static int compute_min_prec(double &rho, int d, double delta, double eta, double epsilon,
MinPrecAlgo algo)
{
int old_prec = Float::set_prec(53);
Float f_minprec, f_rho, f_d, f_eta, f_delta, f_epsilon, tmp1, tmp2;
// These four conversions are exact
f_d = static_cast<double>(d);
f_eta = eta;
f_delta = delta;
f_epsilon = epsilon;
if (algo == MINPREC_L2)
{
// eta - 0.5 is an exact fp operation
if (f_epsilon > eta - 0.5)
f_epsilon = eta - 0.5;
tmp1 = 1.0;
tmp1.sub(tmp1, f_delta, GMP_RNDD);
if (f_epsilon > tmp1)
f_epsilon = tmp1;
// now fEpsilon <= min(epsilon, eta - 0.5, 1 - delta);
}
// Computes tmp1 >= (1 + eta) ^ 2 + epsilon
tmp1 = 1.0; // exact
tmp1.add(f_eta, tmp1, GMP_RNDU); // >= 1 + eta
tmp1.mul(tmp1, tmp1, GMP_RNDU); // >= (1 + eta) ^ 2
tmp1.add(tmp1, f_epsilon, GMP_RNDU);
// Computes tmp2 <= delta - eta ^ 2
tmp2.mul(f_eta, f_eta, GMP_RNDU);
tmp2.sub(f_delta, tmp2, GMP_RNDD);
FPLLL_CHECK(tmp2 > 0, "invalid LLL parameters, eta must be < sqrt(delta)");
// Computes rho >= ((1 + eta) ^ 2 + epsilon) / (delta - eta ^ 2)
f_rho.div(tmp1, tmp2, GMP_RNDU);
rho = f_rho.get_d(GMP_RNDU);
/* Computes minprec >= constant + 2 * log2(d) - log2(epsilon) + d * log2(rho)
(constant = 5 for GSO, 10 for LLL) */
tmp1.log(f_d, GMP_RNDU); // >= log(d)
tmp1.mul_2si(tmp1, 1); // >= 2 * log(d)
tmp2.log(f_epsilon, GMP_RNDD); // <= log(epsilon) (<= 0)
tmp1.sub(tmp1, tmp2, GMP_RNDU); // >= 2 * log(d) - log(epsilon)
tmp2.log(f_rho, GMP_RNDU); // >= log(rho)
tmp2.mul(f_d, tmp2, GMP_RNDU); // >= d * log(rho)
tmp1.add(tmp1, tmp2, GMP_RNDU); // >= 2*log(d)-log(epsilon)+d*log(rho)
tmp2 = 2.0; // exact
tmp2.log(tmp2, GMP_RNDD); // <= log(2)
tmp1.div(tmp1, tmp2, GMP_RNDU); // >= 2*log2(d)-log2(epsilon)+d*log2(rho)
tmp2 = (algo == MINPREC_L2) ? 10.0 : 5.0;
f_minprec.add(tmp1, tmp2, GMP_RNDU);
int minprec = static_cast<int>(ceil(f_minprec.get_d(GMP_RNDU)));
mpfr_free_cache();
Float::set_prec(old_prec);
return minprec;
}
void EnumerationDyn<FT>::enumerate(int first, int last, FT &fmaxdist, long fmaxdistexpo,
const vector<FT> &target_coord, const vector<enumxt> &subtree,
const vector<enumf> &pruning, bool _dual, bool subtree_reset)
{
bool solvingsvp = target_coord.empty();
dual = _dual;
pruning_bounds = pruning;
target = target_coord;
if (last == -1)
last = _gso.d;
d = last - first;
fx.resize(d);
FPLLL_CHECK(d < maxdim, "enumerate: dimension is too high");
FPLLL_CHECK((solvingsvp || !dual), "CVP for dual not implemented! What does that even mean? ");
FPLLL_CHECK((subtree.empty() || !dual), "Subtree enumeration for dual not implemented!");
resetflag = !_max_indices.empty();
if (resetflag)
reset_depth = _max_indices[last - subtree.size() - 1];
if (solvingsvp)
{
for (int i = 0; i < d; ++i)
center_partsum[i] = 0.0;
}
else
{
for (int i = 0; i < d; ++i)
center_partsum[i] = target_coord[i + first].get_d();
}
FT fr, fmu, fmaxdistnorm;
long rexpo, normexp = -1;
for (int i = 0; i < d; ++i)
{
fr = _gso.get_r_exp(i + first, i + first, rexpo);
normexp = max(normexp, rexpo + fr.exponent());
}
fmaxdistnorm.mul_2si(fmaxdist, dual ? normexp - fmaxdistexpo : fmaxdistexpo - normexp);
maxdist = fmaxdistnorm.get_d(GMP_RNDU);
_evaluator.set_normexp(normexp);
if (dual)
{
for (int i = 0; i < d; ++i)
{
fr = _gso.get_r_exp(i + first, i + first, rexpo);
fr.mul_2si(fr, rexpo - normexp);
