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experimental crypto: L2S signature v2 (basic optimizations)

This commit is contained in:
sowle 2021-02-13 00:08:37 +03:00
parent b18be24334
commit 6cdb515fde
No known key found for this signature in database
GPG key ID: C07A24B2D89D49FC

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@ -1,6 +1,6 @@
// Copyright (c) 2020 Zano Project (https://zano.org/)
// Copyright (c) 2020 Locksmith (acmxddk@gmail.com)
// Copyright (c) 2020 sowle (crypto.sowle@gmail.com)
// Copyright (c) 2020-2021 Zano Project (https://zano.org/)
// Copyright (c) 2020-2021 Locksmith (acmxddk@gmail.com)
// Copyright (c) 2020-2021 sowle (val@zano.org, crypto.sowle@gmail.com)
// Distributed under the MIT/X11 software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#pragma once
@ -486,3 +486,420 @@ bool ml2s_lnk_sig_verif(const scalar_t& m, const std::vector<point_t>& B_array,
return true;
#undef CHECK_AND_FAIL_WITH_ERROR_IF_FALSE
}
////////////////////////////////////////////////////////////////////////////////////////////////////
// v 2
////////////////////////////////////////////////////////////////////////////////////////////////////
struct ml2s_signature_element_v2
{
point_t T0;
scalar_t t0;
point_t Z;
std::vector<scalar_t> r_array; // size = n
std::vector<point_t> H_array; // size = n
point_t T;
scalar_t t;
};
struct ml2s_signature_v2
{
std::vector<ml2s_signature_element_v2> elements; // size = L
};
bool ml2s_lnk_sig_gen_v2(const scalar_t& m, const std::vector<point_t>& B_array, const std::vector<scalar_t>& b_array,
const std::vector<size_t>& s_array, const std::vector<point_t>& I_array, ml2s_signature_v2& signature, uint8_t* p_err = nullptr)
{
#define CHECK_AND_FAIL_WITH_ERROR_IF_FALSE(cond, err_code) \
if (!(cond)) { LOG_PRINT_RED("ml2s_lnk_sig_gen: \"" << #cond << "\" is false at " << LOCATION_SS << ENDL << "error code = " << err_code, LOG_LEVEL_3); \
if (p_err) *p_err = err_code; return false; }
#ifndef NDEBUG
# define DBG_CHECK_AND_FAIL_WITH_ERROR_IF_FALSE(cond, err_code) CHECK_AND_ASSERT_MES_CUSTOM(cond, false, if (p_err) *p_err = err_code, "ml2s_lnk_sig_gen check failed: " << #cond)
#else
# define DBG_CHECK_AND_FAIL_WITH_ERROR_IF_FALSE(cond, err_code)
#endif
// check boundaries
size_t L = b_array.size();
size_t N = 2 * B_array.size();
size_t n = log2sz(N);
CHECK_AND_FAIL_WITH_ERROR_IF_FALSE(s_array.size() == L, 0);
CHECK_AND_FAIL_WITH_ERROR_IF_FALSE(1ull << n == N, 1);
CHECK_AND_FAIL_WITH_ERROR_IF_FALSE(L > 0, 2);
CHECK_AND_FAIL_WITH_ERROR_IF_FALSE(L <= N / 2, 3);
// initialize signature
signature.elements.resize(L);
for (size_t i = 0; i < L; ++i)
{
signature.elements[i].H_array.resize(n);
signature.elements[i].r_array.resize(n);
}
std::vector<scalar_t> b_inv_array;
b_inv_array.reserve(L);
for (size_t i = 0; i < L; ++i)
b_inv_array.emplace_back(b_array[i].reciprocal());
const scalar_t z = hash_helper_t::hs(m, B_array, I_array);
auto hash_point_lambda = [&z](const point_t& point) { return point + z * hash_helper_t::hp(point); };
std::vector<point_t> A_array; // size == L
A_array.reserve(L);
