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ringct: add bos coster multiexp
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@moneromooo-monero
moneromooo-monero committed Sep 11, 2018
1 parent e9164bb commit 9ff6e6a
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Showing 4 changed files with 455 additions and 51 deletions.
2 changes: 2 additions & 0 deletions src/ringct/CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -30,11 +30,13 @@ set(ringct_basic_sources
rctOps.cpp
rctTypes.cpp
rctCryptoOps.c
multiexp.cc
bulletproofs.cc)

set(ringct_basic_private_headers
rctOps.h
rctTypes.h
multiexp.h
bulletproofs.h)

monero_private_headers(ringct_basic
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205 changes: 154 additions & 51 deletions src/ringct/bulletproofs.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -38,6 +38,7 @@ extern "C"
#include "crypto/crypto-ops.h"
}
#include "rctOps.h"
#include "multiexp.h"
#include "bulletproofs.h"

#undef MONERO_DEFAULT_LOG_CATEGORY
Expand All @@ -58,6 +59,7 @@ static rct::key inner_product(const rct::keyV &a, const rct::keyV &b);
static constexpr size_t maxN = 64;
static constexpr size_t maxM = 16;
static rct::key Hi[maxN*maxM], Gi[maxN*maxM];
static ge_p3 Hi_p3[maxN*maxM], Gi_p3[maxN*maxM];
static ge_dsmp Gprecomp[maxN*maxM], Hprecomp[maxN*maxM];
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::keyV oneN = vector_dup(rct::identity(), maxN);
Expand Down Expand Up @@ -110,9 +112,12 @@ static void init_exponents()
{
Hi[i] = get_exponent(rct::H, i * 2);
rct::precomp(Hprecomp[i], Hi[i]);
CHECK_AND_ASSERT_THROW_MES(ge_frombytes_vartime(&Hi_p3[i], Hi[i].bytes) == 0, "ge_frombytes_vartime failed");
Gi[i] = get_exponent(rct::H, i * 2 + 1);
rct::precomp(Gprecomp[i], Gi[i]);
CHECK_AND_ASSERT_THROW_MES(ge_frombytes_vartime(&Gi_p3[i], Gi[i].bytes) == 0, "ge_frombytes_vartime failed");
}
MINFO("cache size: " << (sizeof(Hi)+sizeof(Hprecomp)+sizeof(Hi_p3))*2/1024 << " kB");
init_done = true;
}

Expand All @@ -121,6 +126,26 @@ static rct::key vector_exponent(const rct::keyV &a, const rct::keyV &b)
{
CHECK_AND_ASSERT_THROW_MES(a.size() == b.size(), "Incompatible sizes of a and b");
CHECK_AND_ASSERT_THROW_MES(a.size() <= maxN*maxM, "Incompatible sizes of a and maxN");
#if 1
std::vector<MultiexpData> multiexp_data;
multiexp_data.reserve(a.size()*2);
for (size_t i = 0; i < a.size(); ++i)
{
if (!(a[i] == rct::zero()))
{
multiexp_data.resize(multiexp_data.size() + 1);
multiexp_data.back().scalar = a[i];
multiexp_data.back().point = Gi_p3[i];
}
if (!(b[i] == rct::zero()))
{
multiexp_data.resize(multiexp_data.size() + 1);
multiexp_data.back().scalar = b[i];
multiexp_data.back().point = Hi_p3[i];
}
}
return bos_coster_heap_conv_robust(multiexp_data);
#else
ge_p3 res_p3 = ge_p3_identity;
for (size_t i = 0; i < a.size(); ++i)
{
Expand All @@ -129,6 +154,7 @@ static rct::key vector_exponent(const rct::keyV &a, const rct::keyV &b)
rct::key res;
ge_p3_tobytes(res.bytes, &res_p3);
return res;
#endif
}