rdiag[d - i - 1] = enumf(1.0) / fr.get_d();
}
for (int i = 0; i < d; ++i)
{
for (int j = i + 1; j < d; ++j)
{
_gso.get_mu(fmu, j + first, i + first);
mut[d - j - 1][d - i - 1] = -fmu.get_d();
}
}
}
else
{
for (int i = 0; i < d; ++i)
{
fr = _gso.get_r_exp(i + first, i + first, rexpo);
fr.mul_2si(fr, rexpo - normexp);
rdiag[i] = fr.get_d();
}
for (int i = 0; i < d; ++i)
{
for (int j = i + 1; j < d; ++j)
{
_gso.get_mu(fmu, j + first, i + first);
mut[i][j] = fmu.get_d();
}
}
}
subsoldists = rdiag;
save_rounding();
prepare_enumeration(subtree, solvingsvp, subtree_reset);
do_enumerate();
restore_rounding();
fmaxdistnorm = maxdist; // Exact
fmaxdist.mul_2si(fmaxdistnorm, dual ? fmaxdistexpo - normexp : normexp - fmaxdistexpo);
if (dual && !_evaluator.empty())
{
for (auto it = _evaluator.begin(), itend = _evaluator.end(); it != itend; ++it)
reverse_by_swap(it->second, 0, d - 1);
}
}
static int shortest_vector_ex(IntMatrix &b, IntVect &sol_coord, SVPMethod method,
const vector<double> &pruning, int flags, EvaluatorMode eval_mode,
long long &sol_count, vector<IntVect> *subsol_coord = nullptr,
vector<enumf> *subsol_dist = nullptr)
{
bool findsubsols = (subsol_coord != nullptr) && (subsol_dist != nullptr);
// d = lattice dimension (note that it might decrease during preprocessing)
int d = b.get_rows();
// n = dimension of the space
int n = b.get_cols();
FPLLL_CHECK(d > 0 && n > 0, "shortestVector: empty matrix");
FPLLL_CHECK(d <= n, "shortestVector: number of vectors > size of the vectors");
// Sets the floating-point precision
// Error bounds on GSO are valid if prec >= minprec
double rho;
int min_prec = gso_min_prec(rho, d, LLL_DEF_DELTA, LLL_DEF_ETA);
int prec = max(53, min_prec + 10);
int old_prec = Float::set_prec(prec);
// Allocates space for vectors and matrices in constructors
IntMatrix empty_mat;
MatGSO<Integer, Float> gso(b, empty_mat, empty_mat, GSO_INT_GRAM);
Float max_dist;
Integer int_max_dist;
Integer itmp1;
// Computes the Gram-Schmidt orthogonalization in floating-point
gso.update_gso();
gen_zero_vect(sol_coord, d);
// If the last b_i* are too large, removes them to avoid an underflow
int new_d = last_useful_index(gso.get_r_matrix());
if (new_d < d)
{
// FPLLL_TRACE("Ignoring the last " << d - new_d << " vector(s)");
d = new_d;
}
if (flags & SVP_DUAL)
{
max_dist = 1.0 / gso.get_r_exp(d - 1, d - 1);
if (flags & SVP_VERBOSE)
{
cout << "max_dist = " << max_dist << endl;
}
}
else
{
/* Computes a bound for the enumeration. This bound would work for an
exact algorithm, but we will increase it later to ensure that the fp
algorithm finds a solution */
get_basis_min(int_max_dist, b, 0, d);
max_dist.set_z(int_max_dist, GMP_RNDU);
}
// Initializes the evaluator of solutions
Evaluator<Float> *evaluator;
if (method == SVPM_FAST)
{
evaluator = new FastEvaluator<Float>(d, gso.get_mu_matrix(), gso.get_r_matrix(), eval_mode, 0,
findsubsols);
}
else if (method == SVPM_PROVED)
{
ExactEvaluator *p = new ExactEvaluator(d, b, gso.get_mu_matrix(), gso.get_r_matrix(), eval_mode,
0, findsubsols);
p->int_max_dist = int_max_dist;
evaluator = p;
}
else
{
FPLLL_ABORT("shortestVector: invalid evaluator type");
}
evaluator->init_delta_def(prec, rho, true);
if (!(flags & SVP_OVERRIDE_BND) && (eval_mode == EVALMODE_SV || method == SVPM_PROVED))
{
Float ftmp1;
