KEKRecipientInformation.cs :  » PDF » iTextSharp » Org » BouncyCastle » Cms » C# / CSharp Open Source

using System;
using System.IO;

using Org.BouncyCastle.Asn1.Cms;
using Org.BouncyCastle.Asn1.X509;
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Security;

namespace Org.BouncyCastle.Cms{
    /**
    * the RecipientInfo class for a recipient who has been sent a message
    * encrypted using a secret key known to the other side.
    */
    public class KekRecipientInformation
        : RecipientInformation
    {
        private KekRecipientInfo info;

    [Obsolete]
    public KekRecipientInformation(
            KekRecipientInfo  info,
            AlgorithmIdentifier  encAlg,
            Stream        data)
      : this(info, encAlg, null, null, data)
    {
    }

    [Obsolete]
    public KekRecipientInformation(
            KekRecipientInfo  info,
            AlgorithmIdentifier  encAlg,
            AlgorithmIdentifier  macAlg,
            Stream        data)
      : this(info, encAlg, macAlg, null, data)
    {
    }

    public KekRecipientInformation(
            KekRecipientInfo  info,
            AlgorithmIdentifier  encAlg,
            AlgorithmIdentifier  macAlg,
            AlgorithmIdentifier  authEncAlg,
            Stream        data)
            : base(encAlg, macAlg, authEncAlg, info.KeyEncryptionAlgorithm, data)
        {
            this.info = info;
            this.rid = new RecipientID();

      KekIdentifier kekId = info.KekID;

      rid.KeyIdentifier = kekId.KeyIdentifier.GetOctets();
        }

    /**
        * decrypt the content and return an input stream.
        */
        public override CmsTypedStream GetContentStream(
            ICipherParameters key)
        {
      try
      {
        byte[] encryptedKey = info.EncryptedKey.GetOctets();
        IWrapper keyWrapper = WrapperUtilities.GetWrapper(keyEncAlg.ObjectID.Id);

        keyWrapper.Init(false, key);

        AlgorithmIdentifier aid = GetActiveAlgID();
        KeyParameter sKey = ParameterUtilities.CreateKeyParameter(
          aid.ObjectID, keyWrapper.Unwrap(encryptedKey, 0, encryptedKey.Length));

        return GetContentFromSessionKey(sKey);
      }
      catch (SecurityUtilityException e)
      {
        throw new CmsException("couldn't create cipher.", e);
      }
      catch (InvalidKeyException e)
      {
        throw new CmsException("key invalid in message.", e);
      }
        }
    }
}