1 files changed, 153 insertions, 0 deletions
diff --git a/core/src/main/java/org/spongycastle/pqc/math/ntru/polynomial/ProductFormPolynomial.java b/core/src/main/java/org/spongycastle/pqc/math/ntru/polynomial/ProductFormPolynomial.java
new file mode 100644
index 00000000..e60ce8b8
--- /dev/null
+++ b/core/src/main/java/org/spongycastle/pqc/math/ntru/polynomial/ProductFormPolynomial.java
@@ -0,0 +1,153 @@
+package org.spongycastle.pqc.math.ntru.polynomial;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.security.SecureRandom;
+
+import org.spongycastle.util.Arrays;
+
+/**
+ * A polynomial of the form <code>f1*f2+f3</code>, where
+ * <code>f1,f2,f3</code> are very sparsely populated ternary polynomials.
+ */
+public class ProductFormPolynomial
+    implements Polynomial
+{
+    private SparseTernaryPolynomial f1, f2, f3;
+
+    public ProductFormPolynomial(SparseTernaryPolynomial f1, SparseTernaryPolynomial f2, SparseTernaryPolynomial f3)
+    {
+        this.f1 = f1;
+        this.f2 = f2;
+        this.f3 = f3;
+    }
+
+    public static ProductFormPolynomial generateRandom(int N, int df1, int df2, int df3Ones, int df3NegOnes, SecureRandom random)
+    {
+        SparseTernaryPolynomial f1 = SparseTernaryPolynomial.generateRandom(N, df1, df1, random);
+        SparseTernaryPolynomial f2 = SparseTernaryPolynomial.generateRandom(N, df2, df2, random);
+        SparseTernaryPolynomial f3 = SparseTernaryPolynomial.generateRandom(N, df3Ones, df3NegOnes, random);
+        return new ProductFormPolynomial(f1, f2, f3);
+    }
+
+    public static ProductFormPolynomial fromBinary(byte[] data, int N, int df1, int df2, int df3Ones, int df3NegOnes)
+        throws IOException
+    {
+        return fromBinary(new ByteArrayInputStream(data), N, df1, df2, df3Ones, df3NegOnes);
+    }
+
+    public static ProductFormPolynomial fromBinary(InputStream is, int N, int df1, int df2, int df3Ones, int df3NegOnes)
+        throws IOException
+    {
+        SparseTernaryPolynomial f1;
+
+        f1 = SparseTernaryPolynomial.fromBinary(is, N, df1, df1);
+        SparseTernaryPolynomial f2 = SparseTernaryPolynomial.fromBinary(is, N, df2, df2);
+        SparseTernaryPolynomial f3 = SparseTernaryPolynomial.fromBinary(is, N, df3Ones, df3NegOnes);
+        return new ProductFormPolynomial(f1, f2, f3);
+    }
+
+    public byte[] toBinary()
+    {
+        byte[] f1Bin = f1.toBinary();
+        byte[] f2Bin = f2.toBinary();
+        byte[] f3Bin = f3.toBinary();
+
+        byte[] all = Arrays.copyOf(f1Bin, f1Bin.length + f2Bin.length + f3Bin.length);
+        System.arraycopy(f2Bin, 0, all, f1Bin.length, f2Bin.length);
+        System.arraycopy(f3Bin, 0, all, f1Bin.length + f2Bin.length, f3Bin.length);
+        return all;
+    }
+
+    public IntegerPolynomial mult(IntegerPolynomial b)
+    {
+        IntegerPolynomial c = f1.mult(b);
+        c = f2.mult(c);
+        c.add(f3.mult(b));
+        return c;
+    }
+
+    public BigIntPolynomial mult(BigIntPolynomial b)
+    {
+        BigIntPolynomial c = f1.mult(b);
+        c = f2.mult(c);
+        c.add(f3.mult(b));
+        return c;
+    }
+
+    public IntegerPolynomial toIntegerPolynomial()
+    {
+        IntegerPolynomial i = f1.mult(f2.toIntegerPolynomial());
+        i.add(f3.toIntegerPolynomial());
+        return i;
+    }
+
+    public IntegerPolynomial mult(IntegerPolynomial poly2, int modulus)
+    {
+        IntegerPolynomial c = mult(poly2);
+        c.mod(modulus);
+        return c;
+    }
+
+    public int hashCode()
+    {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((f1 == null) ? 0 : f1.hashCode());
+        result = prime * result + ((f2 == null) ? 0 : f2.hashCode());
+        result = prime * result + ((f3 == null) ? 0 : f3.hashCode());
+        return result;
+    }
+
+    public boolean equals(Object obj)
+    {
+        if (this == obj)
+        {
+            return true;
+        }
+        if (obj == null)
+        {
+            return false;
+        }
+        if (getClass() != obj.getClass())
+        {
+            return false;
+        }
+        ProductFormPolynomial other = (ProductFormPolynomial)obj;
+        if (f1 == null)
+        {
+            if (other.f1 != null)
+            {
+                return false;
+            }
+        }
+        else if (!f1.equals(other.f1))
+        {
+            return false;
+        }
+        if (f2 == null)
+        {
+            if (other.f2 != null)
+            {
+                return false;
+            }
+        }
+        else if (!f2.equals(other.f2))
+        {
+            return false;
+        }
+        if (f3 == null)
+        {
+            if (other.f3 != null)
+            {
+                return false;
+            }
+        }
+        else if (!f3.equals(other.f3))
+        {
+            return false;
+        }
+        return true;
+    }
+}