diff --git a/docs/2023-07-01-pastebin.html b/docs/2023-07-01-pastebin.html
index c05241d..5f47e63 100644
--- a/docs/2023-07-01-pastebin.html
+++ b/docs/2023-07-01-pastebin.html
@@ -409,7 +409,7 @@ f2 -r <span class="pl-s"><span class="pl-pds">"</span>{mtime.YYYY}{mtime.MM}{mti
     </h2>
     <div class="highlight highlight-source-shell">
       <pre>grpcurl -proto path/file.proto \
-    -d <span class="pl-s"><span class="pl-pds">'</span>{"key": "value"}<span class="pl-pds">'</span></span> \
+    -d <span class="pl-s"><span class="pl-pds">'</span>{"key": "value", "timestamp": "1997-04-01T00:00:00Z"}<span class="pl-pds">'</span></span> \
     internal-social.zalopay.vn:443 \
     pkg.Service/GetData</pre>
     </div>
diff --git a/docs/2023-08-23-real-world-crypto.html b/docs/2023-08-23-real-world-crypto.html
index f74d86d..e1fd254 100644
--- a/docs/2023-08-23-real-world-crypto.html
+++ b/docs/2023-08-23-real-world-crypto.html
@@ -56,8 +56,16 @@
     </ul>
     <p>
       <strong>MAC</strong> aka Message Authentication Code produce from key,
-      message to authentication tag.
+      message to authentication tag. <strong>HMAC</strong> is MAC using hash.
     </p>
+    <ul>
+      <li>A send B message with MAC (generate from message and A key).</li>
+      <li>
+        B double check message with MAC (generate from receive message and B
+        key).
+      </li>
+      <li>A and B use same key.</li>
+    </ul>
 
     <div>
       Feel free to ask me via
diff --git a/posts/2023-07-01-pastebin.md b/posts/2023-07-01-pastebin.md
index d36b88e..6b0a14d 100644
--- a/posts/2023-07-01-pastebin.md
+++ b/posts/2023-07-01-pastebin.md
@@ -326,7 +326,7 @@ instaloader +login.txt +args.txt +targets.txt
 
 ```sh
 grpcurl -proto path/file.proto \
-    -d '{"key": "value"}' \
+    -d '{"key": "value", "timestamp": "1997-04-01T00:00:00Z"}' \
     internal-social.zalopay.vn:443 \
     pkg.Service/GetData
 ```
diff --git a/posts/2023-08-23-real-world-crypto.md b/posts/2023-08-23-real-world-crypto.md
index 95753e2..58378d1 100644
--- a/posts/2023-08-23-real-world-crypto.md
+++ b/posts/2023-08-23-real-world-crypto.md
@@ -11,4 +11,8 @@ My notes when reading
 - Collision resistance: Can not find 2 input produce same digest.
 
 **MAC** aka Message Authentication Code produce from key, message to
-authentication tag.
+authentication tag. **HMAC** is MAC using hash.
+
+- A send B message with MAC (generate from message and A key).
+- B double check message with MAC (generate from receive message and B key).
+- A and B use same key.