diff --git a/src/chat.rs b/src/chat.rs
index fce3c7d..fdb69ed 100644
--- a/src/chat.rs
+++ b/src/chat.rs
@@ -4,7 +4,7 @@ use colored::{Color, Colorize};
 use crossterm::{cursor::{MoveLeft, MoveRight}, event::{self, Event, KeyCode, KeyModifiers, MouseEventKind}, terminal::{self, disable_raw_mode, enable_raw_mode}};
 use rand::random;
 
-use crate::{util::string_chunks, IP_REGEX};
+use crate::{proto::send_message_auth, util::string_chunks, IP_REGEX};
 
 use super::{proto::read_messages, util::sanitize_text, COLORED_USERNAMES, DATE_REGEX, config::Context, proto::send_message};
 
@@ -269,10 +269,14 @@ fn poll_events(ctx: Arc<Context>) -> Result<(), Box<dyn Error>> {
                             if message.starts_with("/") && !ctx.disable_commands {
                                 on_command(ctx.clone(), &message)?;
                             } else {
-                                let message = ctx.message_format
-                                    .replace("{name}", &ctx.name)
-                                    .replace("{text}", &message);
-                                send_message(&ctx.host, &message)?;
+                                if let Some(password) = &ctx.auth_password {
+                                    send_message_auth(&ctx.host, &ctx.name, password, &message)?;
+                                } else {
+                                    let message = ctx.message_format
+                                        .replace("{name}", &ctx.name)
+                                        .replace("{text}", &message);
+                                    send_message(&ctx.host, &message)?;
+                                }
                             }
                         } else {
                             print_console(
diff --git a/src/config.rs b/src/config.rs
index a98e30b..8eb5e2d 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -169,6 +169,10 @@ pub struct Args {
     /// Configure client
     #[arg(short='C', long)]
     pub configure: bool,
+
+    /// Authentication password
+    #[arg(short='a', long, value_name="PASSWORD")]
+    pub auth: Option<String>,
 }
 
 pub struct Context {
@@ -183,7 +187,8 @@ pub struct Context {
     pub update_time: usize,
     pub max_messages: usize,
     pub enable_ip_viewing: bool,
-    pub scroll: Arc<AtomicUsize>
+    pub scroll: Arc<AtomicUsize>,
+    pub auth_password: Option<String>,
 }
 
 impl Context {
@@ -206,7 +211,8 @@ impl Context {
             update_time: config.update_time,
             max_messages: config.max_messages,
             enable_ip_viewing: args.enable_users_ip_viewing || config.enable_ip_viewing,
-            scroll: Arc::new(AtomicUsize::new(0))
+            scroll: Arc::new(AtomicUsize::new(0)),
+            auth_password: args.auth.clone()
         }
     }
 }
\ No newline at end of file
diff --git a/src/proto.rs b/src/proto.rs
index 9bfd9ca..b314814 100644
--- a/src/proto.rs
+++ b/src/proto.rs
@@ -9,6 +9,40 @@ pub fn send_message(host: &str, message: &str) -> Result<(), Box<dyn Error>> {
     Ok(())
 }
 
+pub fn send_message_auth(host: &str, name: &str, password: &str, message: &str) -> Result<(), Box<dyn Error>> {
+    let mut stream = TcpStream::connect(host)?;
+    stream.write_all(&[0x02])?;
+    stream.write_all(name.as_bytes())?;
+    stream.write_all(&[b'\n'])?;
+    stream.write_all(password.as_bytes())?;
+    stream.write_all(&[b'\n'])?;
+    stream.write_all(message.as_bytes())?;
+    let mut buf = vec![0; 1];
+    stream.read_exact(&mut buf)?;
+    if buf[0] == 0x01 {
+        register_user(host, name, password)?;
+        send_message_auth(host, name, password, message)?
+    } else if buf[0] == 0x02 {
+        println!("Password is incorrect");
+        panic!()
+    }
+    Ok(())
+}
+
+pub fn register_user(host: &str, name: &str, password: &str) -> Result<(), Box<dyn Error>> {
+    let mut stream = TcpStream::connect(host)?;
+    stream.write_all(&[0x00])?;
+    stream.write_all(name.as_bytes())?;
+    stream.write_all(&[b'\n'])?;
+    stream.write_all(password.as_bytes())?;
+    // let mut buf = vec![0; 1];
+    // stream.read(&mut buf)?;
+    // if buf[0] == 0x01 {
+    //     // похуй
+    // }
+    Ok(())
+}
+
 fn skip_null(stream: &mut TcpStream) -> Result<Vec<u8>, Box<dyn Error>> {
     loop {
         let mut buf = vec![0; 1];