Generating and validating blockchain transactions

A computer-implemented method of validating blockchain transactions, wherein the method is performed by a node of a blockchain network, wherein the node is configured to execute script written in a high-level (HL) scripting language, wherein the blockchain comprises a first blockchain transaction, wherein the first blockchain transaction comprises a first output, and wherein the method comprises:

• obtaining a second blockchain transaction, wherein the second blockchain transaction comprises a first input comprising a first compact unlocking script (CUS), wherein the first CUS is at least partly written in the HL scripting language and comprises one or more HL functions, wherein when executed, each HL function is configured to perform an operation equivalent to a respective operation performed by one or more low-level (LL) functions of a native, LL scripting language of the blockchain, wherein the first CUS is configured to perform an operation equivalent to a first expanded unlocking script (EUS) written in the LL scripting language and comprising a plurality of LL functions, and wherein the first CUS is smaller in storage size than the first EUS;
• and
• validating the second blockchain transaction, wherein said validating of the second blockchain transaction comprises:
• obtaining the first blockchain transaction, and
• a) replacing the first CUS with the first EUS, and then executing the first EUS together with the first output, wherein a condition of the second transaction being valid is that said execution is successful, or
• b) executing the first CUS together with the first output, wherein a condition of the second transaction being valid is that said execution is successful.

A computer program embodied on non-transitory computer-readable storage media and configured so as, when run on one or more processors, the one or more processors perform a method of validating blockchain transactions, wherein the method is performed by a node of a blockchain network, wherein the node is configured to execute script written in a high-level (HL) scripting language, wherein the blockchain comprises a first blockchain transaction, wherein the first blockchain transaction comprises a first output comprising a first compact locking script (CLS), wherein the first CLS is at least partly written in the HL scripting language and comprises one or more HL functions, wherein when executed, each HL function is configured to perform an operation equivalent to a respective operation performed by one or more low-level (LL) functions of a native, LL scripting language of the blockchain, wherein the first CLS is configured to perform an operation equivalent to a first expanded locking script (ELS) written in the LL scripting language and comprising a plurality of LL functions, and wherein the first CLS is smaller in storage size than the first ELS, and wherein the method is performed by a blockchain node and comprises:

• obtaining a second blockchain transaction, wherein the second blockchain transaction comprises a first input comprising a first unlocking script;
• and
• validating the second blockchain transaction, wherein said validating of the second blockchain transaction comprises:
• obtaining the first blockchain transaction, and
• a) replacing the first CLS with the first ELS, and then executing the first unlocking script together with the first ELS, wherein a condition of the second transaction being valid is that said execution is successful, or
• b) executing the first unlocking script together with the first CLS, wherein a condition of the second transaction being valid is that said execution is successful.