1 files changed, 119 insertions, 0 deletions
diff --git a/libraries/spongycastle/core/src/main/java/org/spongycastle/pqc/crypto/mceliece/McElieceCCA2KeyPairGenerator.java b/libraries/spongycastle/core/src/main/java/org/spongycastle/pqc/crypto/mceliece/McElieceCCA2KeyPairGenerator.java
new file mode 100644
index 000000000..c950bda7a
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+++ b/libraries/spongycastle/core/src/main/java/org/spongycastle/pqc/crypto/mceliece/McElieceCCA2KeyPairGenerator.java
@@ -0,0 +1,119 @@
+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 McElieceCCA2KeyPairGenerator
+    implements AsymmetricCipherKeyPairGenerator
+{
+
+
+    /**
+     * The OID of the algorithm.
+     */
+    public static final String OID = "1.3.6.1.4.1.8301.3.1.3.4.2";
+
+    private McElieceCCA2KeyGenerationParameters mcElieceCCA2Params;
+
+    // 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()
+    {
+        McElieceCCA2KeyGenerationParameters mcCCA2Params = new McElieceCCA2KeyGenerationParameters(new SecureRandom(), new McElieceCCA2Parameters());
+        init(mcCCA2Params);
+    }
+
+    // TODO
+    public void init(
+        KeyGenerationParameters param)
+    {
+        this.mcElieceCCA2Params = (McElieceCCA2KeyGenerationParameters)param;
+
+        // set source of randomness
+        this.random = new SecureRandom();
+
+        this.m = this.mcElieceCCA2Params.getParameters().getM();
+        this.n = this.mcElieceCCA2Params.getParameters().getN();
+        this.t = this.mcElieceCCA2Params.getParameters().getT();
+        this.fieldPoly = this.mcElieceCCA2Params.getParameters().getFieldPoly();
+        this.initialized = true;
+    }
+
+
+    public AsymmetricCipherKeyPair generateKeyPair()
+    {
+
+        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 for computing square roots in (GF(2^m))^t
+        PolynomialGF2mSmallM[] qInv = 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 p = mmp.getPermutation();
+
+        // compute short systematic form of generator matrix
+        GF2Matrix shortG = (GF2Matrix)shortH.computeTranspose();
+
+        // obtain number of rows of G (= dimension of the code)
+        int k = shortG.getNumRows();
+
+        // generate keys
+        McElieceCCA2PublicKeyParameters pubKey = new McElieceCCA2PublicKeyParameters(OID, n, t, shortG, mcElieceCCA2Params.getParameters());
+        McElieceCCA2PrivateKeyParameters privKey = new McElieceCCA2PrivateKeyParameters(OID, n, k,
+            field, gp, p, h, qInv, mcElieceCCA2Params.getParameters());
+
+        // return key pair
+        return new AsymmetricCipherKeyPair(pubKey, privKey);
+    }
+}