diff --git a/keyserver/src/cron/cron.js b/keyserver/src/cron/cron.js
--- a/keyserver/src/cron/cron.js
+++ b/keyserver/src/cron/cron.js
@@ -16,6 +16,7 @@
   deleteOrphanedSessions,
   deleteOldWebSessions,
 } from '../deleters/session-deleters';
+import { deleteStaleSIWENonceEntries } from '../deleters/siwe-nonce-deleters.js';
 import { deleteInaccessibleThreads } from '../deleters/thread-deleters';
 import { deleteExpiredUpdates } from '../deleters/update-deleters';
 import { deleteUnassignedUploads } from '../deleters/upload-deleters';
@@ -43,6 +44,7 @@
         await deleteOldWebSessions();
         await deleteExpiredUpdates();
         await deleteUnassignedUploads();
+        await deleteStaleSIWENonceEntries();
       } catch (e) {
         console.warn('encountered error while trying to clean database', e);
       }
diff --git a/keyserver/src/deleters/siwe-nonce-deleters.js b/keyserver/src/deleters/siwe-nonce-deleters.js
new file mode 100644
--- /dev/null
+++ b/keyserver/src/deleters/siwe-nonce-deleters.js
@@ -0,0 +1,17 @@
+// @flow
+
+import { dbQuery, SQL } from '../database/database';
+
+// 30 minutes = 30min * 60sec * 1000ms
+export const nonceLifetime = 30 * 60 * 1000;
+
+async function deleteStaleSIWENonceEntries(): Promise<void> {
+  const earliestValidCreationTime = Date.now() - nonceLifetime;
+  const query = SQL`
+    DELETE FROM siwe_nonces
+      WHERE creation_time < ${earliestValidCreationTime}
+  `;
+  await dbQuery(query);
+}
+
+export { deleteStaleSIWENonceEntries };