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

using System;
using System.IO;

using Org.BouncyCastle.Asn1;
using Org.BouncyCastle.Asn1.Cms;
using Asn1PkcsOrg.BouncyCastle.Asn1.Pkcs;
using Org.BouncyCastle.Asn1.X509;
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Security;
using Org.BouncyCastle.X509;

namespace Org.BouncyCastle.Cms{
    /**
    * the KeyTransRecipientInformation class for a recipient who has been sent a secret
    * key encrypted using their public key that needs to be used to
    * extract the message.
    */
    public class KeyTransRecipientInformation
        : RecipientInformation
    {
        private KeyTransRecipientInfo info;

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

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

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

      RecipientIdentifier r = info.RecipientIdentifier;

      try
            {
                if (r.IsTagged)
                {
                    Asn1OctetString octs = Asn1OctetString.GetInstance(r.ID);

          rid.SubjectKeyIdentifier = octs.GetOctets();
                }
                else
                {
                    IssuerAndSerialNumber iAnds = IssuerAndSerialNumber.GetInstance(r.ID);

          rid.Issuer = iAnds.Name;
                    rid.SerialNumber = iAnds.SerialNumber.Value;
                }
            }
            catch (IOException)
            {
                throw new ArgumentException("invalid rid in KeyTransRecipientInformation");
            }
        }

    private string GetExchangeEncryptionAlgorithmName(
      DerObjectIdentifier oid)
    {
      if (Asn1Pkcs.PkcsObjectIdentifiers.RsaEncryption.Equals(oid))
      {
        return "RSA//PKCS1Padding";
      }

      return oid.Id;
    }

    internal KeyParameter UnwrapKey(ICipherParameters key)
    {
      byte[] encryptedKey = info.EncryptedKey.GetOctets();
      string keyExchangeAlgorithm = GetExchangeEncryptionAlgorithmName(keyEncAlg.ObjectID);

      try
      {
        IWrapper keyWrapper = WrapperUtilities.GetWrapper(keyExchangeAlgorithm);
        keyWrapper.Init(false, key);

        // FIXME Support for MAC algorithm parameters similar to cipher parameters
        AlgorithmIdentifier alg = GetActiveAlgID();
        return ParameterUtilities.CreateKeyParameter(
          alg.ObjectID, keyWrapper.Unwrap(encryptedKey, 0, encryptedKey.Length));
      }
      catch (SecurityUtilityException e)
      {
        throw new CmsException("couldn't create cipher.", e);
      }
      catch (InvalidKeyException e)
      {
        throw new CmsException("key invalid in message.", e);
      }
//      catch (IllegalBlockSizeException e)
      catch (DataLengthException e)
      {
        throw new CmsException("illegal blocksize in message.", e);
      }
//      catch (BadPaddingException e)
      catch (InvalidCipherTextException e)
      {
        throw new CmsException("bad padding in message.", e);
      }
    }
    
    /**
        * decrypt the content and return it as a byte array.
        */
        public override CmsTypedStream GetContentStream(
            ICipherParameters key)
        {
      KeyParameter sKey = UnwrapKey(key);

      return GetContentFromSessionKey(sKey);
    }
    }
}