fix(security): implement P1 loopback session token, P2 AAD filename binding, and P4 memory zeroization

src/vfs.rs

@@ -14,7 +14,7 @@ use dav_server::{
 };
 use futures_util::stream;
 use tracing::{debug, error, warn};
-use zeroize::Zeroizing;
+use zeroize::{Zeroize, Zeroizing};
 
 use crate::carrier::CarrierFs;
 use crate::crypto::{decrypt_chunk, encrypt_chunk, CHUNK_SIZE};
@@ -200,6 +200,9 @@ impl SanctumFile {
 
         if !is_current {
             self.flush_cached_chunk()?;
+            if let Some((_, ref mut data, _)) = self.cached_chunk {
+                data.zeroize();
+            }
 
             let payload = match self.db.read_chunk(self.node_id, chunk_index).map_err(|e| {
                 error!("Fehler beim Lesen des Chunks #{chunk_index}: {e}");
@@ -236,6 +239,9 @@ impl Drop for SanctumFile {
         if let Err(e) = self.flush_cached_chunk() {
             warn!("Fehler beim automatischen Flush im SanctumFile::drop: {:?}", e);
         }
+        if let Some((_, ref mut data, _)) = self.cached_chunk {
+            data.zeroize();
+        }
         let now = SystemTime::now()
             .duration_since(UNIX_EPOCH)
             .map(|d| d.as_secs())