This proposal replaces several poorly-targeted virtual machine (VM) limits with alternatives which protect against the same malicious cases while significantly increasing the power of the Bitcoin Cash contract system:
- the 520-byte stack element size limit is raised to 10,000 bytes.
- The 201 operation limit is removed.
- A new cumulative hashing limit is introduced, limiting contracts to 660 digest iterations per evaluation.
- A new stack memory usage limit is introduced, limiting contracts to 130,000 bytes of data on the stack.
This proposal intentionally avoids modifying other properties of the current VM:
- The limits on maximum standard input bytecode length (A.K.A.
MAX_TX_IN_SCRIPT_SIG_SIZE– 1,650 bytes), maximum VM bytecode length (A.K.A.
MAX_SCRIPT_SIZE– 10,000 bytes), maximum standard transaction byte-length (A.K.A.
MAX_STANDARD_TX_SIZE– 100,000 bytes) and consensus-maximum transaction byte-length (A.K.A.
MAX_TX_SIZE– 1,000,000 bytes) are not modified.
- The cost and incentives around blockchain “data storage” are not measurably affected.
- The worst-case transaction validation processing and memory requirements of the VM are not measurably affected.
Comments, feedback, and reviews are appreciated, either here or on GitHub issues. Thanks!