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bulletproofs: scale points by 8 to ensure subgroup validity
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@moneromooo-monero
moneromooo-monero committed Sep 11, 2018
1 parent c83012c commit 044dff5
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Showing 4 changed files with 33 additions and 19 deletions.
2 changes: 1 addition & 1 deletion src/cryptonote_basic/cryptonote_format_utils.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -169,7 +169,7 @@ namespace cryptonote
CHECK_AND_ASSERT_MES(n_amounts == rv.outPk.size(), false, "Internal error filling out V");
rv.p.bulletproofs[0].V.resize(n_amounts);
for (size_t i = 0; i < n_amounts; ++i)
rv.p.bulletproofs[0].V[i] = rv.outPk[i].mask;
rv.p.bulletproofs[0].V[i] = rct::scalarmultKey(rv.outPk[i].mask, rct::INV_EIGHT);
}
}
}
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44 changes: 28 additions & 16 deletions src/ringct/bulletproofs.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -67,6 +67,8 @@ static ge_p3 Hi_p3[maxN*maxM], Gi_p3[maxN*maxM];
static std::shared_ptr<straus_cached_data> straus_HiGi_cache;
static std::shared_ptr<pippenger_cached_data> pippenger_HiGi_cache;
static const rct::key TWO = { {0x02, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 } };
static const rct::key MINUS_ONE = { { 0xec, 0xd3, 0xf5, 0x5c, 0x1a, 0x63, 0x12, 0x58, 0xd6, 0x9c, 0xf7, 0xa2, 0xde, 0xf9, 0xde, 0x14, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10 } };
static const rct::key MINUS_INV_EIGHT = { { 0x74, 0xa4, 0x19, 0x7a, 0xf0, 0x7d, 0x0b, 0xf7, 0x05, 0xc2, 0xda, 0x25, 0x2b, 0x5c, 0x0b, 0x0d, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0a } };
static const rct::keyV oneN = vector_dup(rct::identity(), maxN);
static const rct::keyV twoN = vector_powers(TWO, maxN);
static const rct::key ip12 = inner_product(oneN, twoN);
Expand Down Expand Up @@ -440,6 +442,7 @@ Bulletproof bulletproof_PROVE(const rct::key &sv, const rct::key &gamma)

PERF_TIMER_START_BP(PROVE_v);
rct::addKeys2(V, gamma, sv, rct::H);
V = rct::scalarmultKey(V, INV_EIGHT);
PERF_TIMER_STOP(PROVE_v);

PERF_TIMER_START_BP(PROVE_aLaR);
Expand Down Expand Up @@ -482,13 +485,15 @@ Bulletproof bulletproof_PROVE(const rct::key &sv, const rct::key &gamma)
rct::key ve = vector_exponent(aL, aR);
rct::key A;
rct::addKeys(A, ve, rct::scalarmultBase(alpha));
A = rct::scalarmultKey(A, INV_EIGHT);

// PAPER LINES 40-42
rct::keyV sL = rct::skvGen(N), sR = rct::skvGen(N);
rct::key rho = rct::skGen();
ve = vector_exponent(sL, sR);
rct::key S;
rct::addKeys(S, ve, rct::scalarmultBase(rho));
S = rct::scalarmultKey(S, INV_EIGHT);

// PAPER LINES 43-45
rct::key y = hash_cache_mash(hash_cache, A, S);
Expand Down Expand Up @@ -563,7 +568,9 @@ Bulletproof bulletproof_PROVE(const rct::key &sv, const rct::key &gamma)
rct::key tau1 = rct::skGen(), tau2 = rct::skGen();

rct::key T1 = rct::addKeys(rct::scalarmultH(t1), rct::scalarmultBase(tau1));
T1 = rct::scalarmultKey(T1, INV_EIGHT);
rct::key T2 = rct::addKeys(rct::scalarmultH(t2), rct::scalarmultBase(tau2));
T2 = rct::scalarmultKey(T2, INV_EIGHT);

