1 files changed, 75 insertions, 0 deletions
diff --git a/keystore/java/android/security/AuthTokenUtils.java b/keystore/java/android/security/AuthTokenUtils.java
new file mode 100644
index 000000000000..14d6626e5e97
--- /dev/null
+++ b/keystore/java/android/security/AuthTokenUtils.java
@@ -0,0 +1,75 @@
+/*
+ * Copyright (C) 2020 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.annotation.NonNull;
+import android.hardware.security.keymint.HardwareAuthToken;
+import android.hardware.security.keymint.Timestamp;
+
+import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
+
+/**
+ * @hide This Utils class provides method(s) for AuthToken conversion.
+ */
+public class AuthTokenUtils {
+
+    private AuthTokenUtils(){
+    }
+
+    /**
+     * Build a HardwareAuthToken from a byte array
+     * @param array byte array representing an auth token
+     * @return HardwareAuthToken representation of an auth token
+     */
+    public static @NonNull HardwareAuthToken toHardwareAuthToken(@NonNull byte[] array) {
+        final HardwareAuthToken hardwareAuthToken = new HardwareAuthToken();
+
+        // First byte is version, which does not exist in HardwareAuthToken anymore
+        // Next 8 bytes is the challenge.
+        hardwareAuthToken.challenge =
+                ByteBuffer.wrap(array, 1, 8).order(ByteOrder.nativeOrder()).getLong();
+
+        // Next 8 bytes is the userId
+        hardwareAuthToken.userId =
+                ByteBuffer.wrap(array, 9, 8).order(ByteOrder.nativeOrder()).getLong();
+
+        // Next 8 bytes is the authenticatorId.
+        hardwareAuthToken.authenticatorId =
+                ByteBuffer.wrap(array, 17, 8).order(ByteOrder.nativeOrder()).getLong();
+
+        // while the other fields are in machine byte order, authenticatorType and timestamp
+        // are in network byte order.
+        // Next 4 bytes is the authenticatorType.
+        hardwareAuthToken.authenticatorType =
+                ByteBuffer.wrap(array, 25, 4).order(ByteOrder.BIG_ENDIAN).getInt();
+        // Next 8 bytes is the timestamp.
+        final Timestamp timestamp = new Timestamp();
+        timestamp.milliSeconds =
+                ByteBuffer.wrap(array, 29, 8).order(ByteOrder.BIG_ENDIAN).getLong();
+        hardwareAuthToken.timestamp = timestamp;
+
+        // Last 32 bytes is the mac, 37:69
+        hardwareAuthToken.mac = new byte[32];
+        System.arraycopy(array, 37 /* srcPos */,
+                hardwareAuthToken.mac,
+                0 /* destPos */,
+                32 /* length */);
+
+        return hardwareAuthToken;
+    }
+}