1 files changed, 151 insertions, 0 deletions
diff --git a/libraries/spongycastle/core/src/main/java/org/spongycastle/pqc/crypto/mceliece/McElieceKeyPairGenerator.java b/libraries/spongycastle/core/src/main/java/org/spongycastle/pqc/crypto/mceliece/McElieceKeyPairGenerator.java
new file mode 100644
index 000000000..07db4cd6d
--- /dev/null
+++ b/libraries/spongycastle/core/src/main/java/org/spongycastle/pqc/crypto/mceliece/McElieceKeyPairGenerator.java
@@ -0,0 +1,151 @@
+package org.spongycastle.pqc.crypto.mceliece;
+
+import java.security.SecureRandom;
+
+import org.spongycastle.crypto.AsymmetricCipherKeyPair;
+import org.spongycastle.crypto.AsymmetricCipherKeyPairGenerator;
+import org.spongycastle.crypto.KeyGenerationParameters;
+import org.spongycastle.pqc.math.linearalgebra.GF2Matrix;
+import org.spongycastle.pqc.math.linearalgebra.GF2mField;
+import org.spongycastle.pqc.math.linearalgebra.GoppaCode;
+import org.spongycastle.pqc.math.linearalgebra.GoppaCode.MaMaPe;
+import org.spongycastle.pqc.math.linearalgebra.Permutation;
+import org.spongycastle.pqc.math.linearalgebra.PolynomialGF2mSmallM;
+import org.spongycastle.pqc.math.linearalgebra.PolynomialRingGF2m;
+
+
+/**
+ * This class implements key pair generation of the McEliece Public Key
+ * Cryptosystem (McEliecePKC).
+ */
+public class McElieceKeyPairGenerator
+    implements AsymmetricCipherKeyPairGenerator
+{
+
+
+    public McElieceKeyPairGenerator()
+    {
+
+    }
+
+
+    /**
+     * The OID of the algorithm.
+     */
+    private static final String OID = "1.3.6.1.4.1.8301.3.1.3.4.1";
+
+    private McElieceKeyGenerationParameters mcElieceParams;
+
+    // the extension degree of the finite field GF(2^m)
+    private int m;
+
+    // the length of the code
+    private int n;
+
+    // the error correction capability
+    private int t;
+
+    // the field polynomial
+    private int fieldPoly;
+
+    // the source of randomness
+    private SecureRandom random;
+
+    // flag indicating whether the key pair generator has been initialized
+    private boolean initialized = false;
+
+
+    /**
+     * Default initialization of the key pair generator.
+     */
+    private void initializeDefault()
+    {
+        McElieceKeyGenerationParameters mcParams = new McElieceKeyGenerationParameters(new SecureRandom(), new McElieceParameters());
+        initialize(mcParams);
+    }
+
+    private void initialize(
+        KeyGenerationParameters param)
+    {
+        this.mcElieceParams = (McElieceKeyGenerationParameters)param;
+
+        // set source of randomness
+        this.random = new SecureRandom();
+
+        this.m = this.mcElieceParams.getParameters().getM();
+        this.n = this.mcElieceParams.getParameters().getN();
+        this.t = this.mcElieceParams.getParameters().getT();
+        this.fieldPoly = this.mcElieceParams.getParameters().getFieldPoly();
+        this.initialized = true;
+    }
+
+
+    private AsymmetricCipherKeyPair genKeyPair()
+    {
+
+        if (!initialized)
+        {
+            initializeDefault();
+        }
+
+        // finite field GF(2^m)
+        GF2mField field = new GF2mField(m, fieldPoly);
+
+        // irreducible Goppa polynomial
+        PolynomialGF2mSmallM gp = new PolynomialGF2mSmallM(field, t,
+            PolynomialGF2mSmallM.RANDOM_IRREDUCIBLE_POLYNOMIAL, random);
+        PolynomialRingGF2m ring = new PolynomialRingGF2m(field, gp);
+
+        // matrix used to compute square roots in (GF(2^m))^t
+        PolynomialGF2mSmallM[] sqRootMatrix = ring.getSquareRootMatrix();
+
+        // generate canonical check matrix
+        GF2Matrix h = GoppaCode.createCanonicalCheckMatrix(field, gp);
+
+        // compute short systematic form of check matrix
+        MaMaPe mmp = GoppaCode.computeSystematicForm(h, random);
+        GF2Matrix shortH = mmp.getSecondMatrix();
+        Permutation p1 = mmp.getPermutation();
+
+        // compute short systematic form of generator matrix
+        GF2Matrix shortG = (GF2Matrix)shortH.computeTranspose();
+
+        // extend to full systematic form
+        GF2Matrix gPrime = shortG.extendLeftCompactForm();
+
+        // obtain number of rows of G (= dimension of the code)
+        int k = shortG.getNumRows();
+
+        // generate random invertible (k x k)-matrix S and its inverse S^-1
+        GF2Matrix[] matrixSandInverse = GF2Matrix
+            .createRandomRegularMatrixAndItsInverse(k, random);
+
+        // generate random permutation P2
+        Permutation p2 = new Permutation(n, random);
+
+        // compute public matrix G=S*G'*P2
+        GF2Matrix g = (GF2Matrix)matrixSandInverse[0].rightMultiply(gPrime);
+        g = (GF2Matrix)g.rightMultiply(p2);
+
+
+        // generate keys
+        McEliecePublicKeyParameters pubKey = new McEliecePublicKeyParameters(OID, n, t, g, mcElieceParams.getParameters());
+        McEliecePrivateKeyParameters privKey = new McEliecePrivateKeyParameters(OID, n, k,
+            field, gp, matrixSandInverse[1], p1, p2, h, sqRootMatrix, mcElieceParams.getParameters());
+
+        // return key pair
+        return new AsymmetricCipherKeyPair(pubKey, privKey);
+    }
+
+    public void init(KeyGenerationParameters param)
+    {
+        this.initialize(param);
+
+    }
+
+    public AsymmetricCipherKeyPair generateKeyPair()
+    {
+        return genKeyPair();
+    }
+
+}