I could find from online readings that Quorum has a Network Manager component that controls nodes access to network to created permissioned network of nodes. But, I couldn't see explanation on how Network Manager decides which nodes are trustworthy. For example, in the case of Corda network, a certificate is issued to nodes after validation process and it is used for identification nodes during transaction process. Does anyone know how new users are validated and allowed access to network?
so Quorum permissioning implementation v1 is explained here: https://github.com/jpmorganchase/quorum/wiki/Security#network-permissioning, note that permissions system in v1 is node based, meaning this is a per-node whitelist of other accesible nodes.
Next version of permissining will be a deeper implementation allowing more than just a connection white list. It will include node and user level items such as read-only nodes, network white and black list, all known nodes, and ethereum account level permissions such as accounts permitted to transact and so on.