diff --git a/diy3.py b/diy3.py
index d76aa67..9ed788d 100644
--- a/diy3.py
+++ b/diy3.py
@@ -3,5 +3,5 @@ message = "诺依，周末一起去看动漫展吧！"
 # 请使用索引的知识，取出message所有元素（不用遍历的方式）
 i=0
 while i < len(message):
-    print(message[i])
+    print(message[i])0
     i=i+1
\ No newline at end of file
diff --git a/diy4.py b/diy4.py
new file mode 100644
index 0000000..7d10676
--- /dev/null
+++ b/diy4.py
@@ -0,0 +1,19 @@
+import random
+
+# 私钥
+key = "abcdefgh使用编程实现位移替换加密，制作密码机关真是太好玩了哈哈！"
+# 要加密语句
+message = "诺依，周末一起去看动漫展吧！"
+
+# 请使用私钥key，对message进行加密
+key_message=""
+for i in message:
+    str1=i
+    str2=random.choice(key)
+    str3=random.choice(key)
+    text=str1+str2+str3
+    key_message+=text
+print(key_message)
+
+
+