NISTNamedCurves.cs :  » PDF » iTextSharp » Org » BouncyCastle » Asn1 » Nist » C# / CSharp Open Source

using System;
using System.Collections;
using System.Globalization;

using Org.BouncyCastle.Asn1;
using Org.BouncyCastle.Asn1.Sec;
using Org.BouncyCastle.Asn1.X9;
using Org.BouncyCastle.Utilities.Collections;

namespace Org.BouncyCastle.Asn1.Nist{
  /**
  * Utility class for fetching curves using their NIST names as published in FIPS-PUB 186-2
  */
  public sealed class NistNamedCurves
  {
    private NistNamedCurves()
    {
    }

    private static readonly Hashtable objIds = new Hashtable();
    private static readonly Hashtable names = new Hashtable();

    private static void DefineCurve(
      string        name,
      DerObjectIdentifier  oid)
    {
      objIds.Add(name, oid);
      names.Add(oid, name);
    }

    static NistNamedCurves()
    {
      DefineCurve("B-571", SecObjectIdentifiers.SecT571r1);
      DefineCurve("B-409", SecObjectIdentifiers.SecT409r1);
      DefineCurve("B-283", SecObjectIdentifiers.SecT283r1);
      DefineCurve("B-233", SecObjectIdentifiers.SecT233r1);
      DefineCurve("B-163", SecObjectIdentifiers.SecT163r2);
      DefineCurve("P-521", SecObjectIdentifiers.SecP521r1);
      DefineCurve("P-384", SecObjectIdentifiers.SecP384r1);
      DefineCurve("P-256", SecObjectIdentifiers.SecP256r1);
      DefineCurve("P-224", SecObjectIdentifiers.SecP224r1);
      DefineCurve("P-192", SecObjectIdentifiers.SecP192r1);
    }

    public static X9ECParameters GetByName(
      string name)
    {
      DerObjectIdentifier oid = (DerObjectIdentifier) objIds[name.ToUpper(CultureInfo.InvariantCulture)];

      if (oid != null)
      {
        return GetByOid(oid);
      }

      return null;
    }

    /**
    * return the X9ECParameters object for the named curve represented by
    * the passed in object identifier. Null if the curve isn't present.
    *
    * @param oid an object identifier representing a named curve, if present.
    */
    public static X9ECParameters GetByOid(
      DerObjectIdentifier oid)
    {
      return SecNamedCurves.GetByOid(oid);
    }

    /**
    * return the object identifier signified by the passed in name. Null
    * if there is no object identifier associated with name.
    *
    * @return the object identifier associated with name, if present.
    */
    public static DerObjectIdentifier GetOid(
      string name)
    {
      return (DerObjectIdentifier) objIds[name.ToUpper(CultureInfo.InvariantCulture)];
    }

    /**
    * return the named curve name represented by the given object identifier.
    */
    public static string GetName(
      DerObjectIdentifier  oid)
    {
      return (string) names[oid];
    }

    /**
    * returns an enumeration containing the name strings for curves
    * contained in this structure.
    */
    public static IEnumerable Names
    {
      get { return new EnumerableProxy(objIds.Keys); }
    }
  }
}