context: using System;
  using System.Collections;
  using System.IO;
  
  using Org.BouncyCastle.Asn1;
  using Org.BouncyCastle.Asn1.Cms;
  using Org.BouncyCastle.Asn1.Kisa;
  using Org.BouncyCastle.Asn1.Nist;
  using Org.BouncyCastle.Asn1.Ntt;
  using Org.BouncyCastle.Asn1.Pkcs;
  using Org.BouncyCastle.Asn1.X509;
  using Org.BouncyCastle.Asn1.X9;
  using Org.BouncyCastle.Crypto;
  using Org.BouncyCastle.Crypto.Parameters;
  using Org.BouncyCastle.Math;
  using Org.BouncyCastle.Security;
  using Org.BouncyCastle.X509;
  
  namespace Org.BouncyCastle.Cms
  {
  	/**
  	* General class for generating a CMS enveloped-data message.
  	*
  	* A simple example of usage.
  	*
  	* <pre>
  	*      CMSEnvelopedDataGenerator  fact = new CMSEnvelopedDataGenerator();
  	*
  	*      fact.addKeyTransRecipient(cert);
  	*
  	*      CMSEnvelopedData         data = fact.generate(content, algorithm, "BC");
  	* </pre>
  	*/
  	public class CmsEnvelopedGenerator
  	{
  		internal static readonly short[] rc2Table =
  		{
  			0xbd, 0x56, 0xea, 0xf2, 0xa2, 0xf1, 0xac, 0x2a, 0xb0, 0x93, 0xd1, 0x9c, 0x1b, 0x33, 0xfd, 0xd0,
  			0x30, 0x04, 0xb6, 0xdc, 0x7d, 0xdf, 0x32, 0x4b, 0xf7, 0xcb, 0x45, 0x9b, 0x31, 0xbb, 0x21, 0x5a,
  			0x41, 0x9f, 0xe1, 0xd9, 0x4a, 0x4d, 0x9e, 0xda, 0xa0, 0x68, 0x2c, 0xc3, 0x27, 0x5f, 0x80, 0x36,
  			0x3e, 0xee, 0xfb, 0x95, 0x1a, 0xfe, 0xce, 0xa8, 0x34, 0xa9, 0x13, 0xf0, 0xa6, 0x3f, 0xd8, 0x0c,
  			0x78, 0x24, 0xaf, 0x23, 0x52, 0xc1, 0x67, 0x17, 0xf5, 0x66, 0x90, 0xe7, 0xe8, 0x07, 0xb8, 0x60,
  			0x48, 0xe6, 0x1e, 0x53, 0xf3, 0x92, 0xa4, 0x72, 0x8c, 0x08, 0x15, 0x6e, 0x86, 0x00, 0x84, 0xfa,
  			0xf4, 0x7f, 0x8a, 0x42, 0x19, 0xf6, 0xdb, 0xcd, 0x14, 0x8d, 0x50, 0x12, 0xba, 0x3c, 0x06, 0x4e,
  			0xec, 0xb3, 0x35, 0x11, 0xa1, 0x88, 0x8e, 0x2b, 0x94, 0x99, 0xb7, 0x71, 0x74, 0xd3, 0xe4, 0xbf,
  			0x3a, 0xde, 0x96, 0x0e, 0xbc, 0x0a, 0xed, 0x77, 0xfc, 0x37, 0x6b, 0x03, 0x79, 0x89, 0x62, 0xc6,
  			0xd7, 0xc0, 0xd2, 0x7c, 0x6a, 0x8b, 0x22, 0xa3, 0x5b, 0x05, 0x5d, 0x02, 0x75, 0xd5, 0x61, 0xe3,
  			0x18, 0x8f, 0x55, 0x51, 0xad, 0x1f, 0x0b, 0x5e, 0x85, 0xe5, 0xc2, 0x57, 0x63, 0xca, 0x3d, 0x6c,
  			0xb4, 0xc5, 0xcc, 0x70, 0xb2, 0x91, 0x59, 0x0d, 0x47, 0x20, 0xc8, 0x4f, 0x58, 0xe0, 0x01, 0xe2,
  			0x16, 0x38, 0xc4, 0x6f, 0x3b, 0x0f, 0x65, 0x46, 0xbe, 0x7e, 0x2d, 0x7b, 0x82, 0xf9, 0x40, 0xb5,
  			0x1d, 0x73, 0xf8, 0xeb, 0x26, 0xc7, 0x87, 0x97, 0x25, 0x54, 0xb1, 0x28, 0xaa, 0x98, 0x9d, 0xa5,
  			0x64, 0x6d, 0x7a, 0xd4, 0x10, 0x81, 0x44, 0xef, 0x49, 0xd6, 0xae, 0x2e, 0xdd, 0x76, 0x5c, 0x2f,
  			0xa7, 0x1c, 0xc9, 0x09, 0x69, 0x9a, 0x83, 0xcf, 0x29, 0x39, 0xb9, 0xe9, 0x4c, 0xff, 0x43, 0xab
  		};
  