// PAPER LINES 49-51
rct::key x = hash_cache_mash(hash_cache, z, T1, T2);
Expand Down Expand Up @@ -640,9 +647,11 @@ Bulletproof bulletproof_PROVE(const rct::key &sv, const rct::key &gamma)
L[round] = vector_exponent_custom(slice(Gprime, nprime, Gprime.size()), slice(Hprime, 0, nprime), slice(aprime, 0, nprime), slice(bprime, nprime, bprime.size()));
sc_mul(tmp.bytes, cL.bytes, x_ip.bytes);
rct::addKeys(L[round], L[round], rct::scalarmultH(tmp));
L[round] = rct::scalarmultKey(L[round], INV_EIGHT);
R[round] = vector_exponent_custom(slice(Gprime, 0, nprime), slice(Hprime, nprime, Hprime.size()), slice(aprime, nprime, aprime.size()), slice(bprime, 0, nprime));
sc_mul(tmp.bytes, cR.bytes, x_ip.bytes);
rct::addKeys(R[round], R[round], rct::scalarmultH(tmp));
R[round] = rct::scalarmultKey(R[round], INV_EIGHT);

// PAPER LINES 21-22
w[round] = hash_cache_mash(hash_cache, L[round], R[round]);
Expand Down Expand Up @@ -715,7 +724,10 @@ Bulletproof bulletproof_PROVE(const rct::keyV &sv, const rct::keyV &gamma)

PERF_TIMER_START_BP(PROVE_v);
for (size_t i = 0; i < sv.size(); ++i)
{
rct::addKeys2(V[i], gamma[i], sv[i], rct::H);
V[i] = rct::scalarmultKey(V[i], INV_EIGHT);
}
PERF_TIMER_STOP(PROVE_v);

PERF_TIMER_START_BP(PROVE_aLaR);
Expand Down Expand Up @@ -769,13 +781,15 @@ Bulletproof bulletproof_PROVE(const rct::keyV &sv, const rct::keyV &gamma)
rct::key ve = vector_exponent(aL, aR);
rct::key A;
rct::addKeys(A, ve, rct::scalarmultBase(alpha));
A = rct::scalarmultKey(A, INV_EIGHT);

// PAPER LINES 40-42
rct::keyV sL = rct::skvGen(MN), sR = rct::skvGen(MN);
rct::key rho = rct::skGen();
ve = vector_exponent(sL, sR);
rct::key S;
rct::addKeys(S, ve, rct::scalarmultBase(rho));
S = rct::scalarmultKey(S, INV_EIGHT);

// PAPER LINES 43-45
rct::key y = hash_cache_mash(hash_cache, A, S);
Expand Down Expand Up @@ -835,7 +849,9 @@ Bulletproof bulletproof_PROVE(const rct::keyV &sv, const rct::keyV &gamma)
rct::key tau1 = rct::skGen(), tau2 = rct::skGen();

rct::key T1 = rct::addKeys(rct::scalarmultH(t1), rct::scalarmultBase(tau1));
T1 = rct::scalarmultKey(T1, INV_EIGHT);
rct::key T2 = rct::addKeys(rct::scalarmultH(t2), rct::scalarmultBase(tau2));
T2 = rct::scalarmultKey(T2, INV_EIGHT);

// PAPER LINES 49-51
rct::key x = hash_cache_mash(hash_cache, z, T1, T2);
Expand Down Expand Up @@ -925,9 +941,11 @@ Bulletproof bulletproof_PROVE(const rct::keyV &sv, const rct::keyV &gamma)
L[round] = vector_exponent_custom(slice(Gprime, nprime, Gprime.size()), slice(Hprime, 0, nprime), slice(aprime, 0, nprime), slice(bprime, nprime, bprime.size()));
sc_mul(tmp.bytes, cL.bytes, x_ip.bytes);
rct::addKeys(L[round], L[round], rct::scalarmultH(tmp));
L[round] = rct::scalarmultKey(L[round], INV_EIGHT);
R[round] = vector_exponent_custom(slice(Gprime, 0, nprime), slice(Hprime, nprime, Hprime.size()), slice(aprime, nprime, aprime.size()), slice(bprime, 0, nprime));
sc_mul(tmp.bytes, cR.bytes, x_ip.bytes);
rct::addKeys(R[round], R[round], rct::scalarmultH(tmp));
R[round] = rct::scalarmultKey(R[round], INV_EIGHT);

// PAPER LINES 21-22
w[round] = hash_cache_mash(hash_cache, L[round], R[round]);
Expand Down Expand Up @@ -991,18 +1009,6 @@ bool bulletproof_VERIFY(const std::vector<const Bulletproof*> &proofs)
{
const Bulletproof &proof = *p;

