| rskip | title | created | author | purpose | layer | complexity | status | description |
|---|---|---|---|---|---|---|---|---|
454 |
Support bitcoin blocks with chain work up to 32 unsigned bytes |
25-Oct-24 |
NC |
Sca |
Core |
1 |
Draft |
| RSKIP | 454 |
|---|---|
| Title | Support bitcoin blocks with chain work up to 32 unsigned bytes |
| Created | 25-Oct-24 |
| Author | NC |
| Purpose | Sca |
| Layer | Core |
| Complexity | 1 |
| Status | Draft |
This RSKIP proposes enabling Rootstock to accept Bitcoin blocks with chain work up to 32 unsigned bytes (256 bits). This change is necessary to ensure the bridge can process Bitcoin blocks with chain work values that exceed the current 12 unsigned bytes limit (96 bits).
Before RSKIP434 the chain work was even lower (12 signed bytes, 1 bit reserved for the sign and 95 bits used to store the chain work value). This 95 bits limit chain work got surpassed by the block #849,138 causing Rootstock nodes to be unable to process Bitcoin blocks, resulting in a Rootstock peg-in / peg-out service outage.[2]
Therefore, in order to guarantee the future stability of the Rootstock network, it is necessary to increase the chain work limit before the chain work value exceed the current 12 unsigned bytes limit.
Ensure Rootstock nodes stability and prevent future disruptions in the Rootstock network caused by the inability to process Bitcoin blocks with chain work values that exceed the current 12 unsigned bytes limit.
- Store chain work values of Bitcoin block headers using 32 unsigned bytes. This implies that after this RSKIP gets activated, stored blocks in Rootstock nodes' storage will go from 96 bytes to 116 bytes in size. 32 bytes will be used to store the chain work value and the remaining 84 bytes will be used to store the rest of the block header.
- Add support to serialize and deserialize chain work values up to 32 unsigned bytes of Bitcoin block headers stored in the Rootstock Bridge.
- Deprecate binary checkpoint support in favor of adding support for the textual checkpoint format. Checkpoints with 32 unsigned bytes chain work must be in textual format to be processed, as the binary checkpoint format does not support mixing Bitcoin header sizes.
This change is a hard fork, as it increases the size for storing block headers by 20 bytes to support larger chain work values (up to 32 unsigned bytes). Therefore, all nodes must be updated.
Given the continued increase in Bitcoin's network difficulty, the chain work value of Bitcoin blocks will continue to grow and will inevitably exceed 96 bits, which would again cause an overflow issue. Therefore, this long-term solution is needed to prevent future disruption in the Rootstock network. The max chain work value supported now will be 2^256 - 1 or ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff.
[1] Support bitcoin blocks with chain work up to 32 unsigned bytes RSKIP434
[2] Rootstock incident report https://blog.rootstock.io/noticia/incident-report-rootstock-peg-in-peg-out-service-outage-on-june-24th/
[3] Bitcoin block #849,138 https://mempool.space/block/00000000000000000002717c41c14b7865e24af838dbc374fc1952f9cbf7a2ff
[4] BitcoinJ long-term solution bitcoinj/bitcoinj#3425, bitcoinj/bitcoinj#3426, bitcoinj/bitcoinj#3427, bitcoinj/bitcoinj#3428
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