Make sure "previous counter" is never negative.

10 years ago · c94a7b1eff
parent 4caebdcd06
commit c94a7b1eff
1 changed files with 1 additions and 1 deletions
--- a/libaxolotl/src/main/java/org/whispersystems/libaxolotl/SessionCipher.java
+++ b/libaxolotl/src/main/java/org/whispersystems/libaxolotl/SessionCipher.java
@ -261,7 +261,7 @@ public class SessionCipher {

        sessionState.setRootKey(senderChain.first());
        sessionState.addReceiverChain(theirEphemeral, receiverChain.second());
-        sessionState.setPreviousCounter(sessionState.getSenderChainKey().getIndex()-1);
+        sessionState.setPreviousCounter(Math.max(sessionState.getSenderChainKey().getIndex()-1, 0));
        sessionState.setSenderChain(ourNewEphemeral, senderChain.second());

        return receiverChain.second();