Quorum is an open source blockchain protocol specially designed for use in a private blockchain network, where there is only a single member owning all the nodes, or, a consortium blockchain network, where multiple members each own a portion of the network. Quorum is derived from Ethereum by modifying the Geth client.
Some of the key features of Quorum include:
- Privacy via private transactions: members of a Quorum network can send private transactions that are addressed to a subset of nodes, such that the contents of the transaction are not exposed to non-privy members.
- Peer permissioning: a Quorum network can be configured to run in permissioned mode such that all nodes must be explicitly listed in an access control list enforced by all nodes. This prevents foreign nodes from tapping into the network and replicating blocks as is the case in permissionless networks.
- Flexible consensus: described in greater detail later in this post, Quorum supports Raft and Istanbul BFT as valid consensus options. Both support transaction finality (i.e. lack of chain forking) and offer shorter block intervals than proof-of-work.