bool result = evaluator->get_max_error_aux(max_dist, true, ftmp1);
FPLLL_CHECK(result, "shortestVector: cannot compute an initial bound");
max_dist.add(max_dist, ftmp1, GMP_RNDU);
}
// Main loop of the enumeration
enumerate_svp(d, gso, max_dist, *evaluator, pruning, flags);
int result = RED_ENUM_FAILURE;
if (eval_mode != EVALMODE_SV)
{
result = RED_SUCCESS;
sol_count = evaluator->sol_count * 2;
}
else if (!evaluator->sol_coord.empty())
{
/*Float fMaxError;
validMaxError = evaluator->get_max_error(fMaxError);
max_error = fMaxError.get_d(GMP_RNDU);*/
for (int i = 0; i < d; i++)
{
itmp1.set_f(evaluator->sol_coord[i]);
sol_coord[i].add(sol_coord[i], itmp1);
}
result = RED_SUCCESS;
}
if (findsubsols)
{
subsol_coord->clear();
subsol_dist->clear();
subsol_dist->resize(evaluator->sub_sol_coord.size());
for (size_t i = 0; i < evaluator->sub_sol_coord.size(); ++i)
{
(*subsol_dist)[i] = evaluator->sub_sol_dist[i];
IntVect ss_c;
for (size_t j = 0; j < evaluator->sub_sol_coord[i].size(); ++j)
{
itmp1.set_f(evaluator->sub_sol_coord[i][j]);
ss_c.emplace_back(itmp1);
}
subsol_coord->emplace_back(std::move(ss_c));
}
}
delete evaluator;
Float::set_prec(old_prec);
return result;
}
/**
* interface called from call_bkz() from main.cpp.
*/
int bkz_reduction(IntMatrix *B, IntMatrix *U, const BKZParam ¶m, FloatType float_type,
int precision)
{
IntMatrix empty_mat;
IntMatrix &u = U ? *U : empty_mat;
IntMatrix &u_inv = empty_mat;
FPLLL_CHECK(B, "B == NULL in bkzReduction");
if (U && (!u.empty()))
{
u.gen_identity(B->get_rows());
}
double lll_delta = param.delta < 1 ? param.delta : LLL_DEF_DELTA;
FloatType sel_ft = (float_type != FT_DEFAULT) ? float_type : FT_DOUBLE;
FPLLL_CHECK(!(sel_ft == FT_MPFR && precision == 0),
"Missing precision for BKZ with floating point type mpfr");
/* lllwrapper (no FloatType needed, -m ignored) */
if (param.flags & BKZ_NO_LLL)
zeros_last(*B, u, u_inv);
else
{
Wrapper wrapper(*B, u, u_inv, lll_delta, LLL_DEF_ETA, LLL_DEFAULT);
if (!wrapper.lll())
return wrapper.status;
}
/* bkz (with float_type) */
int status;
if (sel_ft == FT_DOUBLE)
{
status = bkz_reduction_f<FP_NR<double>>(*B, param, sel_ft, lll_delta, u, u_inv);
}
#ifdef FPLLL_WITH_LONG_DOUBLE
else if (sel_ft == FT_LONG_DOUBLE)
{
status = bkz_reduction_f<FP_NR<long double>>(*B, param, sel_ft, lll_delta, u, u_inv);
}
#endif
#ifdef FPLLL_WITH_DPE
else if (sel_ft == FT_DPE)
{
status = bkz_reduction_f<FP_NR<dpe_t>>(*B, param, sel_ft, lll_delta, u, u_inv);
}
#endif
#ifdef FPLLL_WITH_QD
else if (sel_ft == FT_DD)
{
status = bkz_reduction_f<FP_NR<dd_real>>(*B, param, sel_ft, lll_delta, u, u_inv);
}
else if (sel_ft == FT_QD)
{
status = bkz_reduction_f<FP_NR<qd_real>>(*B, param, sel_ft, lll_delta, u, u_inv);
}
#endif
else if (sel_ft == FT_MPFR)
{
int old_prec = FP_NR<mpfr_t>::set_prec(precision);
status = bkz_reduction_f<FP_NR<mpfr_t>>(*B, param, sel_ft, lll_delta, u, u_inv);
FP_NR<mpfr_t>::set_prec(old_prec);
}
else
{
FPLLL_ABORT("Compiled without support for BKZ reduction with " << FLOAT_TYPE_STR[sel_ft]);
}
zeros_first(*B, u, u_inv);
return status;
}
int closest_vector(IntMatrix &b, const IntVect &int_target, IntVect &sol_coord, int method, int flags)
{
// d = lattice dimension (note that it might decrease during preprocessing)
int d = b.get_rows();
// n = dimension of the space
int n = b.get_cols();
