1 files changed, 60 insertions, 0 deletions
diff --git a/java/com/android/libraries/entitlement/utils/BytesConverter.java b/java/com/android/libraries/entitlement/utils/BytesConverter.java
new file mode 100644
index 0000000..034ac9c
--- /dev/null
+++ b/java/com/android/libraries/entitlement/utils/BytesConverter.java
@@ -0,0 +1,60 @@
+/*
+ * Copyright (C) 2021 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 com.android.libraries.entitlement.eapaka.utils;
+
+import java.nio.ByteBuffer;
+
+import androidx.annotation.Nullable;
+
+public class BytesConverter {
+    private static final int INTEGER_SIZE = 4; // 4 bytes
+
+    // A table mapping from a number to a hex character for fast encoding hex strings.
+    private static final char[] HEX_CHARS = {
+            '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'
+    };
+
+    /**
+     * Converts a byte array into a String of hexadecimal characters.
+     *
+     * @param bytes an array of bytes
+     * @return hex string representation of bytes array
+     */
+    @Nullable
+    public static String convertBytesToHexString(byte[] bytes) {
+        if (bytes == null) {
+            return null;
+        }
+
+        StringBuilder ret = new StringBuilder(2 * bytes.length);
+
+        for (int i = 0; i < bytes.length; i++) {
+            int b;
+            b = 0x0f & (bytes[i] >> 4);
+            ret.append(HEX_CHARS[b]);
+            b = 0x0f & bytes[i];
+            ret.append(HEX_CHARS[b]);
+        }
+
+        return ret.toString();
+    }
+
+    /** Converts integer to 4 bytes. */
+    public static byte[] convertIntegerTo4Bytes(int value) {
+        return ByteBuffer.allocate(INTEGER_SIZE).putInt(value).array();
+    }
+}