lib

commit c3b2d8ec0f20c7acc12a6bfc3920aa16b80879fb
parent 607a493d7e3066842327338c0dd4f5c45e285477
Author: triesap <tyson@radroots.org>
Date:   Tue, 23 Jun 2026 20:33:44 +0000

simplex: accept future official messages with skipped keys

- continue skipped-key lookup when a retained key has a different message number
- let same-chain future messages decrypt through the current receive chain
- keep replay detection for consumed skipped payloads intact
- cover receiving message three before consuming skipped message one

Diffstat:
M
crates/simplex_smp_crypto/src/ratchet.rs
 | 
14
++++++++++----

1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/crates/simplex_smp_crypto/src/ratchet.rs b/crates/simplex_smp_crypto/src/ratchet.rs
@@ -507,10 +507,7 @@ impl RadrootsSimplexSmpRatchetState {
                 continue;
             };
             if ratchet_header.message_number != skipped.message_number {
-                return Err(RadrootsSimplexSmpCryptoError::RatchetMessageRegression {
-                    received: ratchet_header.message_number,
-                    current: self.receiving_chain_length,
-                });
+                continue;
             }
             let position = self
                 .official_skipped_message_keys
@@ -1191,6 +1188,9 @@ mod tests {
         let second = sender
             .encrypt_official_payload(&shared_secret, b"second", 96)
             .unwrap();
+        let third = sender
+            .encrypt_official_payload(&shared_secret, b"third", 96)
+            .unwrap();
 
         assert_eq!(
             receiver
@@ -1201,6 +1201,12 @@ mod tests {
         assert!(!receiver.is_official_payload_replay(&first).unwrap());
         assert_eq!(
             receiver
+                .decrypt_official_payload(&shared_secret, &third)
+                .unwrap(),
+            b"third"
+        );
+        assert_eq!(
+            receiver
                 .decrypt_official_payload(&shared_secret, &first)
                 .unwrap(),
             b"first"