Examples with Permutation com.github.zhenwei.core.pqc.math.linearalgebra.Permutation used on opensource projects

Example 6 with Permutation

use of com.github.zhenwei.core.pqc.math.linearalgebra.Permutation in project LinLong-Java by zhenwei1108.

the class McElieceCCA2Primitives method decryptionPrimitive.

public static GF2Vector[] decryptionPrimitive(McElieceCCA2PrivateKeyParameters privKey, GF2Vector c) {
    // obtain values from private key
    int k = privKey.getK();
    Permutation p = privKey.getP();
    GF2mField field = privKey.getField();
    PolynomialGF2mSmallM gp = privKey.getGoppaPoly();
    GF2Matrix h = privKey.getH();
    PolynomialGF2mSmallM[] q = privKey.getQInv();
    // compute inverse permutation P^-1
    Permutation pInv = p.computeInverse();
    // multiply c with permutation P^-1
    GF2Vector cPInv = (GF2Vector) c.multiply(pInv);
    // compute syndrome of cP^-1
    GF2Vector syndVec = (GF2Vector) h.rightMultiply(cPInv);
    // decode syndrome
    GF2Vector errors = GoppaCode.syndromeDecode(syndVec, field, gp, q);
    GF2Vector mG = (GF2Vector) cPInv.add(errors);
    // multiply codeword and error vector with P
    mG = (GF2Vector) mG.multiply(p);
    errors = (GF2Vector) errors.multiply(p);
    // extract plaintext vector (last k columns of mG)
    GF2Vector m = mG.extractRightVector(k);
    // return vectors
    return new GF2Vector[] { m, errors };
}