MagCarta
MagCarta is a Turing Complete smart contract description language. MagCarta schedules and coordinates Prometh applications on the Leviatom network. MagCarta can be roughly regarded as a Bash script in Linux environment, which implements the most basic program logic and further invokes other Linux programs for more complex functionalities. Moreover, MagCarta distributes rewards to programs, computations and data providers. Each MagCarta smart contract is defined by a set of declarations, which specifies the compute, programs, and data that will be referenced by the smart contract codes. Transactions are also defined to represent the input data for the contract.
The COMPUTE_DECLARATION specifies the kinds of Leviatom nodes to run the target application. Line 1 declares the name of the type of computes. Started from Line 2, a set of <KEY,VALUE> pairs specify the properties of the desired computes.
A few $PROPERTY_KEY are defined to satisfy the most common usage scenarios.
TRUST_VALUE identifies the trustworthiness of the identified nodes. It is the basic value propagated by the Leviatom network. TRUST_VALUE represents the target node’s cost for implementing a“malicious collective”, i.e. the least number of other nodes that the target has to bribe in order to “tell a lie”.
SOFTWARE_STACK specifies the desirable software to run on the identified nodes. This property help eliminating or selecting the particular nodes who are installed with target software applications. It allows the contract to further identify the security or functional properties of the target node’s execution environment. The values of this property are usually specified by the PROGRAM_DECLARATION, introduced next.
DATA_STORE specifies the data ownership of the target node. This property allows the contract to identify only the nodes possessing particular data. It is especially useful for the applications who need to access particular data, regardless of other properties of the target nodes. It allows MagCarta to schedule particular application to the node possessing the data, and achieve trusted local computation, instead of requiring the data own to share the data, in order to achieve multi-party computation.
PROGRAM_DECLARATION identifies the target application to run on Leviatom nodes. Line 1 defines the name of the target type of applications. Started from Line 2, a set of <KEY,VALUE> pairs specify the properties of the desired programs.
A few $PROPERTY_KEY are defined to satisfy the most common usage scenarios.
ID identified a unique name of the target program. This is the fastest way to locate an application from Prometh’s application store.
VERIFIED_DESCRIPTION defines the verification entities for the target application. This can be a set of <KEY, VALUE> pairs, specifying a particular property (identified by KEY) is automatically verified and signed by a third-party application (identified by VALUE). As the verification applications themselves need verification, the VALUE may reference to another PROGRAME_DECLARATION. This referencing process may iterate until a minimum set of software building tools are identified. For the correctness of these tools, formal verifications are applied.
DATA_DECLARATION identifies the properties of the target data to be possessed by the target node. Line 1 defines the name of the target type of data. Started from Line 2, a set of <KEY,VALUE> pairs specify the properties of the desired dataset.
ID identified a unique name of the target program. This is the fastest way to locate an application from Prometh’s application store.
VERIFIED_DESCRIPTION defines the verification entities for the target data. This can be a set of <KEY, VALUE> pairs, specifying a particular property (identified by KEY) is automatically verified and signed by a third-party application (identified by VALUE). As the verification applications themselves need verification, the VALUE may reference to another PROGRAME_DECLARATION. This referencing process may iterate until a minimum set of software building tools are identified. For the correctness of these tools, formal verifications are applied.
TX_DECLARATION identifies the format of the transactions that the target contract can process. A transaction transmits the input value to a contract. In MagCarta, Leviatom nodes, Prometh applications, and dataset, can all be sent as transactions to a target contract.
The core of MagCarta Smart Contract is a new operation: the consensus call. It initiates the Prometh program scheduling process among predefined Leviatom nodes. In MagCarta, the type of programs, the type of target nodes, and the type of strategy for reaching consensus and distributing rewards, can all be defined by developers.
The consensus call will distribute the Prometh programs identified in the PROGRAM_SET parameter to the Leviatom nodes defined by the COMPUTE_SET parameter. The STRATEGY_SET allows developers to specify how the different copies of programs reach a consensus, and how to pay the Leviatom nodes and the Prometh application providers.
The consensus call allows MagCarta contract developers to delegate complex business logic to native applications running on general-purpose computing platforms, such as PCs, enterprise servers, mobile phones or IoT devices. For these delegated tasks, Prometh guarantees the genuine implementation of their behaviours, and Leviatom achieves the correct execution. The consensus call further implements the strategy for trusting the delegated executions’ results.
Meanwhile, Prometh programs can also implement the data collection logic, with the trustworthy nodes selected by the Leviatom network, the data collector’s behaviours will be genuinely executed. This guarantees the trustworthiness of the data before they are submitted to the blockchain. More detailed designs and implementations will be given in a separated technical whitepaper.
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