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Consensus support for blinded amounts

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This commit is contained in:
Luke Dashjr 2015-05-20 10:24:16 +00:00 • committed by Matt Corallo
parent b05e98bc9c
commit bf009e4ba1
16 changed files with 177 additions and 98 deletions
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94
src/coins.cpp
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@ -8,6 +8,8 @@
#include <assert.h>
#include <secp256k1.h>
/**
* calculate number of bytes for the bitmask, and its number of non-zero bytes
* each bit in the bitmask represents the availability of one output, but the
@ -250,41 +252,78 @@ const CTxOut &CCoinsViewCache::GetOutputFor(const CTxIn& input) const
return coins->vout[input.prevout.n];
}
CAmount CCoinsViewCache::GetValueIn(const CTransaction& tx) const
{
if (tx.IsCoinBase())
return 0;
CAmount nResult = 0;
for (unsigned int i = 0; i < tx.vin.size(); i++)
{
const CTxOutValue& val = GetOutputFor(tx.vin[i]).nValue;
assert(val.IsAmount());
nResult += val.GetAmount();
}
return nResult;
}
CAmount CCoinsViewCache::GetValueInExcess(const CTransaction& tx) const
{
const CAmount nValueIn = GetValueIn(tx);
const CAmount nValueOut = tx.GetValueOut();
return nValueIn - nValueOut;
}
extern secp256k1_context_t* secp256k1_bitcoin_verify_context;
bool CCoinsViewCache::VerifyAmounts(const CTransaction& tx, const CAmount& excess) const
{
CAmount nInAmount = GetValueIn(tx);
if (nInAmount < excess)
CAmount nPlainAmount = excess;
std::vector<unsigned char> vchData;
std::vector<unsigned char *> vpchCommitsIn, vpchCommitsOut;
bool fNullRangeproof = false;
vchData.resize(CTxOutValue::nCommitmentSize * (tx.vin.size() + tx.vout.size()));
unsigned char *p = vchData.data();
if (!tx.IsCoinBase())
{
for (size_t i = 0; i < tx.vin.size(); ++i)
{
const CTxOutValue& val = GetOutputFor(tx.vin[i]).nValue;
if (val.IsAmount())
nPlainAmount -= val.GetAmount();
else
{
assert(val.vchCommitment.size() == CTxOutValue::nCommitmentSize);
memcpy(p, &val.vchCommitment[0], CTxOutValue::nCommitmentSize);
vpchCommitsIn.push_back(p);
p += CTxOutValue::nCommitmentSize;
}
}
}
for (size_t i = 0; i < tx.vout.size(); ++i)
{
const CTxOutValue& val = tx.vout[i].nValue;
assert(val.vchCommitment.size() == CTxOutValue::nCommitmentSize);
if (val.vchNonceCommitment.size() > CTxOutValue::nCommitmentSize || val.vchRangeproof.size() > 5000)
return false;
if (val.IsAmount())
nPlainAmount += val.GetAmount();
else
{
memcpy(p, &val.vchCommitment[0], CTxOutValue::nCommitmentSize);
vpchCommitsOut.push_back(p);
p += CTxOutValue::nCommitmentSize;
if (val.vchRangeproof.empty())
fNullRangeproof = true;
}
}
// If there are no encrypted input or output values, we can do simple math
if (vpchCommitsIn.size() + vpchCommitsOut.size() == 0)
return (nPlainAmount == 0);
if (!secp256k1_pedersen_verify_tally(secp256k1_bitcoin_verify_context, vpchCommitsIn.data(), vpchCommitsIn.size(), vpchCommitsOut.data(), vpchCommitsOut.size(), nPlainAmount))
return false;
nInAmount -= excess;
return nInAmount == tx.GetValueOut();
// Rangeproof is optional in this case
if ((!vpchCommitsIn.empty()) && vpchCommitsOut.size() == 1 && nPlainAmount <= 0 && fNullRangeproof)
return true;
uint64_t min_value, max_value;
for (size_t i = 0; i < tx.vout.size(); ++i)
{
const CTxOutValue& val = tx.vout[i].nValue;
if (val.IsAmount())
continue;
if (!secp256k1_rangeproof_verify(secp256k1_bitcoin_verify_context, &min_value, &max_value, &val.vchCommitment[0], val.vchRangeproof.data(), val.vchRangeproof.size()))
return false;
}
return true;
}
bool CCoinsViewCache::VerifyAmounts(const CTransaction& tx) const
{
const CAmount excess = GetValueInExcess(tx);
const CAmount& excess = tx.nTxFee;
return VerifyAmounts(tx, excess);
}
@ -322,6 +361,7 @@ double CCoinsViewCache::GetPriority(const CTransaction &tx, int nHeight) const
int nCoinsHeight = coins->nHeight == 0x7fffffff ? nHeight + 1 : coins->nHeight;
if (nCoinsHeight < nHeight + nOffset) {
const CTxOutValue& val = coins->vout[txin.prevout.n].nValue;
// FIXME: This assumes all blinded values are COIN
CAmount nAmount = COIN;
if (val.IsAmount())
nAmount = val.GetAmount();