diff --git a/app/src/main/java/io/legado/app/utils/MD5Utils.java b/app/src/main/java/io/legado/app/utils/MD5Utils.java
deleted file mode 100644
index d4f0d8a12..000000000
--- a/app/src/main/java/io/legado/app/utils/MD5Utils.java
+++ /dev/null
@@ -1,40 +0,0 @@
-package io.legado.app.utils;
-
-import java.security.MessageDigest;
-import java.security.NoSuchAlgorithmException;
-
-/**
- * 将字符串转化为MD5
- */
-
-public class MD5Utils {
-
-    public static String strToMd5By32(String str) {
-        if (str == null) return null;
-        String reStr = null;
-        try {
-            MessageDigest md5 = MessageDigest.getInstance("MD5");
-            byte[] bytes = md5.digest(str.getBytes());
-            StringBuilder stringBuffer = new StringBuilder();
-            for (byte b : bytes) {
-                int bt = b & 0xff;
-                if (bt < 16) {
-                    stringBuffer.append(0);
-                }
-                stringBuffer.append(Integer.toHexString(bt));
-            }
-            reStr = stringBuffer.toString();
-        } catch (NoSuchAlgorithmException e) {
-            e.printStackTrace();
-        }
-        return reStr;
-    }
-
-    public static String strToMd5By16(String str) {
-        String reStr = strToMd5By32(str);
-        if (reStr != null) {
-            reStr = reStr.substring(8, 24);
-        }
-        return reStr;
-    }
-}
diff --git a/app/src/main/java/io/legado/app/utils/MD5Utils.kt b/app/src/main/java/io/legado/app/utils/MD5Utils.kt
new file mode 100644
index 000000000..dda1df688
--- /dev/null
+++ b/app/src/main/java/io/legado/app/utils/MD5Utils.kt
@@ -0,0 +1,41 @@
+package io.legado.app.utils
+
+import java.security.MessageDigest
+import java.security.NoSuchAlgorithmException
+
+/**
+ * 将字符串转化为MD5
+ */
+
+object MD5Utils {
+
+    fun strToMd5By32(str: String?): String? {
+        if (str == null) return null
+        var reStr: String? = null
+        try {
+            val md5:MessageDigest = MessageDigest.getInstance("MD5")
+            val bytes:ByteArray = md5.digest(str.toByteArray())
+            val stringBuffer:StringBuilder = StringBuilder()
+            for (b in bytes) {
+                val bt:Int = b.toInt() and 0xff
+                if (bt < 16) {
+                    stringBuffer.append(0)
+                }
+                stringBuffer.append(Integer.toHexString(bt))
+            }
+            reStr = stringBuffer.toString()
+        } catch (e: NoSuchAlgorithmException) {
+            e.printStackTrace()
+        }
+
+        return reStr
+    }
+
+    fun strToMd5By16(str: String): String? {
+        var reStr = strToMd5By32(str)
+        if (reStr != null) {
+            reStr = reStr.substring(8, 24)
+        }
+        return reStr
+    }
+}