anchor.diff:      end.
   
   block_decrypt(
  -  #params{rekey_interval = RekeyInterval} = Params,
  +  #params{
  +     shared_secret = SharedSecret,
  +     rekey_interval = RekeyInterval} = Params,
     Seq, AeadCipher, Key, IV, Data) ->
       %%
       case crypto:block_decrypt(AeadCipher, Key, IV, Data) of
  
positive.code:                     {Key2B, IV2B} =
                          hmac_key_iv(
                            HmacAlgo, SharedSecret, [R2B, R3A], KeyLen, IVLen),
                      RecvParams = Params#params{key = Key2B, iv = IV2B},
                      %%
                      {SendParams, RecvParams, StartMsg}
              end
  
negative.code:                     {Key2A, IV2A} =
                          hmac_key_iv(
                            HmacAlgo, SharedSecret, [R2A, R3B], KeyLen, IVLen),
                      SendParams =
                          Params#params{
                            shared_secret = SharedSecret,
                            key = Key2A, iv = IV2A},
                      %%
                      StartCleartext = [R2B, R3B, <<RekeyInterval:32>>],
                      StartMsgLen = TagLen + iolist_size(StartCleartext),
  