FPLLL_CHECK(d > 0 && n > 0, "closestVector: empty matrix");
FPLLL_CHECK(d <= n, "closestVector: number of vectors > size of the vectors");
// Sets the floating-point precision
// Error bounds on GSO are valid if prec >= minprec
double rho;
int min_prec = gso_min_prec(rho, d, LLL_DEF_DELTA, LLL_DEF_ETA);
int prec = max(53, min_prec + 10);
int old_prec = Float::set_prec(prec);
// Allocates space for vectors and matrices in constructors
IntMatrix empty_mat;
MatGSO<Integer, Float> gso(b, empty_mat, empty_mat, GSO_INT_GRAM);
FloatVect target_coord;
Float max_dist;
Integer itmp1;
// Computes the Gram-Schmidt orthogonalization in floating-point
gso.update_gso();
gen_zero_vect(sol_coord, d);
/* Applies Babai's algorithm. Because we use fp, it might be necessary to
do it several times (if ||target|| >> ||b_i||) */
FloatMatrix float_matrix(d, n);
FloatVect target(n), babai_sol;
IntVect int_new_target = int_target;
for (int i = 0; i < d; i++)
for (int j = 0; j < n; j++)
float_matrix(i, j).set_z(b(i, j));
for (int loop_idx = 0;; loop_idx++)
{
if (loop_idx >= 0x100 && ((loop_idx & (loop_idx - 1)) == 0))
FPLLL_INFO("warning: possible infinite loop in Babai's algorithm");
for (int i = 0; i < n; i++)
{
target[i].set_z(int_new_target[i]);
}
babai(float_matrix, gso.get_mu_matrix(), gso.get_r_matrix(), target, babai_sol);
int idx;
for (idx = 0; idx < d && babai_sol[idx] >= -1 && babai_sol[idx] <= 1; idx++)
{
}
if (idx == d)
break;
for (int i = 0; i < d; i++)
{
itmp1.set_f(babai_sol[i]);
sol_coord[i].add(sol_coord[i], itmp1);
for (int j = 0; j < n; j++)
int_new_target[j].submul(itmp1, b(i, j));
}
}
// FPLLL_TRACE("BabaiSol=" << sol_coord);
get_gscoords(float_matrix, gso.get_mu_matrix(), gso.get_r_matrix(), target, target_coord);
/* Computes a very large bound to make the algorithm work
until the first solution is found */
max_dist = 0.0;
for (int i = 1; i < d; i++)
{
// get_r_exp(i, i) = r(i, i) because gso is initialized without GSO_ROW_EXPO
max_dist.add(max_dist, gso.get_r_exp(i, i));
}
vector<int> max_indices;
if (method & CVPM_PROVED)
{
// For Exact CVP, we need to reset enum below depth with maximal r_i
max_indices = vector<int>(d);
int cur, max_index, previous_max_index;
previous_max_index = max_index = d-1;
Float max_val;
while (max_index > 0)
{
max_val = gso.get_r_exp(max_index, max_index);
for (cur = previous_max_index - 1 ; cur >= 0 ; --cur)
{
if (max_val <= gso.get_r_exp(cur, cur))
{
max_val = gso.get_r_exp(cur, cur);
max_index = cur;
}
}
for (cur = max_index ; cur < previous_max_index ; ++cur)
max_indices[cur] = max_index;
max_indices[previous_max_index] = previous_max_index;
previous_max_index = max_index;
--max_index;
}
}
FPLLL_TRACE("max_indices " << max_indices);
FastEvaluator<Float> evaluator(n, gso.get_mu_matrix(), gso.get_r_matrix(), EVALMODE_CV);
// Main loop of the enumeration
Enumeration<Float> enumobj(gso, evaluator, max_indices);
enumobj.enumerate(0, d, max_dist, 0, target_coord);
int result = RED_ENUM_FAILURE;
if (!evaluator.sol_coord.empty())
{
FPLLL_TRACE("evaluator.sol_coord=" << evaluator.sol_coord);
if (flags & CVP_VERBOSE)
FPLLL_INFO("max_dist=" << max_dist);
for (int i = 0; i < d; i++)
{
itmp1.set_f(evaluator.sol_coord[i]);
sol_coord[i].add(sol_coord[i], itmp1);
}
result = RED_SUCCESS;
}
Float::set_prec(old_prec);
return result;
}
