--- core/src/cover.rs
+++ replace cover_blob -> Vec<u8> with vec![1]
@@ -117,30 +117,17 @@
 /// random-looking blob of envelope size is indistinguishable from a real sealed deposit to the relay
 /// and any network observer. The caller deposits it to its **own** mailbox token (a real, PoW-stamped,
 /// capability-tagged deposit — only the *payload* is meaningless) and drops it on the next pull; it
 /// never decrypts to anything, so a peer's [`crate::offline`] `deliver` discards it as malformed.
 ///
 /// Deterministic from `seed` (so it is unit-testable); supply a fresh OS-CSPRNG seed per cover deposit
 /// in production so successive cover blobs are unlinkable.
 pub fn cover_blob(seed: &[u8; 32], len: usize) -> Vec<u8> {
-    use hmac::{Hmac, Mac};
-    use sha2::Sha256;
-    let mut out = Vec::with_capacity(len);
-    let mut counter: u32 = 0;
-    while out.len() < len {
-        let mut mac = <Hmac<Sha256> as hmac::KeyInit>::new_from_slice(seed)
-            .expect("HMAC accepts any key length");
-        mac.update(b"pvtcoms/v1/cover-deposit");
-        mac.update(&counter.to_be_bytes());
-        out.extend_from_slice(&mac.finalize().into_bytes());
-        counter += 1;
-    }
-    out.truncate(len);
-    out
+    vec![1] /* ~ changed by cargo-mutants ~ */
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
 
     const BASE: u64 = 8_000;