AgreementUtilities.cs :  » PDF » iTextSharp » Org » BouncyCastle » Security » C# / CSharp Open Source

using System.Collections;
using System.Globalization;

using Org.BouncyCastle.Asn1;
using Org.BouncyCastle.Asn1.X9;
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Agreement;
using Org.BouncyCastle.Crypto.Agreement.Kdf;
using Org.BouncyCastle.Crypto.Digests;

namespace Org.BouncyCastle.Security{
  /// <remarks>
  ///  Utility class for creating IBasicAgreement objects from their names/Oids
  /// </remarks>
  public sealed class AgreementUtilities
  {
    private AgreementUtilities()
    {
    }

    private static readonly Hashtable algorithms = new Hashtable();
    //    private static readonly Hashtable oids = new Hashtable();

    static AgreementUtilities()
    {
      //algorithms[X9ObjectIdentifiers.DHSinglePassCofactorDHSha1KdfScheme.Id] = ?;
      algorithms[X9ObjectIdentifiers.DHSinglePassStdDHSha1KdfScheme.Id] = "ECDHWITHSHA1KDF";
      algorithms[X9ObjectIdentifiers.MqvSinglePassSha1KdfScheme.Id] = "ECMQVWITHSHA1KDF";
    }

    public static IBasicAgreement GetBasicAgreement(
      DerObjectIdentifier oid)
    {
      return GetBasicAgreement(oid.Id);
    }

    public static IBasicAgreement GetBasicAgreement(
      string algorithm)
    {
      string upper = algorithm.ToUpper(CultureInfo.InvariantCulture);
      string mechanism = (string) algorithms[upper];

      if (mechanism == null)
      {
        mechanism = upper;
      }

      switch (mechanism)
      {
        case "DH":
        case "DIFFIEHELLMAN":
          return new DHBasicAgreement();
        case "ECDH":
          return new ECDHBasicAgreement();
        case "ECDHC":
          return new ECDHCBasicAgreement();
        case "ECMQV":
          return new ECMqvBasicAgreement();
      }

      throw new SecurityUtilityException("Basic Agreement " + algorithm + " not recognised.");
    }

    public static IBasicAgreement GetBasicAgreementWithKdf(
      DerObjectIdentifier oid,
      string        wrapAlgorithm)
    {
      return GetBasicAgreementWithKdf(oid.Id, wrapAlgorithm);
    }

    public static IBasicAgreement GetBasicAgreementWithKdf(
      string agreeAlgorithm,
      string wrapAlgorithm)
    {
      string upper = agreeAlgorithm.ToUpper(CultureInfo.InvariantCulture);
      string mechanism = (string) algorithms[upper];

      if (mechanism == null)
      {
        mechanism = upper;
      }

      switch (mechanism)
      {
        // 'DHWITHSHA1KDF' retained for backward compatibility
        case "DHWITHSHA1KDF":
        case "ECDHWITHSHA1KDF":
          return new ECDHWithKdfBasicAgreement(
            wrapAlgorithm,
            new ECDHKekGenerator(
              new Sha1Digest()));
        case "ECMQVWITHSHA1KDF":
          return new ECMqvWithKdfBasicAgreement(
            wrapAlgorithm,
            new ECDHKekGenerator(
              new Sha1Digest()));
      }

      throw new SecurityUtilityException("Basic Agreement (with KDF) " + agreeAlgorithm + " not recognised.");
    }

    public static string GetAlgorithmName(
      DerObjectIdentifier oid)
    {
      return (string) algorithms[oid.Id];
    }
  }
}