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permutation: avoid needlessly precomputed hpermInv

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This commit is contained in:
Mirek Kratochvil 2014-02-02 17:18:48 +01:00
parent 9316509223
commit b566beaa38
3 changed files with 10 additions and 13 deletions
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2
src/matrix.cpp
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@ -174,7 +174,7 @@ void matrix::generate_random_with_inversion (uint size, matrix&inversion, prng&r
}
*this = lt;
this->mult (ut);
ut.compute_inversion (inversion, true, false);
ut.compute_inversion (inversion, true, false);
lt.compute_inversion (ut, false, true);
inversion.mult (ut);
}

15
src/mce.cpp
View file

@ -42,14 +42,12 @@ int mce::generate (pubkey&pub, privkey&priv, prng&rng, uint m, uint t)
S.generate_random_with_inversion (generator.height(), priv.Sinv, rng);
//scramble permutation
permutation P;
P.generate_random (generator.width(), rng);
P.compute_inversion (priv.Pinv);
priv.Pinv.generate_random (generator.width(), rng);
//public key
pub.t = t;
S.mult (generator);
P.permute (S, pub.G);
priv.Pinv.permute_inv (S, pub.G);
return 0;
}
@ -96,11 +94,8 @@ int privkey::decrypt (const bvector&in, bvector&out, bvector&errors)
Pinv.permute (in, not_permuted);
//prepare for decoding
permutation hpermInv; //TODO pre-invert it in prepare()
hperm.compute_inversion (hpermInv);
bvector canonical, syndrome;
hpermInv.permute (not_permuted, canonical);
hperm.permute_inv (not_permuted, canonical);
h.mult_vec_right (canonical, syndrome);
//decode
@ -140,7 +135,6 @@ int privkey::sign (const bvector&in, bvector&out, uint delta, uint attempts, prn
uint i, s, t;
bvector p, e, synd, synd_orig, e2;
std::vector<uint> epos;
permutation hpermInv;
polynomial loc, Synd;
s = hash_size();
@ -149,8 +143,7 @@ int privkey::sign (const bvector&in, bvector&out, uint delta, uint attempts, prn
//first, prepare the codeword to canonical form for decoding
Pinv.permute (in, e2);
hperm.compute_inversion (hpermInv);
hpermInv.permute (e2, p);
hperm.permute_inv (e2, p);
//prepare extra error vector
e.resize (s, 0);

6
src/permutation.h
View file

@ -44,12 +44,16 @@ public:
item (i) = i;
}
//TODO permute_inv is easy, do it everywhere
template<class A, class R> void permute (const A&a, R&r) const {
r.resize (a.size() );
for (uint i = 0; i < size(); ++i) r[item (i) ] = a[i];
}
template<class A, class R> void permute_inv (const A&a, R&r) const {
r.resize (a.size() );
for (uint i = 0; i < size(); ++i) r[i] = a[item (i)];
}
void permute_rows (const matrix&, matrix&) const;
//work-alike for dyadic permutations.