diff --git a/sop-java/src/main/java/sop/util/HexUtil.java b/sop-java/src/main/java/sop/util/HexUtil.java
deleted file mode 100644
index 9b88f53..0000000
--- a/sop-java/src/main/java/sop/util/HexUtil.java
+++ /dev/null
@@ -1,47 +0,0 @@
-// Copyright 2021 Paul Schaub, @maybeWeCouldStealAVan, @Dave L.
-// SPDX-FileCopyrightText: 2021 Paul Schaub <vanitasvitae@fsfe.org>
-//
-// SPDX-License-Identifier: Apache-2.0
-
-package sop.util;
-
-public class HexUtil {
-
-    private static final char[] HEX_ARRAY = "0123456789ABCDEF".toCharArray();
-
-    /**
-     * Encode a byte array to a hex string.
-     *
-     * @see <a href="https://stackoverflow.com/a/9855338">
-     *     How to convert a byte array to a hex string in Java?</a>
-     * @param bytes bytes
-     * @return hex encoding
-     */
-    public static String bytesToHex(byte[] bytes) {
-        char[] hexChars = new char[bytes.length * 2];
-        for (int j = 0; j < bytes.length; j++) {
-            int v = bytes[j] & 0xFF;
-            hexChars[j * 2] = HEX_ARRAY[v >>> 4];
-            hexChars[j * 2 + 1] = HEX_ARRAY[v & 0x0F];
-        }
-        return new String(hexChars);
-    }
-
-    /**
-     * Decode a hex string into a byte array.
-     *
-     * @see <a href="https://stackoverflow.com/a/140861">
-     *     Convert a string representation of a hex dump to a byte array using Java?</a>
-     * @param s hex string
-     * @return decoded byte array
-     */
-    public static byte[] hexToBytes(String s) {
-        int len = s.length();
-        byte[] data = new byte[len / 2];
-        for (int i = 0; i < len; i += 2) {
-            data[i / 2] = (byte) ((Character.digit(s.charAt(i), 16) << 4)
-                    + Character.digit(s.charAt(i + 1), 16));
-        }
-        return data;
-    }
-}
diff --git a/sop-java/src/main/kotlin/sop/util/HexUtil.kt b/sop-java/src/main/kotlin/sop/util/HexUtil.kt
new file mode 100644
index 0000000..f372137
--- /dev/null
+++ b/sop-java/src/main/kotlin/sop/util/HexUtil.kt
@@ -0,0 +1,38 @@
+// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package sop.util
+
+class HexUtil {
+
+    companion object {
+        /**
+         * Encode a byte array to a hex string.
+         *
+         * @param bytes bytes
+         * @return hex encoding
+         * @see
+         *   [Convert Byte Arrays to Hex Strings in Kotlin](https://www.baeldung.com/kotlin/byte-arrays-to-hex-strings)
+         */
+        @JvmStatic fun bytesToHex(bytes: ByteArray): String = bytes.toHex()
+
+        /**
+         * Decode a hex string into a byte array.
+         *
+         * @param s hex string
+         * @return decoded byte array
+         * @see
+         *   [Kotlin convert hex string to ByteArray](https://stackoverflow.com/a/66614516/11150851)
+         */
+        @JvmStatic fun hexToBytes(s: String): ByteArray = s.decodeHex()
+    }
+}
+
+fun String.decodeHex(): ByteArray {
+    check(length % 2 == 0) { "Hex encoding must have even number of digits." }
+
+    return chunked(2).map { it.toInt(16).toByte() }.toByteArray()
+}
+
+fun ByteArray.toHex(): String = joinToString(separator = "") { eachByte -> "%02X".format(eachByte) }