fix serialization of older certificates

core/src/main/groovy/com/muwire/core/filecert/Certificate.groovy

@@ -115,11 +115,13 @@ class Certificate {
             daos.write(infoHash.getRoot())
             name.write(daos)
             issuer.write(daos)
-            if (comment == null)
-                daos.write((byte) 0)
-            else {
-                daos.write((byte) 1)
-                comment.write(daos)
+            if (version == 2) {
+                if (comment == null)
+                    daos.write((byte) 0)
+                else {
+                    daos.write((byte) 1)
+                    comment.write(daos)
+                }
             }
             daos.write(sig)
             daos.close()
@@ -131,7 +133,7 @@ class Certificate {
     
     @Override
     public int hashCode() {
-        version.hashCode() ^ infoHash.hashCode() ^ timestamp.hashCode() ^ name.hashCode() ^ issuer.hashCode()
+        version.hashCode() ^ infoHash.hashCode() ^ timestamp.hashCode() ^ name.hashCode() ^ issuer.hashCode() ^ Objects.hashCode(comment)
     }
     
     @Override

core/src/main/groovy/com/muwire/core/filecert/CertificateClient.groovy

@@ -73,6 +73,7 @@ class CertificateClient {
                     try {
                         cert = new Certificate(new ByteArrayInputStream(tmp))
                     } catch (IOException | InvalidSignatureException ignore) {
+                        log.log(Level.WARNING, "certificate creation failed",ignore)
                         continue
                     }
                     if (cert.infoHash == e.infoHash)