Trustless deterministic state machine
The invention relates to distributed ledger technologies such as consensus-based blockchains. Computer-implemented methods for a trustless, deterministic state machine are described. The invention is implemented using a blockchain network, which may be, for example, a Bitcoin blockchain. A first transaction to validate is received at a node in a blockchain network. The first transaction includes a first script that, as a result of being executed, causes the node to at least obtain a first set of field values of the first transaction, a second set of field values of a second transaction, and an input. The second transaction is obtained. The second transaction includes a second script that includes a set of rules and, as a result of being executed, causes the node to at least verify that the second script matches a third script embedded in the first set of field values, determine, based at least in part on the second set of field values, a current state, and determine, based at least in part on the current state, the input, and the set of rules, a next state. The first transaction is validated as a result of execution of the first script and the second script.
1. A method comprising:
receiving, at a node in a blockchain network, a first transaction to validate, the first transaction including a first script that, as a result of being executed, causes the node to at least obtain a first set of field values of the first transaction, a second set of field values of a second transaction, and an input;
obtaining the second transaction, the second transaction including a second script that includes a set of rules, the second script, as a result of being executed, causing the node to at least:
verify that the second script matches a third script embedded in the first set of field values;
determine, based at least in part on the second set of field values, a current state;
determine, based at least in part on the current state, the input, and the set of rules, a next state; and
verify that the next state is included in the first set of field values; and
validating the first transaction as a result of execution of the first script and the second script.
2. The method claimed in claim 1 , wherein the second script constrains an identity of a source of the input.
3. The method claimed in claim 1 , further comprising verifying a cryptographic secret of a source of the input.
4. The method claimed in claim 1 , wherein the set of rules is a state-transition matrix.
5. The method claimed in claim 1 , wherein the third script is a locking script that imposes a set of conditions for validation of a future transaction.
6. The method claimed in claim 1 , wherein the second script further causes the node to determine that a termination condition is unfulfilled.
7. The method claimed in claim 1 , wherein the input is embedded in the second set of field values.
8. The method claimed in claim 1 , wherein termination condition is that a digital asset associated with the second transaction is of insufficient size to be transferred.
9. The method claimed in claim 1 , wherein the current state indicates a state of the second transaction.
10. The method claimed in claim 1 , wherein the next state indicates a state of the first transaction upon validation.
11. The method claimed in claim 1 , further comprising:
receiving a third transaction; and
obtaining a fourth script from the first transaction, the fourth script, as a result of being executed, causing the node to determine, based at least in part on the next state, a second input, and the set of rules, another state different from the next state and the current state.
12. The method claimed in claim 1 , wherein the current state and the next state are members of a set of possible states for the first and second transactions.
13. The method claimed in claim 1 , wherein validating the first transaction includes reassociating a digital asset from a first entity to a second entity.
14. A system, comprising:
a processor; and
memory including executable instructions that, as a result of execution by the processor, causes the system to perform the method of claim 1 .
15. A non-transitory computer-readable storage medium having stored thereon executable instructions that, as a result of being executed by a processor of a computer system, cause the computer system to at least perform the method of claim 1 .