The additional features of Ledgerium Core over public Ledgerium transactions are:
Transaction and contract privacy
Multiple voting-based consensus mechanisms
Ledgerium Core currently includes the following components:
Tessera - Transaction Manager
Tessera - Enclave
The Ledgerium Core is a lightweight fork of quorum in order that it can continue to take advantage of the R&D that is taking place within the ever-growing Ethereum & Quorum community. To that end, Ledgerium Core will be updated in line with the future quorum and geth releases.
The Ledgerium Core includes the following modifications to Ethereum:
The consensus is achieved with the Istanbul BFT consensus algorithms instead of using Proof-of-Work.
The block generation logic has been modified to replace the ‘global state root’ check with a new ‘global public state root’.
The State Patricia trie has been split into two: a public state trie and a private state trie.
Block validation logic has been modified to handle ‘Private Transactions’
Transaction creation has been modified to allow for Transaction data to be replaced by encrypted hashes in order to preserve private data where required
Tessera is a fork of JP Morgan tessera and a Java implementation of a general-purpose system for submitting information in a secure way. They are comparable to a network of MTA (Message Transfer Agents) where messages are encrypted with PGP. It is not blockchain-specific, and are potentially applicable in many other types of applications where you want individually-sealed message exchange within a network of counterparties. Tessera modules consist of two sub-modules:
Tessera’s Transaction Manager is responsible for Transaction privacy. It stores and allows access to encrypted transaction data, exchanges encrypted payloads with other participant's Transaction Managers but does not have access to any sensitive private keys. It utilises the Enclave for cryptographic functionality (although the Enclave can optionally be hosted by the Transaction Manager itself.)
The Transaction Manager is restful/stateless and can be load balanced easily.
Distributed Ledger protocols typically leverage cryptographic techniques for transaction authenticity, participant authentication, and historical data preservation (i.e. through a chain of cryptographically hashed data.) In order to achieve a separation of concerns, as well as to provide performance improvements through parallelization of certain crypto-operations, much of the cryptographic work including symmetric key generation and data encryption/decryption is delegated to the Enclave.
The Enclave works hand in hand with the Transaction Manager to strengthen privacy by managing the encryption/decryption in an isolated way. It holds private keys and is essentially a “virtual HSM” isolated from other components.