diff options
Diffstat (limited to 'crypto/src/math/ec/ECFieldElement.cs')
| -rw-r--r-- | crypto/src/math/ec/ECFieldElement.cs | 94 |
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, |