[Cryptography] Standards Trolls: Re: Bitcoin is a disaster.

[Peter Fairbrother]

On 12/01/2021 03:02, Jerry Leichter wrote:

You can come up with ad hoc principles - "a group is legitimate only if 
node N is part of it"; "a group is legitimate only if it contains at 
least 51% of the members who were part of it the last time we had an 
agreement" - but all of these either allow partitioned operation in some 
cases, or fail to allow anyone to proceed in others.

I'm thinking of this as a network of banks. The agreement is about who 
has the money, and how much of it there is.

If my bank is in subset A and I can't do business with a shop whose bank 
is in disjoint subset B, either the shop or me or both is going to 
complain about it.

> 
> BTW, the "node N must be part of any legitimate group" does not really imply centralization - and was used in the original VAXcluster mechanism.  The VAXcluster mechanism require more than half of all nodes that had ever been part of a cluster and had not explicitly announced they were exiting from the set to be present.  This obviously prevent "split brain" partitioned operation; and it obviously could lead to cases in which no cluster could be formed if either enough nodes were down or the partitioning was into multiple too-small partitions.  But an interesting case occurred for a two-node cluster.  If either node was down, the other was blocked, since it alone wasn't a majority.  So there was a hack:  A VAXcluster had access to shared disks.  You could choose a disk to be a "virtual member" of the cluster.  That just meant that when there was an active cluster, a node trying to form a cluster tried to record its identity in a file on the disk.  If it succeeded, it counted as a mem
>   ber of the cluster, giving the node connected a majority.

Never heard of a VAX cluster before, but - isn't that an example of such 
a network actually working?


Peter Fairbrother