/* Compute a custom vector-scalar commitment */
Expand All @@ -138,6 +164,26 @@ static rct::key vector_exponent_custom(const rct::keyV &A, const rct::keyV &B, c
CHECK_AND_ASSERT_THROW_MES(a.size() == b.size(), "Incompatible sizes of a and b");
CHECK_AND_ASSERT_THROW_MES(a.size() == A.size(), "Incompatible sizes of a and A");
CHECK_AND_ASSERT_THROW_MES(a.size() <= maxN*maxM, "Incompatible sizes of a and maxN");
#if 1
std::vector<MultiexpData> multiexp_data;
multiexp_data.reserve(a.size()*2);
for (size_t i = 0; i < a.size(); ++i)
{
if (!(a[i] == rct::zero()))
{
multiexp_data.resize(multiexp_data.size() + 1);
multiexp_data.back().scalar = a[i];
CHECK_AND_ASSERT_THROW_MES(ge_frombytes_vartime(&multiexp_data.back().point, A[i].bytes) == 0, "ge_frombytes_vartime failed");
}
if (!(b[i] == rct::zero()))
{
multiexp_data.resize(multiexp_data.size() + 1);
multiexp_data.back().scalar = b[i];
CHECK_AND_ASSERT_THROW_MES(ge_frombytes_vartime(&multiexp_data.back().point, B[i].bytes) == 0, "ge_frombytes_vartime failed");
}
}
return bos_coster_heap_conv_robust(multiexp_data);
#else
ge_p3 res_p3 = ge_p3_identity;
for (size_t i = 0; i < a.size(); ++i)
{
Expand Down Expand Up @@ -174,6 +220,7 @@ static rct::key vector_exponent_custom(const rct::keyV &A, const rct::keyV &B, c
rct::key res;
ge_p3_tobytes(res.bytes, &res_p3);
return res;
#endif
}

/* Given a scalar, construct a vector of powers */
Expand Down Expand Up @@ -924,7 +971,7 @@ bool bulletproof_VERIFY(const Bulletproof &proof)

PERF_TIMER_START_BP(VERIFY_line_61);
// PAPER LINE 61
rct::key L61Left;
rct::key L61Left, L61Right;
rct::addKeys2(L61Left, proof.taux, proof.t, rct::H);

const rct::keyV zpow = vector_powers(z, M+3);
Expand All @@ -939,36 +986,61 @@ bool bulletproof_VERIFY(const Bulletproof &proof)
}
PERF_TIMER_STOP(VERIFY_line_61);

PERF_TIMER_START_BP(VERIFY_line_61rl);
sc_muladd(tmp.bytes, z.bytes, ip1y.bytes, k.bytes);
rct::key L61Right = rct::scalarmultKey(rct::H, tmp);
ge_p3 L61Right_p3;
CHECK_AND_ASSERT_THROW_MES(ge_frombytes_vartime(&L61Right_p3, L61Right.bytes) == 0, "ge_frombytes_vartime failed");
for (size_t j = 0; j+1 < proof.V.size(); j += 2)
// multiexp is slower for small numbers of calcs
if (M >= 16)
{
CHECK_AND_ASSERT_MES(j+2+1 < zpow.size(), false, "invalid zpow index");
ge_dsmp precomp0, precomp1;
rct::precomp(precomp0, j < proof.V.size() ? proof.V[j] : rct::identity());
rct::precomp(precomp1, j+1 < proof.V.size() ? proof.V[j+1] : rct::identity());
rct::addKeys3acc_p3(&L61Right_p3, zpow[j+2], precomp0, zpow[j+2+1], precomp1);
PERF_TIMER_START_BP(VERIFY_line_61rl_new);
sc_muladd(tmp.bytes, z.bytes, ip1y.bytes, k.bytes);
std::vector<MultiexpData> multiexp_data;
multiexp_data.reserve(3+M);
multiexp_data.push_back({tmp, rct::H});
for (size_t j = 0; j < M; j++)
{
if (!(zpow[j+2] == rct::zero()))
multiexp_data.push_back({zpow[j+2], j < proof.V.size() ? proof.V[j] : rct::identity()});
}
if (!(x == rct::zero()))
multiexp_data.push_back({x, proof.T1});
rct::key xsq;
sc_mul(xsq.bytes, x.bytes, x.bytes);
if (!(xsq == rct::zero()))
multiexp_data.push_back({xsq, proof.T2});
L61Right = bos_coster_heap_conv_robust(multiexp_data);
PERF_TIMER_STOP(VERIFY_line_61rl_new);
}
for (size_t j = proof.V.size() & 0xfffffffe; j < M; j++)
else
{
CHECK_AND_ASSERT_MES(j+2 < zpow.size(), false, "invalid zpow index");
// faster equivalent to:
// tmp = rct::scalarmultKey(j < proof.V.size() ? proof.V[j] : rct::identity(), zpow[j+2]);
// rct::addKeys(L61Right, L61Right, tmp);
if (j < proof.V.size())
addKeys_acc_p3(&L61Right_p3, zpow[j+2], proof.V[j]);
}
PERF_TIMER_START_BP(VERIFY_line_61rl_old);
sc_muladd(tmp.bytes, z.bytes, ip1y.bytes, k.bytes);
L61Right = rct::scalarmultKey(rct::H, tmp);
ge_p3 L61Right_p3;
CHECK_AND_ASSERT_THROW_MES(ge_frombytes_vartime(&L61Right_p3, L61Right.bytes) == 0, "ge_frombytes_vartime failed");
for (size_t j = 0; j+1 < proof.V.size(); j += 2)
{
CHECK_AND_ASSERT_MES(j+2+1 < zpow.size(), false, "invalid zpow index");
ge_dsmp precomp0, precomp1;
rct::precomp(precomp0, j < proof.V.size() ? proof.V[j] : rct::identity());
rct::precomp(precomp1, j+1 < proof.V.size() ? proof.V[j+1] : rct::identity());
rct::addKeys3acc_p3(&L61Right_p3, zpow[j+2], precomp0, zpow[j+2+1], precomp1);
}
for (size_t j = proof.V.size() & 0xfffffffe; j < M; j++)
{
CHECK_AND_ASSERT_MES(j+2 < zpow.size(), false, "invalid zpow index");
// faster equivalent to:
// tmp = rct::scalarmultKey(j < proof.V.size() ? proof.V[j] : rct::identity(), zpow[j+2]);
// rct::addKeys(L61Right, L61Right, tmp);
if (j < proof.V.size())
addKeys_acc_p3(&L61Right_p3, zpow[j+2], proof.V[j]);
}