  		internal static readonly short[] rc2Ekb =
  		{
  			0x5d, 0xbe, 0x9b, 0x8b, 0x11, 0x99, 0x6e, 0x4d, 0x59, 0xf3, 0x85, 0xa6, 0x3f, 0xb7, 0x83, 0xc5,
  			0xe4, 0x73, 0x6b, 0x3a, 0x68, 0x5a, 0xc0, 0x47, 0xa0, 0x64, 0x34, 0x0c, 0xf1, 0xd0, 0x52, 0xa5,
  			0xb9, 0x1e, 0x96, 0x43, 0x41, 0xd8, 0xd4, 0x2c, 0xdb, 0xf8, 0x07, 0x77, 0x2a, 0xca, 0xeb, 0xef,
  			0x10, 0x1c, 0x16, 0x0d, 0x38, 0x72, 0x2f, 0x89, 0xc1, 0xf9, 0x80, 0xc4, 0x6d, 0xae, 0x30, 0x3d,
  			0xce, 0x20, 0x63, 0xfe, 0xe6, 0x1a, 0xc7, 0xb8, 0x50, 0xe8, 0x24, 0x17, 0xfc, 0x25, 0x6f, 0xbb,
  			0x6a, 0xa3, 0x44, 0x53, 0xd9, 0xa2, 0x01, 0xab, 0xbc, 0xb6, 0x1f, 0x98, 0xee, 0x9a, 0xa7, 0x2d,
  			0x4f, 0x9e, 0x8e, 0xac, 0xe0, 0xc6, 0x49, 0x46, 0x29, 0xf4, 0x94, 0x8a, 0xaf, 0xe1, 0x5b, 0xc3,
  			0xb3, 0x7b, 0x57, 0xd1, 0x7c, 0x9c, 0xed, 0x87, 0x40, 0x8c, 0xe2, 0xcb, 0x93, 0x14, 0xc9, 0x61,
  			0x2e, 0xe5, 0xcc, 0xf6, 0x5e, 0xa8, 0x5c, 0xd6, 0x75, 0x8d, 0x62, 0x95, 0x58, 0x69, 0x76, 0xa1,
  			0x4a, 0xb5, 0x55, 0x09, 0x78, 0x33, 0x82, 0xd7, 0xdd, 0x79, 0xf5, 0x1b, 0x0b, 0xde, 0x26, 0x21,
  			0x28, 0x74, 0x04, 0x97, 0x56, 0xdf, 0x3c, 0xf0, 0x37, 0x39, 0xdc, 0xff, 0x06, 0xa4, 0xea, 0x42,
  			0x08, 0xda, 0xb4, 0x71, 0xb0, 0xcf, 0x12, 0x7a, 0x4e, 0xfa, 0x6c, 0x1d, 0x84, 0x00, 0xc8, 0x7f,
  			0x91, 0x45, 0xaa, 0x2b, 0xc2, 0xb1, 0x8f, 0xd5, 0xba, 0xf2, 0xad, 0x19, 0xb2, 0x67, 0x36, 0xf7,
  			0x0f, 0x0a, 0x92, 0x7d, 0xe3, 0x9d, 0xe9, 0x90, 0x3e, 0x23, 0x27, 0x66, 0x13, 0xec, 0x81, 0x15,
  			0xbd, 0x22, 0xbf, 0x9f, 0x7e, 0xa9, 0x51, 0x4b, 0x4c, 0xfb, 0x02, 0xd3, 0x70, 0x86, 0x31, 0xe7,
  			0x3b, 0x05, 0x03, 0x54, 0x60, 0x48, 0x65, 0x18, 0xd2, 0xcd, 0x5f, 0x32, 0x88, 0x0e, 0x35, 0xfd
  		};
  
