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bulletproofs: multiply points by 8 first thing in verification

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instead of merging that with other scalar multiplications
where possible for speed, since this is not actually safe
This commit is contained in:
moneromooo-monero 2018-09-24 14:01:33 +00:00
parent 8a61f669a9
commit 1dd5c73f62
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GPG key ID: 686F07454D6CEFC3
1 changed files with 17 additions and 15 deletions
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32
src/ringct/bulletproofs.cc
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@ -1068,6 +1068,14 @@ bool bulletproof_VERIFY(const std::vector<const Bulletproof*> &proofs)
CHECK_AND_ASSERT_MES(!(x_ip == rct::zero()), false, "x_ip == 0");
PERF_TIMER_STOP(VERIFY_start);
// pre-multiply some points by 8
rct::keyV proof8_V = proof.V; for (rct::key &k: proof8_V) k = rct::scalarmult8(k);
rct::keyV proof8_L = proof.L; for (rct::key &k: proof8_L) k = rct::scalarmult8(k);
rct::keyV proof8_R = proof.R; for (rct::key &k: proof8_R) k = rct::scalarmult8(k);
rct::key proof8_T1 = rct::scalarmult8(proof.T1);
rct::key proof8_T2 = rct::scalarmult8(proof.T2);
rct::key proof8_S = rct::scalarmult8(proof.S);
PERF_TIMER_START_BP(VERIFY_line_61);
// PAPER LINE 61
sc_muladd(y0.bytes, proof.taux.bytes, weight.bytes, y0.bytes);
@ -1090,26 +1098,22 @@ bool bulletproof_VERIFY(const std::vector<const Bulletproof*> &proofs)
multiexp_data.reserve(proof.V.size());
sc_sub(tmp.bytes, proof.t.bytes, tmp.bytes);
sc_muladd(y1.bytes, tmp.bytes, weight.bytes, y1.bytes);
for (size_t j = 0; j < proof.V.size(); j++)
for (size_t j = 0; j < proof8_V.size(); j++)
{
sc_mul(tmp.bytes, zpow[j+2].bytes, EIGHT.bytes);
multiexp_data.emplace_back(tmp, proof.V[j]);
multiexp_data.emplace_back(zpow[j+2], proof8_V[j]);
}
rct::addKeys(Y2, Y2, rct::scalarmultKey(multiexp(multiexp_data, false), weight));
rct::key weight8;
sc_mul(weight8.bytes, weight.bytes, EIGHT.bytes);
sc_mul(tmp.bytes, x.bytes, weight8.bytes);
rct::addKeys(Y3, Y3, rct::scalarmultKey(proof.T1, tmp));
sc_mul(tmp.bytes, x.bytes, weight.bytes);
rct::addKeys(Y3, Y3, rct::scalarmultKey(proof8_T1, tmp));
rct::key xsq;
sc_mul(xsq.bytes, x.bytes, x.bytes);
sc_mul(tmp.bytes, xsq.bytes, weight8.bytes);
rct::addKeys(Y4, Y4, rct::scalarmultKey(proof.T2, tmp));
sc_mul(tmp.bytes, xsq.bytes, weight.bytes);
rct::addKeys(Y4, Y4, rct::scalarmultKey(proof8_T2, tmp));
PERF_TIMER_STOP(VERIFY_line_61rl_new);
PERF_TIMER_START_BP(VERIFY_line_62);
// PAPER LINE 62
sc_mul(tmp.bytes, x.bytes, EIGHT.bytes);
rct::addKeys(Z0, Z0, rct::scalarmultKey(rct::addKeys(rct::scalarmult8(proof.A), rct::scalarmultKey(proof.S, tmp)), weight));
rct::addKeys(Z0, Z0, rct::scalarmultKey(rct::addKeys(rct::scalarmult8(proof.A), rct::scalarmultKey(proof8_S, x)), weight));
PERF_TIMER_STOP(VERIFY_line_62);
// Compute the number of rounds for the inner product
@ -1192,11 +1196,9 @@ bool bulletproof_VERIFY(const std::vector<const Bulletproof*> &proofs)
for (size_t i = 0; i < rounds; ++i)
{
sc_mul(tmp.bytes, w[i].bytes, w[i].bytes);
sc_mul(tmp.bytes, tmp.bytes, EIGHT.bytes);
multiexp_data.emplace_back(tmp, proof.L[i]);
multiexp_data.emplace_back(tmp, proof8_L[i]);
sc_mul(tmp.bytes, winv[i].bytes, winv[i].bytes);
sc_mul(tmp.bytes, tmp.bytes, EIGHT.bytes);
multiexp_data.emplace_back(tmp, proof.R[i]);
multiexp_data.emplace_back(tmp, proof8_R[i]);
}
rct::key acc = multiexp(multiexp_data, false);
rct::addKeys(Z2, Z2, rct::scalarmultKey(acc, weight));