Choosing fork point

Table of Contents

• Overview
• 1. Add block height for Pop Security activation.
• 2. Create a function in the chainparams which detects if the Pop security is enabled.
• 3. Update the block version validation.

Overview

The only way to enable VeriBlock security for already running blockchains is to make a hard fork. For this reason we will provide a height of the fork point.

1. Add block height for Pop Security activation.

https://github.com/VeriBlock/vbk-ri-btc/blob/master/src/consensus/params.h

struct Params

     uint256 nMinimumChainWork;
     uint256 defaultAssumeValid;
+
+    // VeriBlock
+    uint64_t VeriBlockPopSecurityHeight;

Warning

The value must be selected carefully. If current height is X, never set height less or equal to X.

Note

Set VeriBlockPopSecurityHeight equal to 200 in regtest, so that existing tests can be re-used.

2. Create a function in the chainparams which detects if the Pop security is enabled.

https://github.com/VeriBlock/vbk-ri-btc/blob/master/src/chainparams.h

class CChainParams

     const CCheckpointData& Checkpoints() const { return checkpointData; }
     const ChainTxData& TxData() const { return chainTxData; }
+
+    // VeriBlock
+    bool isPopActive(uint64_t height) const {
+        return height >= consensus.VeriBlockPopSecurityHeight;
+    }
+

3. Update the block version validation.

POP_BLOCK_VERSION_BIT should not be set before PoP Activation Height:

https://github.com/VeriBlock/vbk-ri-btc/blob/master/src/validation.cpp

method ContextualCheckBlockHeader

+    // VeriBlock validation
+    if ((block.nVersion & VeriBlock::POP_BLOCK_VERSION_BIT) && !params.isPopActive(nHeight)) {
+    {
+        return state.Invalid(BlockValidationResult::BLOCK_INVALID_HEADER, strprintf("bad-pop-version(0x%08x)", block.nVersion),
+         strprintf("block contains PopData before PopSecurity has been enabled"));
+    }
+
     return true;

Technically, this check is stateless, so can be moved to CheckBlockHeader if wanted.

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