addKeys_acc_p3(&L61Right_p3, x, proof.T1);
addKeys_acc_p3(&L61Right_p3, x, proof.T1);

rct::key xsq;
sc_mul(xsq.bytes, x.bytes, x.bytes);
addKeys_acc_p3(&L61Right_p3, xsq, proof.T2);
ge_p3_tobytes(L61Right.bytes, &L61Right_p3);
PERF_TIMER_STOP(VERIFY_line_61rl);
rct::key xsq;
sc_mul(xsq.bytes, x.bytes, x.bytes);
addKeys_acc_p3(&L61Right_p3, xsq, proof.T2);
ge_p3_tobytes(L61Right.bytes, &L61Right_p3);
PERF_TIMER_STOP(VERIFY_line_61rl_old);
}

if (!(L61Right == L61Left))
{
Expand Down Expand Up @@ -998,7 +1070,6 @@ bool bulletproof_VERIFY(const Bulletproof &proof)
PERF_TIMER_START_BP(VERIFY_line_24_25);
// Basically PAPER LINES 24-25
// Compute the curvepoints from G[i] and H[i]
ge_p3 inner_prod_p3 = ge_p3_identity;
rct::key yinvpow = rct::identity();
rct::key ypow = rct::identity();

Expand All @@ -1009,6 +1080,9 @@ bool bulletproof_VERIFY(const Bulletproof &proof)
winv[i] = invert(w[i]);
PERF_TIMER_STOP(VERIFY_line_24_25_invert);

std::vector<MultiexpData> multiexp_data;
multiexp_data.clear();
multiexp_data.reserve(MN*2);
for (size_t i = 0; i < MN; ++i)
{
// Convert the index to binary IN REVERSE and construct the scalar exponent
Expand Down Expand Up @@ -1040,46 +1114,75 @@ bool bulletproof_VERIFY(const Bulletproof &proof)
sc_muladd(tmp.bytes, z.bytes, ypow.bytes, tmp.bytes);
sc_mulsub(h_scalar.bytes, tmp.bytes, yinvpow.bytes, h_scalar.bytes);

// Now compute the basepoint's scalar multiplication
// Each of these could be written as a multiexp operation instead
addKeys3acc_p3(&inner_prod_p3, g_scalar, Gprecomp[i], h_scalar, Hprecomp[i]);
if (!(g_scalar == rct::zero()))
multiexp_data.push_back({g_scalar, Gi_p3[i]});
if (!(h_scalar == rct::zero()))
multiexp_data.push_back({h_scalar, Hi_p3[i]});

if (i != MN-1)
{
sc_mul(yinvpow.bytes, yinvpow.bytes, yinv.bytes);
sc_mul(ypow.bytes, ypow.bytes, y.bytes);
}
}
rct::key inner_prod;
ge_p3_tobytes(inner_prod.bytes, &inner_prod_p3);

rct::key inner_prod = bos_coster_heap_conv_robust(multiexp_data);
PERF_TIMER_STOP(VERIFY_line_24_25);

