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mce_qd complete

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(doesn't work though)
This commit is contained in:
Mirek Kratochvil 2012-10-27 11:49:24 +02:00
parent aa5b1ac2cc
commit cd1a321041
2 changed files with 77 additions and 16 deletions
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7
include/codecrypt.h
View file

@ -392,9 +392,10 @@ public:
std::vector<uint> support; //computed goppa support
polynomial g; //computed goppa polynomial
std::vector<polynomial> sqInv;
std::vector<bvector> Hc; //signature lines of pre-permuted check matrix
std::vector<uint> support_pos; //pre-permuted positions of support rows
//blocks of signature lines of pre-permuted check matrix
std::vector<std::vector<bvector> > Hc;
//pre-permuted positions of support rows
std::vector<uint> support_pos;
int decrypt (const bvector&, bvector&);
int prepare();

86
lib/mce_qd.cpp
View file

@ -333,16 +333,17 @@ int mce_qd::generate (pubkey&pub, privkey&priv, prng&rng,
int privkey::prepare()
{
uint s, i, j;
std::cout << "prepare" << std::endl;
//compute H signature from essence
Hsig.resize (fld.n / 2);
Hsig[0] = fld.inv (essence[fld.m - 1]);
for (uint s = 0; s < fld.m - 1; ++s) {
uint i = 1 << s; //i = 2^s
for (s = 0; s < fld.m - 1; ++s) {
i = 1 << s; //i = 2^s
Hsig[i] = fld.inv (fld.add (essence[s], essence[fld.m - 1]) );
for (uint j = 1; j < i; ++j)
for (j = 1; j < i; ++j)
Hsig[i + j] = fld.inv
(fld.add
(fld.inv (Hsig[i]),
@ -354,17 +355,76 @@ int privkey::prepare()
//compute the support
support.resize (fld.n / 2);
for (uint i = 0; i < fld.n / 2; ++i) {
std::set<uint> used_support;
for (i = 0; i < fld.n / 2; ++i) {
support[i] = fld.add
(fld.inv (Hsig[i]),
essence[fld.m - 1]);
//support consistency check
if (used_support.count (support[i]) )
return 1;
used_support.insert (support[i]);
}
//TODO prepare permuted Hsig (that can be applied to the ciphertext)
//prepare permuted Hsig (so that it can be applied directly)
//and prepare reverse support position lookup data
uint block_size = 1 << T;
uint pos, blk_perm;
polynomial tmp_blk, tmp_pblk;
bvector cotrace, tmp_block;
std::vector<uint> sbl1, sbl2, permuted_support;
//TODO prepare function that converts a support zero to ciphertext
//position
tmp_blk.resize (block_size);
tmp_pblk.resize (block_size);
Hc.resize (fld.m);
for (i = 0; i < fld.m; ++i) {
Hc[i].resize (block_count);
}
permuted_support.resize (block_size * block_count);
sbl1.resize (block_size);
sbl2.resize (block_size);
//go through all the blocks of original H and convert them if they
//aren't discarded.
for (i = 0; i < (fld.n / 2) / block_size; ++i) {
pos = block_perm[i];
if (pos >= block_count) continue; //was discarded
blk_perm = block_perms[pos];
pos = hperm[pos];
//permute i-th block of H to pos-th block of Hc,
//also move the support.
for (j = 0; j < block_size; ++j) {
tmp_blk[j] = Hsig[j + i * block_size];
sbl1[j] = support[j + i * block_size];
}
permutation::permute_dyadic (blk_perm, tmp_blk, tmp_pblk);
permutation::permute_dyadic (blk_perm, sbl1, sbl2);
//store support to permuted support
for (j = 0; j < block_size; ++j)
permuted_support[j + pos * block_size] = sbl2[j];
//cotrace permuted H block to Hc
cotrace.from_poly_cotrace (tmp_pblk, fld);
for (j = 0; j < fld.m; ++j)
cotrace.get_block (j * block_size, block_size, Hc[j][pos]);
}
//convert the support result to actual lookup
support_pos.clear();
//fld.n in support lookup means that it isn't there (we don't have -1)
support_pos.resize (fld.n, fld.n);
for (i = 0; i < block_size * block_count; ++i)
support_pos[permuted_support[i]] = i;
for (i = 0; i < support_pos.size(); ++i) {
std::cout << "support " << i << " has position " << support_pos[i] << std::endl;
}
//goppa polynomial
g.clear();
@ -372,7 +432,7 @@ int privkey::prepare()
polynomial tmp;
tmp.resize (2, 1);
uint t = 1 << T;
for (uint i = 0; i < t; ++i) {
for (i = 0; i < t; ++i) {
tmp[0] = fld.inv (Hsig[i]);
g.mult (tmp, fld);
}
@ -451,15 +511,13 @@ int privkey::decrypt (const bvector & in, bvector & out)
uint i, j, k;
synd_vec.resize (block_size * fld.m);
hp.resize (block_size);
cp.resize (block_size);
res.resize (block_size);
for (i = 0; i < block_count; ++i) {
in.get_block (i * block_size, block_size, cp);
for (j = 0; j < fld.m; ++j) {
Hc[j].get_block (i * block_size, block_size, hp);
fwht_dyadic_multiply (hp, cp, res);
fwht_dyadic_multiply (Hc[j][i], cp, res);
synd_vec.add_offset (res, j * block_size);
}
}
@ -475,10 +533,12 @@ int privkey::decrypt (const bvector & in, bvector & out)
//TODO evaluator should return error positions, not bvector. fix it everywhere!
out = in;
out.resize (plain_size() );
//flip error positions of out.
for (i = 0; i < ev.size(); ++i) if (ev[i]) {
if (support_pos[i] == -1) return 1; //couldn't decode TODO is it true?
out[i] = !out[i];
if (support_pos[i] == fld.n) return 1; //couldn't decode TODO is it true?
if (i < plain_size() )
out[i] = !out[i];
}
return 0;