mirror of
https://github.com/corda/corda.git
synced 2024-12-27 16:28:56 +00:00
76 lines
3.9 KiB
ReStructuredText
76 lines
3.9 KiB
ReStructuredText
Trade-offs
|
|
==========
|
|
|
|
.. topic:: Summary
|
|
|
|
* *Permissioned networks are better suited for financial use-cases*
|
|
* *Point-to-point communication allows information to be shared need-to-know*
|
|
* *A UTXO model allows for more transactions-per-second*
|
|
|
|
Permissioned vs. permissionless
|
|
-------------------------------
|
|
Traditional blockchain networks are *permissionless*. The parties on the network are anonymous, and can join and
|
|
leave at will.
|
|
|
|
By contrast, Corda networks are *permissioned*. Each party on the network has a known identity that they use when
|
|
communicating with counterparties, and network access is controlled by a doorman. This has several benefits:
|
|
|
|
* Anonymous parties are inappropriate for most scenarios involving regulated financial institutions
|
|
* Knowing the identity of your counterparties allows for off-ledger resolution of conflicts using existing
|
|
legal systems
|
|
* Sybil attacks are averted without the use of expensive mechanisms such as proof-of-work
|
|
|
|
Point-to-point vs. global broadcasts
|
|
------------------------------------
|
|
Traditional blockchain networks broadcast every message to every participant. The reason for this is two-fold:
|
|
|
|
* Counterparty identities are not known, so a message must be sent to every participant to ensure it reaches its
|
|
intended recipient
|
|
* Making every participant aware of every transaction allows the network to prevent double-spends
|
|
|
|
The downside is that all participants see everyone else's data. This is unacceptable for many use-cases.
|
|
|
|
In Corda, each message is instead addressed to a specific counterparty, and is not seen by any uninvolved third
|
|
parties. The developer has full control over what messages are sent, to whom, and in what order. As a result, **data
|
|
is shared on a need-to-know basis only**. To prevent double-spends in this system, we employ notaries as
|
|
an alternative to proof-of-work.
|
|
|
|
Corda also uses several other techniques to maximize privacy on the network:
|
|
|
|
* **Transaction tear-offs**: Transactions are structured in a way that allows them to be digitally signed without
|
|
disclosing the transaction's contents. This is achieved using a data structure called a Merkle tree. You can read
|
|
more about this technique in :doc:`tutorial-tear-offs`.
|
|
* **Key randomisation**: The parties to a transaction are identified only by their public keys, and fresh key pairs are
|
|
generated for each transaction. As a result, an onlooker cannot identify which parties were involved in a given
|
|
transaction.
|
|
|
|
UTXO vs. account model
|
|
----------------------
|
|
Corda uses a *UTXO* (unspent transaction output) model. Each transaction consumes a set of existing states to produce
|
|
a set of new states.
|
|
|
|
The alternative would be an *account* model. In an account model, stateful objects are stored on-ledger, and
|
|
transactions take the form of requests to update the current state of these objects.
|
|
|
|
The main advantage of the UTXO model is that transactions with different inputs can be applied in parallel,
|
|
vastly increasing the network's potential transactions-per-second. In the account model, the number of
|
|
transactions-per-second is limited by the fact that updates to a given object must be applied sequentially.
|
|
|
|
Code-is-law vs. existing legal systems
|
|
--------------------------------------
|
|
Financial institutions need the ability to resolve conflicts using the traditional legal system where required. Corda
|
|
is designed to make this possible by:
|
|
|
|
* Having permissioned networks, meaning that participants are aware of who they are dealing with in every single
|
|
transaction
|
|
* All code contracts should include a ``LegalProseReference`` link to the legal document describing the contract's intended behavior
|
|
which can be relied upon to resolve conflicts
|
|
|
|
Build vs. re-use
|
|
----------------
|
|
Wherever possible, Corda re-uses existing technologies to make the platform more robust platform overall. For
|
|
example, Corda re-uses:
|
|
|
|
* Standard JVM programming languages for the development of CorDapps
|
|
* Existing SQL databases
|
|
* Existing message queue implementations |