diff options
| -rw-r--r-- | src/ringct/bulletproofs.cc | 110 |
1 files changed, 87 insertions, 23 deletions
diff --git a/src/ringct/bulletproofs.cc b/src/ringct/bulletproofs.cc index 40d097f20..aa56b0589 100644 --- a/src/ringct/bulletproofs.cc +++ b/src/ringct/bulletproofs.cc @@ -65,6 +65,33 @@ static const rct::keyV twoN = vector_powers(TWO, maxN); static const rct::key ip12 = inner_product(oneN, twoN); static boost::mutex init_mutex; +//addKeys3acc_p3 +//aAbB += a*A + b*B where a, b are scalars, A, B are curve points +//A and B must be input after applying "precomp" +static void addKeys3acc_p3(ge_p3 *aAbB, const key &a, const ge_dsmp A, const key &b, const ge_dsmp B) +{ + ge_p3 rv; + ge_p1p1 p1; + ge_p2 p2; + ge_double_scalarmult_precomp_vartime2_p3(&rv, a.bytes, A, b.bytes, B); + ge_cached cached; + ge_p3_to_cached(&cached, aAbB); + ge_add(&p1, &rv, &cached); + ge_p1p1_to_p3(aAbB, &p1); +} + +static void addKeys_acc_p3(ge_p3 *acc_p3, const rct::key &a, const rct::key &point) +{ + ge_p3 p3; + CHECK_AND_ASSERT_THROW_MES(ge_frombytes_vartime(&p3, point.bytes) == 0, "ge_frombytes_vartime failed"); + ge_scalarmult_p3(&p3, a.bytes, &p3); + ge_cached cached; + ge_p3_to_cached(&cached, acc_p3); + ge_p1p1 p1; + ge_add(&p1, &p3, &cached); + ge_p1p1_to_p3(acc_p3, &p1); +} + static rct::key get_exponent(const rct::key &base, size_t idx) { static const std::string salt("bulletproof"); @@ -94,13 +121,13 @@ 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"); - rct::key res = rct::identity(); + ge_p3 res_p3 = ge_p3_identity; for (size_t i = 0; i < a.size(); ++i) { - rct::key term; - rct::addKeys3(term, a[i], Gprecomp[i], b[i], Hprecomp[i]); - rct::addKeys(res, res, term); + rct::addKeys3acc_p3(&res_p3, a[i], Gprecomp[i], b[i], Hprecomp[i]); } + rct::key res; + ge_p3_tobytes(res.bytes, &res_p3); return res; } @@ -111,11 +138,11 @@ 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"); - rct::key res = rct::identity(); + ge_p3 res_p3 = ge_p3_identity; for (size_t i = 0; i < a.size(); ++i) { - rct::key term; #if 0 + rct::key term; // we happen to know where A and B might fall, so don't bother checking the rest ge_dsmp *Acache = NULL, *Bcache = NULL; ge_dsmp Acache_custom[1], Bcache_custom[1]; @@ -136,13 +163,16 @@ static rct::key vector_exponent_custom(const rct::keyV &A, const rct::keyV &B, c Bcache = Bcache_custom; } rct::addKeys3(term, a[i], *Acache, b[i], *Bcache); + rct::addKeys(res, res, term); #else ge_dsmp Acache, Bcache; rct::precomp(Bcache, B[i]); - rct::addKeys3(term, a[i], A[i], b[i], Bcache); + rct::precomp(Acache, A[i]); + addKeys3acc_p3(&res_p3, a[i], Acache, b[i], Bcache); #endif - rct::addKeys(res, res, term); } + rct::key res; + ge_p3_tobytes(res.bytes, &res_p3); return res; } @@ -163,6 +193,24 @@ static rct::keyV vector_powers(const rct::key &x, size_t n) return res; } +/* Given a scalar, return the sum of its powers from 0 to n-1 */ +static rct::key vector_power_sum(const rct::key &x, size_t n) +{ + if (n == 0) + return rct::zero(); + rct::key res = rct::identity(); + if (n == 1) + return res; + rct::key prev = x; + for (size_t i = 1; i < n; ++i) + { + if (i > 