Core Concepts

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Statechain

A statechain is a protocol that enables off-chain transfers of ownership for blockchain assets. It allows users to transfer control of a UTXO multiple times without creating on-chain transactions, using cryptographic signatures facilitated by a group of entities. This approach aims to improve transaction speed, privacy, and scalability while maintaining the security of the underlying blockchain.

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Spark Entity (SE)

The group of operators that run a Spark. They are responsible for performing the operations necessary for signing and forgetting past keys.

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Spark Operator (SO)

One of the operators within the SE. All or a threshold of operators are used to aid in the transfer of off-chain UTXOs.

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Spark Service Provider (SSP)

A service provider who facilitates efficient deposits/withdrawals to/from Spark. Any number of SSPs can exist within a single Spark. Either SSPs or another entity can additionally optionally serve as Lightning providers to enable Lightning transactions for users within Spark.

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Branches and Leaves

Leaves are terminal transactions of the tree that are owned by an individual user.

Branches are all transactions of the tree that are not leaf transactions. These are nearly identical to leaf transactions, except they do not have timelocks and can only be spent by the sum of the keys of the leaves under them.

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Exit Transaction

A signed Bitcoin transaction that sends funds from Spark to the user. This serves as the unilateral exit mechanism, enabling any user to withdraw funds from Spark without cooperation by broadcasting the exit transaction and its parents.

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Atomic Swap

Exchanging two secrets A and B trustlessly for each other such that either both parties involved know both A and B or neither know both A and B.