added a user system

sentence_api/auth.py

@@ -0,0 +1,49 @@
+import hashlib
+import hmac
+import secrets
+from dataclasses import dataclass
+
+
+PBKDF2_ITERATIONS = 120_000
+
+
+@dataclass(frozen=True)
+class AuthenticatedUser:
+    id: str
+    username: str
+    nickname: str
+
+
+def hash_password(password: str) -> str:
+    salt = secrets.token_hex(16)
+    digest = hashlib.pbkdf2_hmac(
+        "sha256",
+        password.encode("utf-8"),
+        salt.encode("ascii"),
+        PBKDF2_ITERATIONS,
+    ).hex()
+    return f"pbkdf2_sha256${PBKDF2_ITERATIONS}${salt}${digest}"
+
+
+def verify_password(password: str, stored: str) -> bool:
+    try:
+        algorithm, iterations, salt, digest = stored.split("$", 3)
+        if algorithm != "pbkdf2_sha256":
+            return False
+        calculated = hashlib.pbkdf2_hmac(
+            "sha256",
+            password.encode("utf-8"),
+            salt.encode("ascii"),
+            int(iterations),
+        ).hex()
+        return hmac.compare_digest(calculated, digest)
+    except (TypeError, ValueError):
+        return False
+
+
+def new_token() -> str:
+    return secrets.token_urlsafe(48)
+
+
+def hash_token(token: str) -> str:
+    return hashlib.sha256(token.encode("utf-8")).hexdigest()