1) + sc_mul(prev.bytes, prev.bytes, x.bytes); + sc_add(res.bytes, res.bytes, prev.bytes); + } + return res; +} + /* Given two scalar arrays, construct the inner product */ static rct::key inner_product(const rct::keyV &a, const rct::keyV &b) { @@ -876,12 +924,13 @@ bool bulletproof_VERIFY(const Bulletproof &proof) PERF_TIMER_START_BP(VERIFY_line_61); // PAPER LINE 61 - rct::key L61Left = rct::addKeys(rct::scalarmultBase(proof.taux), rct::scalarmultKey(rct::H, proof.t)); + rct::key L61Left; + rct::addKeys2(L61Left, proof.taux, proof.t, rct::H); const rct::keyV zpow = vector_powers(z, M+3); rct::key k; - const rct::key ip1y = vector_sum(vector_powers(y, MN)); + const rct::key ip1y = vector_power_sum(y, MN); sc_mulsub(k.bytes, zpow[2].bytes, ip1y.bytes, rct::zero().bytes); for (size_t j = 1; j <= M; ++j) { @@ -893,20 +942,32 @@ bool bulletproof_VERIFY(const Bulletproof &proof) 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); - for (size_t j = 0; j < M; ++j) + 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"); - tmp = rct::scalarmultKey(j < proof.V.size() ? proof.V[j] : rct::identity(), zpow[j+2]); - rct::addKeys(L61Right, L61Right, tmp); + // 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]); } - tmp = rct::scalarmultKey(proof.T1, x); - rct::addKeys(L61Right, L61Right, tmp); + addKeys_acc_p3(&L61Right_p3, x, proof.T1); rct::key xsq; sc_mul(xsq.bytes, x.bytes, x.bytes); - tmp = rct::scalarmultKey(proof.T2, xsq); - rct::addKeys(L61Right, L61Right, tmp); + addKeys_acc_p3(&L61Right_p3, xsq, proof.T2); + ge_p3_tobytes(L61Right.bytes, &L61Right_p3); PERF_TIMER_STOP(VERIFY_line_61rl); if (!(L61Right == L61Left)) @@ -937,7 +998,7 @@ 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] - rct::key inner_prod = rct::identity(); + ge_p3 inner_prod_p3 = ge_p3_identity; rct::key yinvpow = rct::identity(); rct::key ypow = rct::identity(); @@ -981,8 +1042,7 @@ bool bulletproof_VERIFY(const Bulletproof &proof) // Now compute the basepoint's scalar multiplication // Each of these could be written as a multiexp operation instead - rct::addKeys3(tmp, g_scalar, Gprecomp[i], h_scalar, Hprecomp[i]); - rct::addKeys(inner_prod, inner_prod, tmp); + addKeys3acc_p3(&inner_prod_p3, g_scalar, Gprecomp[i], h_scalar, Hprecomp[i]); if (i != MN-1) { @@ -990,6 +1050,8 @@ bool bulletproof_VERIFY(const Bulletproof &proof) sc_mul(ypow.bytes, ypow.bytes, y.bytes); } } + rct::key inner_prod; + ge_p3_tobytes(inner_prod.bytes, &inner_prod_p3); PERF_TIMER_STOP(VERIFY_line_24_25); PERF_TIMER_START_BP(VERIFY_line_26); @@ -997,6 +1059,8 @@ bool bulletproof_VERIFY(const Bulletproof &proof) 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"); for (size_t i = 0; i < rounds; ++i) { @@ -1006,15 +1070,15 @@ bool bulletproof_VERIFY(const Bulletproof &proof) ge_dsmp cacheL, cacheR; rct::precomp(cacheL, proof.L[i]); rct::precomp(cacheR, proof.R[i]); - rct::addKeys3(tmp, tmp, cacheL, tmp2, cacheR); - rct::addKeys(pprime, pprime, tmp); + 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)); #endif } sc_mul(tmp.bytes, proof.t.bytes, x_ip.bytes); - rct::addKeys(pprime, pprime, rct::scalarmultKey(rct::H, tmp)); + 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); |