encrypt recipient message bodies with crypto_box

tests/SMPClient.hs

@@ -61,8 +61,8 @@ cfg =
     { transports = undefined,
       tbqSize = 1,
       msgQueueQuota = 4,
-      queueIdBytes = 12,
-      msgIdBytes = 6,
+      queueIdBytes = 24,
+      msgIdBytes = 24,
       trnSignAlg = C.SignAlg C.SEd448,
       storeLog = Nothing,
       blockSize = 8192,