diff --git a/keycloak/oauth.py b/keycloak/oauth.py
index cd90d7a..2e6840d 100644
--- a/keycloak/oauth.py
+++ b/keycloak/oauth.py
@@ -3,6 +3,7 @@
 from authlib.common.security import generate_token
 from authlib.integrations.starlette_client import OAuth, StarletteOAuth2App
 from authlib.jose import JWTClaims, JsonWebToken, JsonWebKey
+from authlib.oauth2.rfc7523 import PrivateKeyJWT
 
 from starlette import status
 from starlette.datastructures import URL
@@ -23,7 +24,7 @@ class KeycloakOAuth2:
     def __init__(
         self,
         client_id: str,
-        client_secret: str,
+        client_secret: str | bytes,
         server_metadata_url: str,
         client_kwargs: dict[str, Any],
         base_url: str = "/",
@@ -32,7 +33,26 @@ def __init__(
         self.code_verifier = generate_token(48)
         self._base_url = base_url
         self._logout_page = logout_target
+
         oauth = OAuth()
+
+        # TODO pass properly
+        # Generated via `openssl genrsa - out keypair.pem 2048`
+        with open("keypair.pem", "rb") as f:
+            client_secret = f.read()
+
+        # Generated via `openssl rsa -in keypair.pem -pubout -out publickey.crt`
+        with open("publickey.crt", "r") as f:
+            self.pub = JsonWebKey.import_key(
+                f.read(), {"kty": "RSA", "use": "sig"}
+            ).as_dict()
+
+        # TODO call self.keycloak.load_server_metadata() and get token_endpoint
+        token_endpoint = (
+            "http://localhost:8180/realms/daewy/protocol/openid-connect/token"
+        )
+        auth_method = PrivateKeyJWT(token_endpoint)
+
         oauth.register(
             name="keycloak",
             # client_id and client_secret are created in keycloak
@@ -41,7 +61,10 @@ def __init__(
             server_metadata_url=server_metadata_url,
             client_kwargs=client_kwargs,
             code_challenge_method="S256",
+            client_auth_methods=[auth_method],
+            token_endpoint_auth_method=auth_method.name,
         )
+
         assert isinstance(oauth.keycloak, StarletteOAuth2App)
         self.keycloak = oauth.keycloak
 
@@ -53,6 +76,10 @@ def setup_fastapi_routes(self) -> None:
         self.router.add_api_route("/login", self.login_page)
         self.router.add_api_route("/callback", self.auth)
         self.router.add_api_route("/logout", self.logout)
+        self.router.add_api_route("/certs", self.public_keys)
+
+    async def public_keys(self) -> dict[str, Any]:
+        return {"keys": [self.pub]}
 
     async def login_page(
         self, request: Request, redirect_target: str | None = None