  
  		// TODO Create named constants for all of these
  		public static readonly string DesEde3Cbc		= PkcsObjectIdentifiers.DesEde3Cbc.Id;
  		public static readonly string RC2Cbc			= PkcsObjectIdentifiers.RC2Cbc.Id;
  		public const string IdeaCbc						= "1.3.6.1.4.1.188.7.1.1.2";
  		public const string Cast5Cbc					= "1.2.840.113533.7.66.10";
  		public static readonly string Aes128Cbc			= NistObjectIdentifiers.IdAes128Cbc.Id;
  		public static readonly string Aes192Cbc			= NistObjectIdentifiers.IdAes192Cbc.Id;
  		public static readonly string Aes256Cbc			= NistObjectIdentifiers.IdAes256Cbc.Id;
  		public static readonly string Camellia128Cbc	= NttObjectIdentifiers.IdCamellia128Cbc.Id;
  		public static readonly string Camellia192Cbc	= NttObjectIdentifiers.IdCamellia192Cbc.Id;
  		public static readonly string Camellia256Cbc	= NttObjectIdentifiers.IdCamellia256Cbc.Id;
  		public static readonly string SeedCbc			= KisaObjectIdentifiers.IdSeedCbc.Id;
  
  		public static readonly string DesEde3Wrap		= PkcsObjectIdentifiers.IdAlgCms3DesWrap.Id;
  		public static readonly string Aes128Wrap		= NistObjectIdentifiers.IdAes128Wrap.Id;
  		public static readonly string Aes192Wrap		= NistObjectIdentifiers.IdAes192Wrap.Id;
  		public static readonly string Aes256Wrap		= NistObjectIdentifiers.IdAes256Wrap.Id;
  		public static readonly string Camellia128Wrap	= NttObjectIdentifiers.IdCamellia128Wrap.Id;
  		public static readonly string Camellia192Wrap	= NttObjectIdentifiers.IdCamellia192Wrap.Id;
  		public static readonly string Camellia256Wrap	= NttObjectIdentifiers.IdCamellia256Wrap.Id;
  		public static readonly string SeedWrap			= KisaObjectIdentifiers.IdNpkiAppCmsSeedWrap.Id;
  
  		public static readonly string ECDHSha1Kdf		= X9ObjectIdentifiers.DHSinglePassStdDHSha1KdfScheme.Id;
  
  		private static readonly CmsEnvelopedHelper Helper = CmsEnvelopedHelper.Instance;
  
  		internal IList recipientInfs = new ArrayList();
  		internal SecureRandom rand = new SecureRandom();
  
  		protected class RecipientInf
  		{
  			private readonly X509Certificate		cert;
  			private AlgorithmIdentifier	keyEncAlg;
  			private readonly AsymmetricKeyParameter	pubKey;
  			private readonly Asn1OctetString		subKeyId;
  
  			private readonly string			secKeyAlgorithm;
  			private readonly KeyParameter	secKey;
  			private readonly KekIdentifier	secKeyId;
  
  			private readonly OriginatorIdentifierOrKey	originator;
  			private const Asn1OctetString ukm = null;
  
  			private readonly AlgorithmIdentifier derivationAlg;
  
  			internal RecipientInf(
  				X509Certificate cert)
  			{
  				this.cert = cert;
  				this.pubKey = cert.GetPublicKey();
  
  				try
  				{
  					TbsCertificateStructure tbs = TbsCertificateStructure.GetInstance(
  						Asn1Object.FromByteArray(cert.GetTbsCertificate()));
  
  					keyEncAlg = tbs.SubjectPublicKeyInfo.AlgorithmID;
  				}
  //				catch (IOException e)
  				catch (Exception)
  				{
  					throw new ArgumentException("can't extract key algorithm from this cert");
  				}
  //				catch (CertificateEncodingException)
  //				{
  //					throw new ArgumentException("can't extract tbs structure from this cert");
  //				}
  			}
  
  			internal RecipientInf(
  				AsymmetricKeyParameter	pubKey,
  				Asn1OctetString			subKeyId)
  			{
  				this.pubKey = pubKey;
  				this.subKeyId = subKeyId;
  
  				try
  				{
  					SubjectPublicKeyInfo info = SubjectPublicKeyInfoFactory.CreateSubjectPublicKeyInfo(pubKey);
  
  					keyEncAlg = info.AlgorithmID;
  				}
  				catch (IOException)
  				{
  					throw new ArgumentException("can't extract key algorithm from this key");
  				}
  			}
  
  			internal RecipientInf(
  				string			secKeyAlgorithm, // TODO Can get this from secKey?
  				KeyParameter	secKey,
  				KekIdentifier	secKeyId)
  			{
  				this.secKeyAlgorithm = secKeyAlgorithm;
  				this.secKey = secKey;
  				this.secKeyId = secKeyId;
  