for (size_t i = 0; i < L; ++i)
A_array.emplace_back(c_point_G + z * I_array[i]);
std::vector<point_t> P_array; // size == N // 2
P_array.reserve(B_array.size());
for (size_t i = 0; i < B_array.size(); ++i)
P_array.emplace_back(hash_point_lambda(B_array[i]));
point_t I_sum;
I_sum.zero();
for (size_t i = 0; i < L; ++i)
I_sum = I_sum + I_array[i];
point_t Q_shift = hash_helper_t::hp(I_sum);
CHECK_AND_FAIL_WITH_ERROR_IF_FALSE(P_array.size() * 2 == N, 4);
std::vector<point_t> X_array(N);
// X_array = { P_array[0], Q_array[0], P_array[1], Q_array[1], etc. }
for (size_t i = 0; i < N; ++i)
{
if (i % 2 == 0)
X_array[i] = P_array[i / 2];
else
X_array[i] = hash_point_lambda(Q_shift + B_array[i / 2]);
}
for (size_t i = 0; i < L; ++i)
{
size_t s_idx = s_array[i];
CHECK_AND_FAIL_WITH_ERROR_IF_FALSE(s_idx < B_array.size() && 2 * s_idx + 1 < X_array.size(), 5);
point_t Ap = b_inv_array[i] * X_array[2 * s_idx];
CHECK_AND_FAIL_WITH_ERROR_IF_FALSE(Ap == A_array[i], 6);
}
///
struct intermediate_element_t
{
scalar_t f;
scalar_t k0;
scalar_t q;
size_t M_cnt;
size_t z;
size_t h;
scalar_t a;
scalar_t x;
std::vector<point_t> Y_array;
};
std::vector<intermediate_element_t> interms(L);
// challenge c0
scalar_t e = hash_helper_t::hs(z);
hash_helper_t::hs_t hsc;
hsc.add_scalar(e);
hsc.add_points_array(X_array);
for (size_t i = 0; i < L; ++i)
{
auto& interm = interms[i];
auto& sel = signature.elements[i];
const point_t& Z0 = A_array[i]; // b_inv_array[i] * X_array[2 * s_array[i]] + 0 * X_array[2 * s + 1], as k1 == 0 always
interm.f.make_random();
sel.Z = interm.f * Z0;
interm.k0 = interm.f * b_inv_array[i];
interm.q.make_random();
sel.T0 = interm.q * Z0;
hsc.add_point(sel.T0);
hsc.add_point(sel.Z);
}
scalar_t c0 = hsc.calc_hash();
// challenges c11, c13
hsc.add_scalar(c0);
for (size_t i = 0; i < L; ++i)
{
auto& interm = interms[i];
auto& sel = signature.elements[i];
sel.t0 = interm.q - interm.f * c0;
interm.M_cnt = N;
interm.z = 2 * s_array[i];
interm.h = 2 * s_array[i] + 1; // we already checked s_array elements against X_array.size() above
interm.a = 1;
interm.q.make_random(); // new q
interm.Y_array = X_array;
sel.H_array[0] = interm.k0 / interm.q * X_array[interm.h]; // H1
hsc.add_scalar(sel.t0);
hsc.add_point(sel.H_array[0]);
}
// challenges c11, c13
#ifndef NDEBUG
// these vectors are only needed for self-check in the end
std::vector<scalar_t> c1_array(n); // counting from 0, so c11 is c1_array[0], will have n elements
std::vector<scalar_t> c3_array(n - 1); // the same, will have n - 1 elements
#endif
scalar_t ci1 = hsc.calc_hash();
scalar_t ci3 = hash_helper_t::hs(ci1);
// ci1, ci3 for i in [2; n] -- corresponds c1_array for i in [1; n - 1], c3_array for i in [1; n - 2]
for (size_t idx_n = 0; idx_n < n - 1; ++idx_n)
{
#ifndef NDEBUG
c1_array[idx_n] = ci1;
c3_array[idx_n] = ci3;
#endif
std::vector<const scalar_t*> c_array = { &c_scalar_1, &ci1, &c_scalar_1, &ci3 };
hsc.add_scalar(ci1);
for (size_t idx_L = 0; idx_L < L; ++idx_L)
{
auto& interm = interms[idx_L];
auto& sel = signature.elements[idx_L];
const scalar_t& e_local = *c_array[interm.z % 4];
