diff --git a/selfprivacy_api/actions/api_tokens.py b/selfprivacy_api/actions/api_tokens.py
index 394d3d98..3b180e84 100644
--- a/selfprivacy_api/actions/api_tokens.py
+++ b/selfprivacy_api/actions/api_tokens.py
@@ -11,6 +11,7 @@ from selfprivacy_api.repositories.tokens.exceptions import (
     TokenNotFound,
     RecoveryKeyNotFound,
     InvalidMnemonic,
+    NewDeviceKeyNotFound,
 )
 
 TOKEN_REPO = JsonTokensRepository()
@@ -142,3 +143,15 @@ def get_new_device_auth_token() -> str:
     """
     key = TOKEN_REPO.get_new_device_key()
     return Mnemonic(language="english").to_mnemonic(bytes.fromhex(key.key))
+
+
+def use_new_device_auth_token(mnemonic_phrase, name) -> str:
+    """Use the new device auth token by converting the mnemonic string to a byte array.
+    If the mnemonic phrase is valid then generate a device token and return it.
+    New device auth token must be deleted.
+    """
+    try:
+        token = TOKEN_REPO.use_mnemonic_new_device_key(mnemonic_phrase, name)
+        return token.token
+    except (NewDeviceKeyNotFound, InvalidMnemonic):
+        return None
diff --git a/selfprivacy_api/graphql/mutations/api_mutations.py b/selfprivacy_api/graphql/mutations/api_mutations.py
index 45961c81..0c413fbc 100644
--- a/selfprivacy_api/graphql/mutations/api_mutations.py
+++ b/selfprivacy_api/graphql/mutations/api_mutations.py
@@ -15,6 +15,7 @@ from selfprivacy_api.actions.api_tokens import (
     refresh_api_token,
     delete_new_device_auth_token,
     get_new_device_auth_token,
+    use_new_device_auth_token,
 )
 from selfprivacy_api.graphql import IsAuthenticated
 from selfprivacy_api.graphql.mutations.mutation_interface import (
@@ -22,9 +23,6 @@ from selfprivacy_api.graphql.mutations.mutation_interface import (
     MutationReturnInterface,
 )
 
-from selfprivacy_api.utils.auth import (
-    use_new_device_auth_token,
-)
 
 from selfprivacy_api.repositories.tokens.json_tokens_repository import (
     JsonTokensRepository,
diff --git a/selfprivacy_api/rest/api_auth.py b/selfprivacy_api/rest/api_auth.py
index ab96bee5..275dac36 100644
--- a/selfprivacy_api/rest/api_auth.py
+++ b/selfprivacy_api/rest/api_auth.py
@@ -15,13 +15,11 @@ from selfprivacy_api.actions.api_tokens import (
     use_mnemonic_recovery_token,
     delete_new_device_auth_token,
     get_new_device_auth_token,
+    use_new_device_auth_token,
 )
 
 from selfprivacy_api.dependencies import TokenHeader, get_token_header
 
-from selfprivacy_api.utils.auth import (
-    use_new_device_auth_token,
-)
 
 router = APIRouter(
     prefix="/auth",
diff --git a/selfprivacy_api/utils/auth.py b/selfprivacy_api/utils/auth.py
index 11836b17..53dffd7e 100644
--- a/selfprivacy_api/utils/auth.py
+++ b/selfprivacy_api/utils/auth.py
@@ -200,24 +200,3 @@ def _get_new_device_auth_token():
         if datetime.now() > expiration:
             return None
         return new_device["token"]
-
-
-def use_new_device_auth_token(mnemonic_phrase, name):
-    """Use the new device auth token by converting the mnemonic string to a byte array.
-    If the mnemonic phrase is valid then generate a device token and return it.
-    New device auth token must be deleted.
-    """
-    token_str = _get_new_device_auth_token()
-    if token_str is None:
-        return None
-    token = bytes.fromhex(token_str)
-    if not Mnemonic(language="english").check(mnemonic_phrase):
-        return None
-    phrase_bytes = Mnemonic(language="english").to_entropy(mnemonic_phrase)
-    if phrase_bytes != token:
-        return None
-    token = create_token(name)
-    with WriteUserData(UserDataFiles.TOKENS) as tokens:
-        if "new_device" in tokens:
-            del tokens["new_device"]
-    return token