diff --git a/src/httpaste/backend/file/user.py b/src/httpaste/backend/file/user.py
index 02255b2..72c9256 100644
--- a/src/httpaste/backend/file/user.py
+++ b/src/httpaste/backend/file/user.py
@@ -6,6 +6,12 @@ acting as cells.
 from pathlib import Path
 from ast import literal_eval
 
+COLUMNS = [
+    'sub',
+    'key_hash',
+    'index',
+]
+
 
 def load(
         proto: object,
@@ -22,15 +28,17 @@ def load(
         return None
 
     cells = {}
-    for column in ['key_hash', 'index']:
+    for column in COLUMNS[1:]:
 
         cell = row.joinpath(column)
 
-        if getattr(model_schema, column) == bytes:
-
+        if not cell.exists():
+            cells[column] = None
+        elif getattr(model_schema, column) == bytes:
             cells[column] = cell.read_bytes()
+        elif getattr(model_schema, column) == str:
+            cells[column] = cell.read_text()
         else:
-
             cells[column] = literal_eval(cell.read_text())
 
     return model_class(
@@ -46,7 +54,7 @@ def dump(model: object, path: Path, model_schema: object) -> None:
     row = path.joinpath(model.sub.hex())
     row.mkdir(parents=True, exist_ok=True)
 
-    for column in ['key_hash', 'index']:
+    for column in COLUMNS[1:]:
 
         cell = row.joinpath(column)
 
diff --git a/src/httpaste/model/__init__.py b/src/httpaste/model/__init__.py
index b9d1b4f..7d1280f 100644
--- a/src/httpaste/model/__init__.py
+++ b/src/httpaste/model/__init__.py
@@ -1,6 +1,6 @@
 """Model
 """
-from typing import NamedTuple, Optional, Dict, Union
+from typing import NamedTuple, Optional, Dict, Union, Any, TypedDict
 
 
 class PasteDataSchema:
@@ -98,9 +98,11 @@ class Sub(UserDataSchema.sub):
     """
 
 
-class Index(Dict[PasteId, PasteKey]):
+class Index(TypedDict):
     """User Paste Index
     """
+    auth_expires: int
+    pastes: Dict[str, Dict[str, Any]]
 
 
 class SerializedIndex(UserDataSchema.index):
diff --git a/src/httpaste/model/user.py b/src/httpaste/model/user.py
index 7639127..b925063 100755
--- a/src/httpaste/model/user.py
+++ b/src/httpaste/model/user.py
@@ -2,6 +2,7 @@
 """user model interface
 """
 import json
+from time import time
 from typing import Optional
 
 from httpaste import Config
@@ -34,7 +35,7 @@ class IndexError(Exception):
     """
 
 
-def load(
+def _load(
         proto: User,
         master_key: str,
         backend: object,
@@ -54,16 +55,19 @@ def load(
         return None
 
     try:
-        return User(
-            *model[:-1],
-            Index(**json.loads(decrypt(model.index, master_key, salt, hmac_iter)))
-        )
+        serialized_data = decrypt(model.index, master_key, salt, hmac_iter)
     except DecryptionError as e:
-
         raise IndexError('unable to decrypt user index') from e
+    else:
+        data = json.loads(serialized_data)
+
+    return User(
+        *model[:-1],
+        Index(**data)
+    )
 
 
-def dump(
+def _dump(
         model: User,
         key: MasterKey,
         backend: object,
@@ -77,7 +81,7 @@ def dump(
         :param salt: randomization salt
     """
 
-    if not isinstance(model.index, Index):
+    if model.index is not None and not isinstance(model.index, dict):
 
         raise BaseException('index serialization pre-processing not allowed.')
 
@@ -102,11 +106,13 @@ def load_paste_key(
         :param salt: randomization salt
     """
 
-    for k, v in load(User(sub), key, backend, salt, hmac_iter).index.items():
+    model = _load(User(sub), key, backend, salt, hmac_iter)
+
+    for k, v in model.index.get('pastes').items():
 
         if bytes.fromhex(k) == pid:
 
-            return PasteKey(bytes.fromhex(v))
+            return PasteKey(bytes.fromhex(v.get('key')))
 
     return None
 
@@ -128,12 +134,13 @@ def dump_paste_key(
         :param backend: user model backend
     """
 
-    model = load(User(sub), key, backend, salt, hmac_iter)
+    model = _load(User(sub), key, backend, salt, hmac_iter)
 
-    dump(User(*model[:-1], Index({
-        **model.index,
-        **{pid.hex(): pkey.hex()}
-    })), key, backend, salt, hmac_iter)
+    model.index.setdefault('pastes', {})[pid.hex()] = {
+        'key': pkey.hex()
+    }
+
+    _dump(model, key, backend, salt, hmac_iter)
 
 
 def authenticate(
@@ -154,22 +161,36 @@ def authenticate(
 
     proto = User(sub)
 
+    bogus_decline_msg = 'unable to authenticate'
+
     try:
-        model = load(proto, key, backend, salt, hmac_iter)
+        model = _load(proto, key, backend, salt, hmac_iter)
     except IndexError as e:
-        raise AuthenticationError('you dun goofed')
+        raise AuthenticationError(bogus_decline_msg) from e
 
     if not model:
 
-        model = User(sub, key_hash, Index({}))
-        dump(model, key, backend, salt, hmac_iter)
+        data = {
+            'auth_expires': int(time()) + (1 * 60)
+        }
+
+        model = User(sub, key_hash, Index(data))
+        _dump(model, key, backend, salt, hmac_iter)
     else:
 
         if model.key_hash != key_hash:
 
-            raise AuthenticationError('you dun goofed')
+            raise AuthenticationError(bogus_decline_msg)
 
     return {
         'sub': sub,
         'master_key': key
     }
+
+
+__all__ = [
+    AuthenticationError,
+    load_paste_key,
+    dump_paste_key,
+    authenticate
+]
\ No newline at end of file