const scalar_t& g_local = *c_array[interm.h % 4];
sel.r_array[idx_n] = interm.q * g_local / e_local; // r_i
interm.a *= e_local;
DBG_CHECK_AND_FAIL_WITH_ERROR_IF_FALSE(is_power_of_2(interm.M_cnt), 200);
interm.M_cnt = interm.M_cnt / 2;
// TODO: check M_scalar is power of 2
for (size_t j = 0; j < interm.M_cnt; ++j)
interm.Y_array[j] = (interm.Y_array[2 * j] + *c_array[(2 * j + 1) % 4] * interm.Y_array[2 * j + 1]) / e_local;
interm.z /= 2;
interm.h = invert_last_bit(interm.z);
interm.q.make_random();
sel.H_array[idx_n + 1] = interm.k0 / interm.q * interm.Y_array[interm.h]; // H_{i+1}
hsc.add_scalar(sel.r_array[idx_n]);
hsc.add_point(sel.H_array[idx_n + 1]);
}
ci1 = hsc.calc_hash();
ci3 = hash_helper_t::hs(ci1);
}
// challenge cn
#ifndef NDEBUG
c1_array[n - 1] = ci1;
#endif
// challenge c
hsc.add_scalar(ci1);
for (size_t i = 0; i < L; ++i)
{
auto& interm = interms[i];
auto& sel = signature.elements[i];
CHECK_AND_FAIL_WITH_ERROR_IF_FALSE((interm.z == 0 && interm.h == 1) || (interm.z == 1 && interm.h == 0), 7);
const scalar_t& e_local = interm.z == 0 ? c_scalar_1 : ci1;
const scalar_t& g_local = interm.z == 0 ? ci1 : c_scalar_1;
sel.r_array[n - 1] = interm.q * g_local / e_local; // r_n
interm.a *= e_local;
interm.x = interm.a / interm.k0;
interm.q.make_random(); // qn
DBG_CHECK_AND_FAIL_WITH_ERROR_IF_FALSE(interm.k0 * X_array[2 * s_array[i]] == sel.Z, 201);
point_t W = sel.Z;
for (size_t j = 0; j < n; ++j)
W = W + sel.r_array[j] * sel.H_array[j];
sel.T = interm.q * W;
hsc.add_scalar(sel.r_array[n - 1]);
hsc.add_point(sel.T);
}
scalar_t c = hsc.calc_hash();
for (size_t i = 0; i < L; ++i)
{
auto& interm = interms[i];
auto& sel = signature.elements[i];
sel.t = interm.q - interm.x * c;
}
// L2S signature is complete
#ifndef NDEBUG
// self-check
for (size_t i = 0; i < L; ++i)
{
auto& interm = interms[i];
auto& sel = signature.elements[i];
point_t W = sel.Z;
for (size_t j = 0; j < n; ++j)
W = W + sel.r_array[j] * sel.H_array[j];
DBG_CHECK_AND_FAIL_WITH_ERROR_IF_FALSE(sel.T == interm.q * W, 230);
point_t R;
R.zero();
bool r = ml2s_rsum(n, X_array, c1_array, c3_array, R);
DBG_CHECK_AND_FAIL_WITH_ERROR_IF_FALSE(r, 231);
DBG_CHECK_AND_FAIL_WITH_ERROR_IF_FALSE(R == interm.x * W, 232);
DBG_CHECK_AND_FAIL_WITH_ERROR_IF_FALSE(sel.t == interm.q - interm.x * c, 233);
DBG_CHECK_AND_FAIL_WITH_ERROR_IF_FALSE(sel.t * W + c * R == sel.T, 234);
}
#endif // #ifndef NDEBUG
return true;
#undef DBG_CHECK_AND_FAIL_WITH_ERROR_IF_FALSE
#undef CHECK_AND_FAIL_WITH_ERROR_IF_FALSE
} // ml2s_lnk_sig_gen
bool ml2s_lnk_sig_verif_v2(const scalar_t& m, const std::vector<point_t>& B_array, std::vector<point_t>& I_array,
const ml2s_signature_v2& signature, uint8_t* p_err = nullptr)
{
#define CHECK_AND_FAIL_WITH_ERROR_IF_FALSE(cond, err_code) \
if (!(cond)) { LOG_PRINT_RED("ml2s_lnk_sig_verif: \"" << #cond << "\" is false at " << LOCATION_SS << ENDL << "error code = " << err_code, LOG_LEVEL_3); \
if (p_err) *p_err = err_code; return false; }
size_t L = signature.elements.size();
CHECK_AND_FAIL_WITH_ERROR_IF_FALSE(L > 0, 0);
size_t n = signature.elements[0].r_array.size();
