diff --git a/app/src/core/config.py b/app/src/core/config.py
index ecba6c7..d0a9964 100644
--- a/app/src/core/config.py
+++ b/app/src/core/config.py
@@ -40,7 +40,7 @@ def load_settings() -> Settings:
         bot_parse_mode=os.getenv("BOT_PARSE_MODE", "HTML").strip() or "HTML",
         app_env=os.getenv("APP_ENV", "dev").strip() or "dev",
         log_level=os.getenv("LOG_LEVEL", "INFO").strip().upper() or "INFO",
-        tz=os.getenv("TZ", "Europe/Madrid").strip() or "Europe/Madrid",
+        tz=os.getenv("TZ", "Europe/Minsk").strip() or "Europe/Minsk",
         exchange_enabled=_parse_bool(os.getenv("EXCHANGE_ENABLED", "false")),
         exchange_name=os.getenv("EXCHANGE_NAME", "dzengi").strip() or "dzengi",
         exchange_base_url=os.getenv("EXCHANGE_BASE_URL", "").strip(),
diff --git a/app/src/integrations/exchange/auth.py b/app/src/integrations/exchange/auth.py
new file mode 100644
index 0000000..a0a8efa
--- /dev/null
+++ b/app/src/integrations/exchange/auth.py
@@ -0,0 +1,25 @@
+
+import hmac
+import hashlib
+import time
+
+
+class ExchangeAuth:
+    def __init__(self, api_key: str, api_secret: str):
+        self.api_key = api_key
+        self.api_secret = api_secret.encode()
+
+    def sign(self, query: str) -> str:
+        return hmac.new(self.api_secret, query.encode(), hashlib.sha256).hexdigest()
+
+    def build_headers(self):
+        return {
+            "X-MBX-APIKEY": self.api_key,
+        }
+
+    def build_signed_params(self, params: dict):
+        params["timestamp"] = int(time.time() * 1000)
+        query = "&".join(f"{k}={v}" for k, v in params.items())
+        signature = self.sign(query)
+        params["signature"] = signature
+        return params
diff --git a/app/src/integrations/exchange/private_client.py b/app/src/integrations/exchange/private_client.py
new file mode 100644
index 0000000..adc7982
--- /dev/null
+++ b/app/src/integrations/exchange/private_client.py
@@ -0,0 +1,24 @@
+
+from src.core.config import load_settings
+from src.integrations.exchange.rest_client import ExchangeRestClient
+from src.integrations.exchange.auth import ExchangeAuth
+
+
+class ExchangePrivateClient:
+    def __init__(self):
+        settings = load_settings()
+        self.client = ExchangeRestClient()
+        self.auth = ExchangeAuth(
+            api_key=settings.exchange_api_key,
+            api_secret=settings.exchange_api_secret,
+        )
+
+    def get_account_info(self):
+        params = {}
+        signed = self.auth.build_signed_params(params)
+
+        return self.client.get_json(
+            "/api/v2/account",
+            params=signed,
+            headers=self.auth.build_headers(),
+        )
diff --git a/docs/stages/stage-03-4-auth.md b/docs/stages/stage-03-4-auth.md
new file mode 100644
index 0000000..a109547
--- /dev/null
+++ b/docs/stages/stage-03-4-auth.md
@@ -0,0 +1,10 @@
+
+# Stage 03.4 — Auth
+
+## Что реализовано
+- HMAC подпись
+- headers
+- private client
+
+## Дальше
+Stage 03.5 — account + balances