// check subgroup
for (const rct::key &k: proof.V)
CHECK_AND_ASSERT_MES(rct::isInMainSubgroup(k), false, "Input point not in subgroup");
for (const rct::key &k: proof.L)
CHECK_AND_ASSERT_MES(rct::isInMainSubgroup(k), false, "Input point not in subgroup");
for (const rct::key &k: proof.R)
CHECK_AND_ASSERT_MES(rct::isInMainSubgroup(k), false, "Input point not in subgroup");
CHECK_AND_ASSERT_MES(rct::isInMainSubgroup(proof.A), false, "Input point not in subgroup");
CHECK_AND_ASSERT_MES(rct::isInMainSubgroup(proof.S), false, "Input point not in subgroup");
CHECK_AND_ASSERT_MES(rct::isInMainSubgroup(proof.T1), false, "Input point not in subgroup");
CHECK_AND_ASSERT_MES(rct::isInMainSubgroup(proof.T2), false, "Input point not in subgroup");

// check scalar range
CHECK_AND_ASSERT_MES(is_reduced(proof.taux), false, "Input scalar not in range");
CHECK_AND_ASSERT_MES(is_reduced(proof.mu), false, "Input scalar not in range");
Expand Down Expand Up @@ -1078,22 +1084,26 @@ bool bulletproof_VERIFY(const std::vector<const Bulletproof*> &proofs)
sc_muladd(y1.bytes, tmp.bytes, weight.bytes, y1.bytes);
for (size_t j = 0; j < proof.V.size(); j++)
{
multiexp_data.emplace_back(zpow[j+2], proof.V[j]);
sc_mul(tmp.bytes, zpow[j+2].bytes, EIGHT.bytes);
multiexp_data.emplace_back(tmp, proof.V[j]);
}
rct::key temp = multiexp(multiexp_data, false);

rct::addKeys(Y2, Y2, rct::scalarmultKey(temp, weight));
sc_mul(tmp.bytes, x.bytes, weight.bytes);
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));
rct::key xsq;
sc_mul(xsq.bytes, x.bytes, x.bytes);
sc_mul(tmp.bytes, xsq.bytes, weight.bytes);
sc_mul(tmp.bytes, xsq.bytes, weight8.bytes);
rct::addKeys(Y4, Y4, rct::scalarmultKey(proof.T2, tmp));
PERF_TIMER_STOP(VERIFY_line_61rl_new);

PERF_TIMER_START_BP(VERIFY_line_62);
// PAPER LINE 62
rct::addKeys(Z0, Z0, rct::scalarmultKey(rct::addKeys(proof.A, rct::scalarmultKey(proof.S, x)), weight));
sc_mul(tmp.bytes, x.bytes, EIGHT.bytes);
rct::addKeys(Z0, Z0, rct::scalarmultKey(rct::addKeys(rct::scalarmultKey(proof.A, EIGHT), rct::scalarmultKey(proof.S, tmp)), weight));
PERF_TIMER_STOP(VERIFY_line_62);

// Compute the number of rounds for the inner product
Expand Down Expand Up @@ -1176,8 +1186,10 @@ 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]);
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]);
}
rct::key acc = multiexp(multiexp_data, false);
Expand Down
2 changes: 2 additions & 0 deletions src/ringct/rctOps.h
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Original file line number Diff line number Diff line change
Expand Up @@ -63,6 +63,8 @@ namespace rct {
static const key I = { {0x01, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 } };
static const key L = { {0xed, 0xd3, 0xf5, 0x5c, 0x1a, 0x63, 0x12, 0x58, 0xd6, 0x9c, 0xf7, 0xa2, 0xde, 0xf9, 0xde, 0x14, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10 } };
static const key G = { {0x58, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66 } };
static const key EIGHT = { {0x08, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 } };
static const key INV_EIGHT = { { 0x79, 0x2f, 0xdc, 0xe2, 0x29, 0xe5, 0x06, 0x61, 0xd0, 0xda, 0x1c, 0x7d, 0xb3, 0x9d, 0xd3, 0x07, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x06 } };

//Creates a zero scalar
inline key zero() { return Z; }
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4 changes: 2 additions & 2 deletions src/ringct/rctSigs.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -768,7 +768,7 @@ namespace rct {
#endif
for (i = 0; i < outamounts.size(); ++i)
{
rv.outPk[i].mask = C[i];
rv.outPk[i].mask = rct::scalarmultKey(C[i], EIGHT);
outSk[i].mask = masks[i];
}
}
Expand All @@ -788,7 +788,7 @@ namespace rct {
#endif
for (i = 0; i < batch_size; ++i)
{
rv.outPk[i + amounts_proved].mask = C[i];
rv.outPk[i + amounts_proved].mask = rct::scalarmultKey(C[i], EIGHT);
outSk[i + amounts_proved].mask = masks[i];
}
amounts_proved += batch_size;
Expand Down

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