CHECK_AND_FAIL_WITH_ERROR_IF_FALSE(n < 32, 4);
size_t N = (size_t)1 << n;
CHECK_AND_FAIL_WITH_ERROR_IF_FALSE(B_array.size() == N / 2, 5);
const scalar_t z = hash_helper_t::hs(m, B_array, I_array);
auto hash_point_lambda = [&z](const point_t& point) { return point + z * hash_helper_t::hp(point); };
std::vector<point_t> A_array;
A_array.resize(L);
for (size_t i = 0; i < L; ++i)
{
A_array[i] = I_array[i].mul_plus_G(z); // = c_point_G + z * I_array[i];
CHECK_AND_FAIL_WITH_ERROR_IF_FALSE(signature.elements[i].r_array.size() == n, 1);
CHECK_AND_FAIL_WITH_ERROR_IF_FALSE(signature.elements[i].H_array.size() == n, 2);
}
scalar_t e = hash_helper_t::hs(z);
point_t I_sum;
I_sum.zero();
for (size_t i = 0; i < L; ++i)
I_sum = I_sum + I_array[i];
point_t Q_shift = hash_helper_t::hp(I_sum);
std::vector<point_t> X_array(N);
for (size_t i = 0; i < N; i += 2)
X_array[i] = B_array[i / 2] + z * hash_helper_t::hp(B_array[i / 2]);
for (size_t i = 1; i < N; i += 2)
X_array[i] = hash_point_lambda(Q_shift + B_array[i / 2]);
// challenge c0
hash_helper_t::hs_t hsc;
hsc.reserve(1 + N + 3 * L);
hsc.add_scalar(e);
hsc.add_points_array(X_array);
for (size_t i = 0; i < L; ++i)
{
auto& sel = signature.elements[i];
hsc.add_point(sel.T0);
hsc.add_point(sel.Z);
}
e = hsc.calc_hash();
scalar_t c0 = e;
// check t0 * Z0 + c0 * Z == T0
for (size_t i = 0; i < L; ++i)
{
auto& sel = signature.elements[i];
CHECK_AND_FAIL_WITH_ERROR_IF_FALSE(sel.t0 * A_array[i] + c0 * sel.Z == sel.T0, 7);
}
// challenges c11, c13
std::vector<scalar_t> c1_array; // counting from 0, so c11 is c1_array[0], will have n elements
std::vector<scalar_t> c3_array; // the same, will have n - 1 elements
hsc.add_scalar(e);
for (size_t i = 0; i < L; ++i)
{
auto& sel = signature.elements[i];
hsc.add_scalar(sel.t0);
hsc.add_point(sel.H_array[0]);
}
e = hsc.calc_hash();
c1_array.emplace_back(e);
c3_array.emplace_back(hash_helper_t::hs(e));
// ci1, ci3 for i in [2; n] -- corresponds c1_array for i in [1; n - 1], c3_array for i in [1; n - 2]
for (size_t i = 1; i < n; ++i)
{
hsc.add_scalar(e);
for (size_t j = 0; j < L; ++j)
{
auto& sel = signature.elements[j];
hsc.add_scalar(sel.r_array[i - 1]);
hsc.add_point(sel.H_array[i]);
}
e = hsc.calc_hash();
c1_array.emplace_back(e);
if (i != n - 1)
c3_array.emplace_back(hash_helper_t::hs(e));
}
// challenge c
hsc.add_scalar(e);
for (size_t i = 0; i < L; ++i)
{
auto& sel = signature.elements[i];
hsc.add_scalar(sel.r_array[n - 1]);
hsc.add_point(sel.T);
}
scalar_t c = hsc.calc_hash();
// Rsum
point_t R = c_point_G;
CHECK_AND_FAIL_WITH_ERROR_IF_FALSE(ml2s_rsum(n, X_array, c1_array, c3_array, R), 8);
point_t cR = c * R;
// final checks
for (size_t i = 0; i < L; ++i)
{
auto& sel = signature.elements[i];
point_t S = sel.Z;
for (size_t j = 0; j < n; ++j)
{
S = S + sel.r_array[j] * sel.H_array[j];
CHECK_AND_FAIL_WITH_ERROR_IF_FALSE(!S.is_zero(), 9);
CHECK_AND_FAIL_WITH_ERROR_IF_FALSE(sel.r_array[j] != 0, 10);
CHECK_AND_FAIL_WITH_ERROR_IF_FALSE(!sel.H_array[j].is_zero(), 11);
}
CHECK_AND_FAIL_WITH_ERROR_IF_FALSE(sel.t * S + cR == sel.T, 12);
}
return true;
#undef CHECK_AND_FAIL_WITH_ERROR_IF_FALSE
}