context: using System;
  using System.Collections;
  
  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.Security;
  using Org.BouncyCastle.Utilities;
  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
  	{
  		// Note: These tables are complementary: If rc2Table[i]==j, then rc2Ekb[j]==i
  		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;
  		public static readonly string ECMqvSha1Kdf		= X9ObjectIdentifiers.MqvSinglePassSha1KdfScheme.Id;
  
  		internal readonly IList recipientInfoGenerators = Platform.CreateArrayList();
  		internal readonly SecureRandom rand;
  
          internal CmsAttributeTableGenerator unprotectedAttributeGenerator = null;
  
  		public CmsEnvelopedGenerator()
  			: this(new SecureRandom())
  		{
  		}
  
  		/// <summary>Constructor allowing specific source of randomness</summary>
  		/// <param name="rand">Instance of <c>SecureRandom</c> to use.</param>
  		public CmsEnvelopedGenerator(
  			SecureRandom rand)
  		{
  			this.rand = rand;
  		}
  
          public CmsAttributeTableGenerator UnprotectedAttributeGenerator
          {
              get { return this.unprotectedAttributeGenerator; }
              set { this.unprotectedAttributeGenerator = value; }
          }
  
  		/**
  		 * 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)
  		{
  			KeyTransRecipientInfoGenerator ktrig = new KeyTransRecipientInfoGenerator();
  			ktrig.RecipientCert = cert;
  
  			recipientInfoGenerators.Add(ktrig);
  		}
  
  		/**
  		* 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)
  		{
  			KeyTransRecipientInfoGenerator ktrig = new KeyTransRecipientInfoGenerator();
  			ktrig.RecipientPublicKey = pubKey;
  			ktrig.SubjectKeyIdentifier = new DerOctetString(subKeyId);
  
  			recipientInfoGenerators.Add(ktrig);
  		}
  
  		/**
  		 * 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)
  		{
  			AddKekRecipient(keyAlgorithm, key, new KekIdentifier(keyIdentifier, null, null));
  		}
  
  		/**
  		* 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,
  			KekIdentifier	kekIdentifier)
  		{
  			KekRecipientInfoGenerator kekrig = new KekRecipientInfoGenerator();
  			kekrig.KekIdentifier = kekIdentifier;
  			kekrig.KeyEncryptionKeyOID = keyAlgorithm;
  			kekrig.KeyEncryptionKey = key;
  
  			recipientInfoGenerators.Add(kekrig);
  		}
  
  		public void AddPasswordRecipient(
  			CmsPbeKey	pbeKey,
  			string		kekAlgorithmOid)
  		{
  			Pbkdf2Params p = new Pbkdf2Params(pbeKey.Salt, pbeKey.IterationCount);
  
  			PasswordRecipientInfoGenerator prig = new PasswordRecipientInfoGenerator();
  			prig.KeyDerivationAlgorithm = new AlgorithmIdentifier(PkcsObjectIdentifiers.IdPbkdf2, p);
  			prig.KeyEncryptionKeyOID = kekAlgorithmOid;
  			prig.KeyEncryptionKey = pbeKey.GetEncoded(kekAlgorithmOid);
  
  			recipientInfoGenerators.Add(prig);
  		}
  
  		/**
  		* Add a key agreement based recipient.
  		*
  		* @param agreementAlgorithm key agreement algorithm to use.
  		* @param senderPrivateKey private key to initialise sender side of agreement with.
  		* @param senderPublicKey sender public key to include with message.
  		* @param recipientCert recipient's public key certificate.
  		* @param cekWrapAlgorithm OID for key wrapping algorithm to use.
  		* @exception SecurityUtilityException if the algorithm requested cannot be found
  		* @exception InvalidKeyException if the keys are inappropriate for the algorithm specified
  		*/
  		public void AddKeyAgreementRecipient(
  			string					agreementAlgorithm,
  			AsymmetricKeyParameter	senderPrivateKey,
  			AsymmetricKeyParameter	senderPublicKey,
  			X509Certificate			recipientCert,
  			string					cekWrapAlgorithm)
  		{
              IList recipientCerts = Platform.CreateArrayList(1);
  			recipientCerts.Add(recipientCert);
  
  			AddKeyAgreementRecipients(agreementAlgorithm, senderPrivateKey, senderPublicKey,
  				recipientCerts, cekWrapAlgorithm);
  		}
  
  		/**
  		 * Add multiple key agreement based recipients (sharing a single KeyAgreeRecipientInfo structure).
  		 *
  		 * @param agreementAlgorithm key agreement algorithm to use.
  		 * @param senderPrivateKey private key to initialise sender side of agreement with.
  		 * @param senderPublicKey sender public key to include with message.
  		 * @param recipientCerts recipients' public key certificates.
  		 * @param cekWrapAlgorithm OID for key wrapping algorithm to use.
  		 * @exception SecurityUtilityException if the algorithm requested cannot be found
  		 * @exception InvalidKeyException if the keys are inappropriate for the algorithm specified
  		 */
  		public void AddKeyAgreementRecipients(
  			string					agreementAlgorithm,
  			AsymmetricKeyParameter	senderPrivateKey,
  			AsymmetricKeyParameter	senderPublicKey,
  			ICollection				recipientCerts,
  			string					cekWrapAlgorithm)
  		{
  			if (!senderPrivateKey.IsPrivate)
  				throw new ArgumentException("Expected private key", "senderPrivateKey");
  			if (senderPublicKey.IsPrivate)
  				throw new ArgumentException("Expected public key", "senderPublicKey");
  
  			/* TODO
  			 * "a recipient X.509 version 3 certificate that contains a key usage extension MUST
  			 * assert the keyAgreement bit."
  			 */
  
  			KeyAgreeRecipientInfoGenerator karig = new KeyAgreeRecipientInfoGenerator();
  			karig.KeyAgreementOID = new DerObjectIdentifier(agreementAlgorithm);
  			karig.KeyEncryptionOID = new DerObjectIdentifier(cekWrapAlgorithm);
  			karig.RecipientCerts = recipientCerts;
  			karig.SenderKeyPair = new AsymmetricCipherKeyPair(senderPublicKey, senderPrivateKey);
  
  			recipientInfoGenerators.Add(karig);
  		}
  
          protected internal virtual AlgorithmIdentifier GetAlgorithmIdentifier(
  			string					encryptionOid,
  			KeyParameter			encKey,
  			Asn1Encodable			asn1Params,
  			out ICipherParameters	cipherParameters)
  		{
  			Asn1Object asn1Object;
  			if (asn1Params != null)
  			{
  				asn1Object = asn1Params.ToAsn1Object();
  				cipherParameters = ParameterUtilities.GetCipherParameters(
  					encryptionOid, encKey, asn1Object);
  			}
  			else
  			{
  				asn1Object = DerNull.Instance;
  				cipherParameters = encKey;
  			}
  
  			return new AlgorithmIdentifier(
  				new DerObjectIdentifier(encryptionOid),
  				asn1Object);
  		}
  
  		protected internal virtual Asn1Encodable GenerateAsn1Parameters(
  			string	encryptionOid,
  			byte[]	encKeyBytes)
  		{
  			Asn1Encodable asn1Params = null;
  
  			try
  			{
  				if (encryptionOid.Equals(RC2Cbc))
  				{
  					byte[] iv = new byte[8];
  					rand.NextBytes(iv);
  
  					// TODO Is this detailed repeat of Java version really necessary?
  
gt: 					int effKeyBits = encKeyBytes.Length * 8;