layout: specification title: May 2018 Hardfork Specification category: spec date: 2018-04-09 activation: 1526400000
When the median time past of the most recent 11 blocks (MTP-11) is greater than or equal to UNIX timestamp 1526400000 Bitcoin Cash will execute a hardfork according to this specification. Starting from the next block these consensus rules changes will take effect:
- Blocksize increase to 32,000,000 bytes
- Re-enabling of several opcodes
The following are not consensus changes, but are recommended changes for Bitcoin Cash implementations:
- Automatic replay protection for future hardforks
- Increase OP_RETURN relay size to 223 total bytes
The blocksize hard capacity limit will be increased to 32MB (32000000 bytes).
Several opcodes will be re-enabled per may-2018-reenabled-opcodes
Automatic Replay Protection
When the median time past of the most recent 11 blocks (MTP-11) is greater than or equal to UNIX timestamp 1542300000 (November 2018 hardfork) Bitcoin Cash full nodes implementing the May 2018 consensus rules SHOULD enforce the following change:
forkid to be equal to 0xFF0001.
ForkIDs beginning with 0xFF will be reserved for future protocol upgrades.
This particular consensus rule MUST NOT be implemented by Bitcoin Cash wallet software.
forkId is defined as per the replay protected sighash specification.