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Litecoin: Fix zeitgeist2 attack thanks to Lolcust and ArtForz. This fixes an issue where a 51% attack can change difficulty at will. Go back the full period unless it's the first retarget after genesis.

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coblee 2011-10-09 20:46:21 -10:00 committed by Ross Nicoll
parent 8d52844229
commit 106ecab0e0
1 changed files with 7 additions and 1 deletions
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8
src/pow.cpp
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@ -51,8 +51,14 @@ unsigned int GetNextWorkRequired(const CBlockIndex* pindexLast, const CBlockHead
return pindexLast->nBits;
}
// Litecoin: This fixes an issue where a 51% attack can change difficulty at will.
// Go back the full period unless it's the first retarget after genesis. Code courtesy of Art Forz
int blockstogoback = params.DifficultyAdjustmentInterval()-1;
if ((pindexLast->nHeight+1) != params.DifficultyAdjustmentInterval())
blockstogoback = params.DifficultyAdjustmentInterval();
// Go back by what we want to be 14 days worth of blocks
int nHeightFirst = pindexLast->nHeight - (params.DifficultyAdjustmentInterval()-1);
int nHeightFirst = pindexLast->nHeight - blockstogoback;
assert(nHeightFirst >= 0);
const CBlockIndex* pindexFirst = pindexLast->GetAncestor(nHeightFirst);
assert(pindexFirst);