  				if (secKeyAlgorithm.StartsWith("DES"))
  				{
  					keyEncAlg = new AlgorithmIdentifier(
  						PkcsObjectIdentifiers.IdAlgCms3DesWrap,
  						DerNull.Instance);
  				}
  				else if (secKeyAlgorithm.StartsWith("RC2"))
  				{
  					keyEncAlg = new AlgorithmIdentifier(
  						PkcsObjectIdentifiers.IdAlgCmsRC2Wrap,
  						new DerInteger(58));
  				}
  				else if (secKeyAlgorithm.StartsWith("AES"))
  				{
  					int length = secKey.GetKey().Length * 8;
  					DerObjectIdentifier wrapOid;
  
  					if (length == 128)
  					{
  						wrapOid = NistObjectIdentifiers.IdAes128Wrap;
  					}
  					else if (length == 192)
  					{
  						wrapOid = NistObjectIdentifiers.IdAes192Wrap;
  					}
  					else if (length == 256)
  					{
  						wrapOid = NistObjectIdentifiers.IdAes256Wrap;
  					}
  					else
  					{
  						throw new ArgumentException("illegal keysize in AES");
  					}
  
  					keyEncAlg = new AlgorithmIdentifier(wrapOid);  // parameters absent
  				}
  				else if (secKeyAlgorithm.StartsWith("SEED"))
  				{
  					// parameters absent
  					keyEncAlg = new AlgorithmIdentifier(KisaObjectIdentifiers.IdNpkiAppCmsSeedWrap);
  				}
  				else if (secKeyAlgorithm.StartsWith("CAMELLIA"))
  				{
  					int length = secKey.GetKey().Length * 8;
  					DerObjectIdentifier wrapOid;
  
  					if (length == 128)
  					{
  						wrapOid = NttObjectIdentifiers.IdCamellia128Wrap;
  					}
  					else if (length == 192)
  					{
  						wrapOid = NttObjectIdentifiers.IdCamellia192Wrap;
  					}
  					else if (length == 256)
  					{
  						wrapOid = NttObjectIdentifiers.IdCamellia256Wrap;
  					}
  					else
  					{
  						throw new ArgumentException("illegal keysize in Camellia");
  					}
  
  					keyEncAlg = new AlgorithmIdentifier(wrapOid); // parameters must be absent
  				}
  				else
  				{
  					throw new ArgumentException("unknown algorithm");
  				}
  			}
  
  			public RecipientInf(
  				string						secKeyAlgorithm, // TODO Can get this from secKey?
  				KeyParameter				secKey,
  				string						algorithm,
  				string						wrapOid,
  				OriginatorIdentifierOrKey	originator,
  				X509Certificate				cert)
  			{
  				DerSequence paramSeq = new DerSequence(
  					new DerObjectIdentifier(wrapOid),
  					DerNull.Instance);
  
  				this.secKeyAlgorithm = secKeyAlgorithm;
  				this.secKey = secKey;
  				this.keyEncAlg = new AlgorithmIdentifier(new DerObjectIdentifier(algorithm), paramSeq);
  				this.originator = originator;
  				this.cert = cert;
  			}
  
  			public RecipientInf(
  				string				secKeyAlgorithm, // TODO Can get this from secKey?
  				KeyParameter		secKey,
  				AlgorithmIdentifier	derivationAlg)
  			{
  				this.secKeyAlgorithm = secKeyAlgorithm;
  				this.secKey = secKey;
  				this.derivationAlg = derivationAlg;
  			}
  
  			internal RecipientInfo ToRecipientInfo(
  				KeyParameter	key)
  			{
  				byte[] keyBytes = key.GetKey();
  
  				if (pubKey != null)
  				{
  					IWrapper keyWrapper = Helper.CreateWrapper(keyEncAlg.ObjectID.Id);
  
  					keyWrapper.Init(true, pubKey);
  
  					Asn1OctetString encKey = new DerOctetString(
  						keyWrapper.Wrap(keyBytes, 0, keyBytes.Length));
  
  					RecipientIdentifier recipId;
  					if (cert != null)
  					{
  						TbsCertificateStructure tbs = TbsCertificateStructure.GetInstance(
  							Asn1Object.FromByteArray(cert.GetTbsCertificate()));
  
  						Asn1.Cms.IssuerAndSerialNumber encSid = new Asn1.Cms.IssuerAndSerialNumber(
  							tbs.Issuer, tbs.SerialNumber.Value);
  
  						recipId = new RecipientIdentifier(encSid);
  					}
  					else
  					{
  						recipId = new RecipientIdentifier(subKeyId);
  					}
  
  					return new RecipientInfo(new KeyTransRecipientInfo(recipId, keyEncAlg, encKey));
  				}
  				else if (originator != null)
  				{
  					IWrapper keyWrapper = Helper.CreateWrapper(
  						DerObjectIdentifier.GetInstance(
  							Asn1Sequence.GetInstance(keyEncAlg.Parameters)[0]).Id);
  
  					keyWrapper.Init(true, secKey);
  
