Computer-implemented systems and methods to enable complex functionality on a blockchain while preserving security-based restrictions on script size and opcode limits
The invention relates to blockchain technologies such as the Bitcoin blockchain. The invention uses a novel technique to decompose the functionality of a blockchain transaction script into several chunks or functional parts, and to use the output of a chunk as the input of the next chunk. Advantageously, this allows the blockchain to be used for ever complex tasks and computations while minimising script size, and also provides a novel architecture for the distributed execution of computational processes. The invention comprises a method of using a plurality of blockchain transactions to execute a computer-implemented task, comprising the steps: using an unlocking script (ULS 1 ) associated with a first input (In 1 ) in a blockchain transaction (Tx 2 ) to present at least one data item to a first locking script (LS 1 ) of another transaction (Tx 1 ) so as to provide a result on a stack; generating a further unlocking script (ULS 2 ) associated with a second input (In 2 ) and comprising the result from the stack; wherein the second input (In 2 ) is provided in a further blockchain transaction (Tx 3 ); and presenting the further unlocking script (ULS 2 ) to a further locking script (LS 2 ) such that the result from the stack is provided as input to the further locking script. Preferably, the locking script (LS 1 ) and further locking script (LS 2 ) are associated with outputs in different blockchain transactions.
1. A system to use a plurality of blockchain transactions to execute a computer-implemented task, the system comprising: one or more processors; and
memory encoding instructions executable by the one or more processors to cause the system to perform operations comprising:
using an unlocking script (ULS 1 ) associated with a first input (In 1 ) in a blockchain transaction (Tx 2 ) to present at least one data item to a first locking script (LS 1 ) of another transaction (Tx 1 ) so as to provide a result on a stack;
generating a further unlocking script (ULS 2 ) associated with a second input (In 2 ) and comprising the result from the stack, wherein the second input (In 2 ) is provided in a further blockchain transaction (Tx 3 ), and wherein the locking script (LS 1 ) and further locking script (LS 2 ) are associated with outputs in different blockchain transactions; and
presenting the further unlocking script (ULS 2 ) to a further locking script (LS 2 ) such that the result from the stack is provided as input to the further locking script.
2. A system according to claim 1 wherein:
the unlocking script (ULS 1 ) and further unlocking script (ULS 2 ) are associated with inputs in different blockchain transactions.
3. A system according claim 1 wherein the operations further comprise:
using the at least one data item in the execution of a calculation or sequence of instructions provided within the first locking script (LS 1 ).
4. A system according to claim 1 wherein the operations further comprise:
using the result provided on the stack in the execution of a calculation or sequence of instructions provided within the further locking script (LS 2 ).
5. A system method according to claim 1 and further comprising the step of wherein the operations further comprise:
obtaining the result from the stack.
6. A system according to claim 1 wherein the operations further comprise:
using a blockchain client to obtain the result from the stack, wherein the blockchain client is a Bitcoin client.
7. A system according to claim 1 wherein the operations further comprise:
validating the blockchain transaction (Tx 2 ) and/or the other transaction (Tx 1 ), and/or further transaction (Tx 3 ) to generate the result on the stack.
8. A system according to claim 1 wherein the operations further comprise:
obtaining the result from the stack and inserting the result into an unlocking script after a return command or instruction.
9. A system according to claim 8 wherein the return command or instruction is a Bitcoin OP_RETURN opcode.
10. A system according to claim 1 wherein:
presenting the further unlocking script (ULS 2 ) to a further locking script (LS 2 ) provides a further result on the stack, or on a different stack.
11. A system according to claim 1 wherein the operations further comprise:
submitting the blockchain transaction (Tx 2 ) and/or other blockchain transaction (Tx 1 ) and/or further transaction (Tx 3 ) to a blockchain network.
12. A system according to claim 1 wherein:
the at least one data item is provided as metadata within the unlocking script (ULS 1 ); and/or
the result is provided as metadata within the further unlocking script (ULS 2 ).
13. A system according to claim 1 wherein the operations further comprise:
performing one or more of the steps of claim 1 more than once.
14. A system according to claim 1 wherein the plurality of blockchain transactions are for a blockchain, and wherein:
the blockchain is a consensus-based, distributed, electronic ledger; and/or
the blockchain is a Bitcoin blockchain; and/or
one, some or all of the plurality of blockchain transactions are Bitcoin transactions; and/or
the method is arranged for execution on the Bitcoin blockchain.