Inheritance: DerSet
			public override void Close()
			{
				_out.Close();

				// TODO Parent context(s) should really be be closed explicitly

				_eiGen.Close();

                if (_outer.unprotectedAttributeGenerator != null)
                {
                    Asn1.Cms.AttributeTable attrTable = _outer.unprotectedAttributeGenerator.GetAttributes(Platform.CreateHashtable());

                    Asn1Set unprotectedAttrs = new BerSet(attrTable.ToAsn1EncodableVector());

                    _envGen.AddObject(new DerTaggedObject(false, 1, unprotectedAttrs));
                }

				_envGen.Close();
				_cGen.Close();
				base.Close();
			}
        /// <summary>
        /// Generate an enveloped object that contains a CMS Enveloped Data
        /// object using the passed in key generator.
        /// </summary>
        private CmsEnvelopedData Generate(
            CmsProcessable		content,
            string				encryptionOid,
            CipherKeyGenerator	keyGen)
        {
            AlgorithmIdentifier encAlgId = null;
            KeyParameter encKey;
            Asn1OctetString encContent;

            try
            {
                byte[] encKeyBytes = keyGen.GenerateKey();
                encKey = ParameterUtilities.CreateKeyParameter(encryptionOid, encKeyBytes);

                Asn1Encodable asn1Params = GenerateAsn1Parameters(encryptionOid, encKeyBytes);

                ICipherParameters cipherParameters;
                encAlgId = GetAlgorithmIdentifier(
                    encryptionOid, encKey, asn1Params, out cipherParameters);

                IBufferedCipher cipher = CipherUtilities.GetCipher(encryptionOid);
                cipher.Init(true, new ParametersWithRandom(cipherParameters, rand));

                MemoryStream bOut = new MemoryStream();
                CipherStream cOut = new CipherStream(bOut, null, cipher);

                content.Write(cOut);

                cOut.Dispose();

                encContent = new BerOctetString(bOut.ToArray());
            }
            catch (SecurityUtilityException e)
            {
                throw new CmsException("couldn't create cipher.", e);
            }
            catch (InvalidKeyException e)
            {
                throw new CmsException("key invalid in message.", e);
            }
            catch (IOException e)
            {
                throw new CmsException("exception decoding algorithm parameters.", e);
            }

            Asn1EncodableVector recipientInfos = new Asn1EncodableVector();

            foreach (RecipientInfoGenerator rig in recipientInfoGenerators)
            {
                try
                {
                    recipientInfos.Add(rig.Generate(encKey, rand));
                }
                catch (InvalidKeyException e)
                {
                    throw new CmsException("key inappropriate for algorithm.", e);
                }
                catch (GeneralSecurityException e)
                {
                    throw new CmsException("error making encrypted content.", e);
                }
            }

            EncryptedContentInfo eci = new EncryptedContentInfo(
                CmsObjectIdentifiers.Data,
                encAlgId,
                encContent);

            Asn1Set unprotectedAttrSet = null;
            if (unprotectedAttributeGenerator != null)
            {
                Asn1.Cms.AttributeTable attrTable = unprotectedAttributeGenerator.GetAttributes(Platform.CreateHashtable());

                unprotectedAttrSet = new BerSet(attrTable.ToAsn1EncodableVector());
            }

            ContentInfo contentInfo = new ContentInfo(
                CmsObjectIdentifiers.EnvelopedData,
                new EnvelopedData(null, new DerSet(recipientInfos), eci, unprotectedAttrSet));

            return new CmsEnvelopedData(contentInfo);
        }