PERF_TIMER_START_BP(VERIFY_line_26);
// PAPER LINE 26
rct::key pprime;
sc_sub(tmp.bytes, rct::zero().bytes, proof.mu.bytes);
rct::addKeys(pprime, P, rct::scalarmultBase(tmp));
ge_p3 pprime_p3;
CHECK_AND_ASSERT_MES(ge_frombytes_vartime(&pprime_p3, pprime.bytes) == 0, false, "ge_frombytes_vartime failed");
// multiexp does not seem to give any speedup here
if(0)
{
PERF_TIMER_START_BP(VERIFY_line_26_new);
// PAPER LINE 26
std::vector<MultiexpData> multiexp_data;
multiexp_data.reserve(1+2*rounds);

sc_sub(tmp.bytes, rct::zero().bytes, proof.mu.bytes);
rct::addKeys(pprime, P, rct::scalarmultBase(tmp));
for (size_t i = 0; i < rounds; ++i)
{
sc_mul(tmp.bytes, w[i].bytes, w[i].bytes);
sc_mul(tmp2.bytes, winv[i].bytes, winv[i].bytes);
if (!(tmp == rct::zero()))
multiexp_data.push_back({tmp, proof.L[i]});
if (!(tmp2 == rct::zero()))
multiexp_data.push_back({tmp2, proof.R[i]});
}
sc_mul(tmp.bytes, proof.t.bytes, x_ip.bytes);
if (!(tmp == rct::zero()))
multiexp_data.push_back({tmp, rct::H});
addKeys(pprime, pprime, bos_coster_heap_conv_robust(multiexp_data));
PERF_TIMER_STOP(VERIFY_line_26_new);
}

for (size_t i = 0; i < rounds; ++i)
{
sc_mul(tmp.bytes, w[i].bytes, w[i].bytes);
sc_mul(tmp2.bytes, winv[i].bytes, winv[i].bytes);
PERF_TIMER_START_BP(VERIFY_line_26_old);
// PAPER LINE 26
sc_sub(tmp.bytes, rct::zero().bytes, proof.mu.bytes);
rct::addKeys(pprime, P, rct::scalarmultBase(tmp));
ge_p3 pprime_p3;
CHECK_AND_ASSERT_MES(ge_frombytes_vartime(&pprime_p3, pprime.bytes) == 0, false, "ge_frombytes_vartime failed");

for (size_t i = 0; i < rounds; ++i)
{
sc_mul(tmp.bytes, w[i].bytes, w[i].bytes);
sc_mul(tmp2.bytes, winv[i].bytes, winv[i].bytes);
#if 1
ge_dsmp cacheL, cacheR;
rct::precomp(cacheL, proof.L[i]);
rct::precomp(cacheR, proof.R[i]);
addKeys3acc_p3(&pprime_p3, tmp, cacheL, tmp2, cacheR);
ge_dsmp cacheL, cacheR;
rct::precomp(cacheL, proof.L[i]);
rct::precomp(cacheR, proof.R[i]);
addKeys3acc_p3(&pprime_p3, tmp, cacheL, tmp2, cacheR);
#else
rct::addKeys(pprime, pprime, rct::scalarmultKey(proof.L[i], tmp));
rct::addKeys(pprime, pprime, rct::scalarmultKey(proof.R[i], tmp2));
rct::addKeys(pprime, pprime, rct::scalarmultKey(proof.L[i], tmp));
rct::addKeys(pprime, pprime, rct::scalarmultKey(proof.R[i], tmp2));
#endif
}
sc_mul(tmp.bytes, proof.t.bytes, x_ip.bytes);
addKeys_acc_p3(&pprime_p3, tmp, rct::H);
ge_p3_tobytes(pprime.bytes, &pprime_p3);
PERF_TIMER_STOP(VERIFY_line_26_old);
}
sc_mul(tmp.bytes, proof.t.bytes, x_ip.bytes);
addKeys_acc_p3(&pprime_p3, tmp, rct::H);
ge_p3_tobytes(pprime.bytes, &pprime_p3);
PERF_TIMER_STOP(VERIFY_line_26);

PERF_TIMER_START_BP(VERIFY_step2_check);
sc_mul(tmp.bytes, proof.a.bytes, proof.b.bytes);
Expand Down
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