mInstance.mEntryRecoveryData = entryRecoveryData;
+            return this;
+        }
+
+        /**
+         * Sets recovery key blob
+         *
+         * @param encryptedRecoveryKeyBlob The recovery key blob.
+         * @return This builder.
+         */
+        public Builder setEncryptedRecoveryKeyBlob(@NonNull byte[] encryptedRecoveryKeyBlob) {
+            mInstance.mEncryptedRecoveryKeyBlob = encryptedRecoveryKeyBlob;
+            return this;
+        }
+
+
+        /**
+         * Creates a new {@link KeyChainSnapshot} instance.
+         *
+         * @return new instance
+         * @throws NullPointerException if some required fields were not set.
+         */
+        @NonNull public KeyChainSnapshot build() {
+            Preconditions.checkCollectionElementsNotNull(mInstance.mKeyChainProtectionParams,
+                    "recoveryMetadata");
+            Preconditions.checkCollectionElementsNotNull(mInstance.mEntryRecoveryData,
+                    "entryRecoveryData");
+            Preconditions.checkNotNull(mInstance.mEncryptedRecoveryKeyBlob);
+            Preconditions.checkNotNull(mInstance.mServerParams);
+            Preconditions.checkNotNull(mInstance.mPublicKey);
+            return mInstance;
+        }
+    }
+
+    @Override
+    public void writeToParcel(Parcel out, int flags) {
+        out.writeInt(mSnapshotVersion);
+        out.writeTypedList(mKeyChainProtectionParams);
+        out.writeByteArray(mEncryptedRecoveryKeyBlob);
+        out.writeTypedList(mEntryRecoveryData);
+        out.writeInt(mMaxAttempts);
+        out.writeLong(mCounterId);
+        out.writeByteArray(mServerParams);
+        out.writeByteArray(mPublicKey);
+    }
+
+    /**
+     * @hide
+     */
+    protected KeyChainSnapshot(Parcel in) {
+        mSnapshotVersion = in.readInt();
+        mKeyChainProtectionParams = in.createTypedArrayList(KeyChainProtectionParams.CREATOR);
+        mEncryptedRecoveryKeyBlob = in.createByteArray();
+        mEntryRecoveryData = in.createTypedArrayList(WrappedApplicationKey.CREATOR);
+        mMaxAttempts = in.readInt();
+        mCounterId = in.readLong();
+        mServerParams = in.createByteArray();
+        mPublicKey = in.createByteArray();
+    }
+
+    @Override
+    public int describeContents() {
+        return 0;
+    }
+}