1 files changed, 70 insertions, 24 deletions
diff --git a/crypto/src/math/ec/ECFieldElement.cs b/crypto/src/math/ec/ECFieldElement.cs
index 3676c81b1..350e8c6d4 100644
--- a/crypto/src/math/ec/ECFieldElement.cs
+++ b/crypto/src/math/ec/ECFieldElement.cs
@@ -101,9 +101,14 @@ namespace Org.BouncyCastle.Math.EC
}
}
- public class FpFieldElement
+ public abstract class AbstractFpFieldElement
: ECFieldElement
{
+ }
+
+ public class FpFieldElement
+ : AbstractFpFieldElement
+ {
private readonly BigInteger q, r, x;
internal static BigInteger CalculateResidue(BigInteger p)
@@ -536,6 +541,45 @@ namespace Org.BouncyCastle.Math.EC
}
}
+ public abstract class AbstractF2mFieldElement
+ : ECFieldElement
+ {
+ public virtual ECFieldElement HalfTrace()
+ {
+ int m = FieldSize;
+ if ((m & 1) == 0)
+ throw new InvalidOperationException("Half-trace only defined for odd m");
+
+ ECFieldElement fe = this;
+ ECFieldElement ht = fe;
+ for (int i = 2; i < m; i += 2)
+ {
+ fe = fe.SquarePow(2);
+ ht = ht.Add(fe);
+ }
+
+ return ht;
+ }
+
+ public virtual int Trace()
+ {
+ int m = FieldSize;
+ ECFieldElement fe = this;
+ ECFieldElement tr = fe;
+ for (int i = 1; i < m; ++i)
+ {
+ fe = fe.Square();
+ tr = tr.Add(fe);
+ }
+ if (tr.IsZero)
+ return 0;
+ if (tr.IsOne)
+ return 1;
+
+ throw new InvalidOperationException("Internal error in trace calculation");
+ }
+ }
+
/**
* Class representing the Elements of the finite field
* <code>F<sub>2<sup>m</sup></sub></code> in polynomial basis (PB)
@@ -544,7 +588,7 @@ namespace Org.BouncyCastle.Math.EC
* representation is not supported.
*/
public class F2mFieldElement
- : ECFieldElement
+ : AbstractF2mFieldElement
{
/**
* Indicates gaussian normal basis representation (GNB). Number chosen
@@ -582,20 +626,21 @@ namespace Org.BouncyCastle.Math.EC
internal LongArray x;
/**
- * Constructor for Ppb.
- * @param m The exponent <code>m</code> of
- * <code>F<sub>2<sup>m</sup></sub></code>.
- * @param k1 The integer <code>k1</code> where <code>x<sup>m</sup> +
- * x<sup>k3</sup> + x<sup>k2</sup> + x<sup>k1</sup> + 1</code>
- * represents the reduction polynomial <code>f(z)</code>.
- * @param k2 The integer <code>k2</code> where <code>x<sup>m</sup> +
- * x<sup>k3</sup> + x<sup>k2</sup> + x<sup>k1</sup> + 1</code>
- * represents the reduction polynomial <code>f(z)</code>.
- * @param k3 The integer <code>k3</code> where <code>x<sup>m</sup> +
- * x<sup>k3</sup> + x<sup>k2</sup> + x<sup>k1</sup> + 1</code>
- * represents the reduction polynomial <code>f(z)</code>.
- * @param x The BigInteger representing the value of the field element.
- */
+ * Constructor for Ppb.
+ * @param m The exponent <code>m</code> of
+ * <code>F<sub>2<sup>m</sup></sub></code>.
+ * @param k1 The integer <code>k1</code> where <code>x<sup>m</sup> +
+ * x<sup>k3</sup> + x<sup>k2</sup> + x<sup>k1</sup> + 1</code>
+ * represents the reduction polynomial <code>f(z)</code>.
+ * @param k2 The integer <code>k2</code> where <code>x<sup>m</sup> +
+ * x<sup>k3</sup> + x<sup>k2</sup> + x<sup>k1</sup> + 1</code>
+ * represents the reduction polynomial <code>f(z)</code>.
+ * @param k3 The integer <code>k3</code> where <code>x<sup>m</sup> +
+ * x<sup>k3</sup> + x<sup>k2</sup> + x<sup>k1</sup> + 1</code>
+ * represents the reduction polynomial <code>f(z)</code>.
+ * @param x The BigInteger representing the value of the field element.
+ */
+ [Obsolete("Use ECCurve.FromBigInteger to construct field elements")]
public F2mFieldElement(
int m,
int k1,
@@ -627,14 +672,15 @@ namespace Org.BouncyCastle.Math.EC
}
/**
- * Constructor for Tpb.
- * @param m The exponent <code>m</code> of
- * <code>F<sub>2<sup>m</sup></sub></code>.
- * @param k The integer <code>k</code> where <code>x<sup>m</sup> +
- * x<sup>k</sup> + 1</code> represents the reduction
- * polynomial <code>f(z)</code>.
- * @param x The BigInteger representing the value of the field element.
- */
+ * Constructor for Tpb.
+ * @param m The exponent <code>m</code> of
+ * <code>F<sub>2<sup>m</sup></sub></code>.
+ * @param k The integer <code>k</code> where <code>x<sup>m</sup> +
+ * x<sup>k</sup> + 1</code> represents the reduction
+ * polynomial <code>f(z)</code>.
+ * @param x The BigInteger representing the value of the field element.
+ */
+ [Obsolete("Use ECCurve.FromBigInteger to construct field elements")]
public F2mFieldElement(
int m,
int k,
|