  					Asn1OctetString encKey = new DerOctetString(
  						keyWrapper.Wrap(keyBytes, 0, keyBytes.Length));
  
  					RecipientEncryptedKey rKey = new RecipientEncryptedKey(
  						new KeyAgreeRecipientIdentifier(
  							new Asn1.Cms.IssuerAndSerialNumber(
  								PrincipalUtilities.GetIssuerX509Principal(cert),
  								cert.SerialNumber)),
  						encKey);
  
  					return new RecipientInfo(
  						new KeyAgreeRecipientInfo(originator, ukm, keyEncAlg, new DerSequence(rKey)));
  				}
  				else if (derivationAlg != null)
  				{
  					string rfc3211WrapperName = Helper.GetRfc3211WrapperName(secKeyAlgorithm);
  					IWrapper keyWrapper = Helper.CreateWrapper(rfc3211WrapperName);
  
  
  					// Note: In Java build, the IV is automatically generated in JCE layer
  					int ivLength = rfc3211WrapperName.StartsWith("DESEDE") ? 8 : 16;
  					byte[] iv = SecureRandom.GetSeed(ivLength);
  
  
  					ICipherParameters parameters = new ParametersWithIV(secKey, iv);
  					keyWrapper.Init(true, parameters);
  
  					Asn1OctetString encKey = new DerOctetString(
  						keyWrapper.Wrap(keyBytes, 0, keyBytes.Length));
  
  //					byte[] iv = keyWrapper.GetIV();
  
  					DerSequence seq = new DerSequence(
  						new DerObjectIdentifier(secKeyAlgorithm),
  						new DerOctetString(iv));
  
  					keyEncAlg = new AlgorithmIdentifier(PkcsObjectIdentifiers.IdAlgPwriKek, seq);
  
  					return new RecipientInfo(new PasswordRecipientInfo(derivationAlg, keyEncAlg, encKey));
  				}
  				else
  				{
  					IWrapper keyWrapper = Helper.CreateWrapper(keyEncAlg.ObjectID.Id);
  
  					keyWrapper.Init(true, secKey);
  
  					Asn1OctetString encKey = new DerOctetString(
  						keyWrapper.Wrap(keyBytes, 0, keyBytes.Length));
  
  					return new RecipientInfo(new KekRecipientInfo(secKeyId, keyEncAlg, encKey));
  				}
  			}
  		}
  
  		/**
  		* base constructor
  		*/
  		public CmsEnvelopedGenerator()
  		{
  		}
  
  		/**
  		 * add a recipient.
  		 *
  		 * @param cert recipient's public key certificate
  		 * @exception ArgumentException if there is a problem with the certificate
  		 */
  		public void AddKeyTransRecipient(
  			X509Certificate cert)
  		{
  			recipientInfs.Add(new RecipientInf(cert));
  		}
  
  		/**
  		* add a recipient
  		*
  		* @param key the public key used by the recipient
  		* @param subKeyId the identifier for the recipient's public key
  		* @exception ArgumentException if there is a problem with the key
  		*/
  		public void AddKeyTransRecipient(
  			AsymmetricKeyParameter	pubKey,
  			byte[]					subKeyId)
  		{
  			recipientInfs.Add(new CmsEnvelopedGenerator.RecipientInf(pubKey, new DerOctetString(subKeyId)));
  		}
  
  		/**
  		* add a KEK recipient.
  		* @param key the secret key to use for wrapping
  		* @param keyIdentifier the byte string that identifies the key
  		*/
  		public void AddKekRecipient(
  			string			keyAlgorithm, // TODO Remove need for this parameter
  			KeyParameter	key,
  			byte[]			keyIdentifier)
  		{
  			recipientInfs.Add(new RecipientInf(keyAlgorithm, key, new KekIdentifier(keyIdentifier, null, null)));
  		}
  
  		public void AddPasswordRecipient(
  			CmsPbeKey	pbeKey,
  			string		kekAlgorithmOid)
  		{
  			Pbkdf2Params p = new Pbkdf2Params(pbeKey.Salt, pbeKey.IterationCount);
  
gt: 			KeyParameter secretKey = pbeKey.GetEncoded(kekAlgorithmOid);