public static void Rc4AndCngWrappersDontMixTest()
        {
            //
            // Combination of RC4 over a CAPI certificate.
            //
            //  This works as long as the PKCS implementation opens the cert using CAPI. If he creates a CNG wrapper handle (by passing CRYPT_ACQUIRE_PREFER_NCRYPT_KEY_FLAG),
            //  the test fails with a NOTSUPPORTED crypto exception inside Decrypt(). The same happens if the key is genuinely CNG.
            //

            byte[] content = { 6, 3, 128, 33, 44 };
            AlgorithmIdentifier rc4 = new AlgorithmIdentifier(new Oid(Oids.Rc4));

            EnvelopedCms ecms = new EnvelopedCms(new ContentInfo(content), rc4);
            CmsRecipientCollection recipients = new CmsRecipientCollection(new CmsRecipient(Certificates.RSAKeyTransferCapi1.GetCertificate()));
            ecms.Encrypt(recipients);
            byte[] encodedMessage = ecms.Encode();

            ecms = new EnvelopedCms();
            ecms.Decode(encodedMessage);

            using (X509Certificate2 cert = Certificates.RSAKeyTransferCapi1.TryGetCertificateWithPrivateKey())
            {
                if (cert == null)
                    return; // Sorry - CertLoader is not configured to load certs with private keys - we've tested as much as we can.

                X509Certificate2Collection extraStore = new X509Certificate2Collection();
                extraStore.Add(cert);
                ecms.Decrypt(extraStore);
            }

            ContentInfo contentInfo = ecms.ContentInfo;
            Assert.Equal<byte>(content, contentInfo.Content);
        }

 private static void VerifyCertificates0(byte[] encodedMessage)
 {
     EnvelopedCms ecms = new EnvelopedCms();
     ecms.Decode(encodedMessage);
     X509Certificate2Collection certs = ecms.Certificates;
     Assert.Equal(0, certs.Count);
 }

 private static void VerifyVersion0(byte[] encodedMessage)
 {
     EnvelopedCms ecms = new EnvelopedCms();
     ecms.Decode(encodedMessage);
     int version = ecms.Version;
     Assert.Equal(0, version);
 }

 private static void VerifyUnprotectedAttributes0(byte[] encodedMessage)
 {
     EnvelopedCms ecms = new EnvelopedCms();
     ecms.Decode(encodedMessage);
     AsnEncodedData[] attributes = ecms.UnprotectedAttributes.FlattenAndSort();
     Assert.Equal(0, attributes.Length);
 }

        public static void ImportEdgeCase()
        {
            //
            // Pfx's imported into a certificate collection propagate their "delete on Dispose" behavior to its cloned instances:
            // a subtle difference from Pfx's created using the X509Certificate2 constructor that can lead to premature or
            // double key deletion. Since EnvelopeCms.Decrypt() has no legitimate reason to clone the extraStore certs, this shouldn't
            // be a problem, but this test will verify that it isn't.
            //

            byte[] encodedMessage =
                ("3082010c06092a864886f70d010703a081fe3081fb0201003181c83081c5020100302e301a311830160603550403130f5253"
                + "414b65795472616e7366657231021031d935fb63e8cfab48a0bf7b397b67c0300d06092a864886f70d01010105000481805e"
                + "bb2d08773594be9ec5d30c0707cf339f2b982a4f0797b74d520a0c973d668a9a6ad9d28066ef36e5b5620fef67f4d79ee50c"
                + "25eb999f0c656548347d5676ac4b779f8fce2b87e6388fbe483bb0fcf78ab1f1ff29169600401fded7b2803a0bf96cc160c4"
                + "96726216e986869eed578bda652855c85604a056201538ee56b6c4302b06092a864886f70d010701301406082a864886f70d"
                + "030704083adadf63cd297a86800835edc437e31d0b70").HexToByteArray();

            EnvelopedCms ecms = new EnvelopedCms();
            ecms.Decode(encodedMessage);

            using (X509Certificate2 cert = Certificates.RSAKeyTransfer1.LoadPfxUsingCollectionImport())
            {
                X509Certificate2Collection extraStore = new X509Certificate2Collection(cert);
                ecms.Decrypt(extraStore);

                byte[] expectedContent = { 1, 2, 3 };
                ContentInfo contentInfo = ecms.ContentInfo;
                Assert.Equal<byte>(expectedContent, contentInfo.Content);
            }
        }

 private static void VerifyUnprotectedAttributes1_DocumentDescription(byte[] encodedMessage)
 {
     EnvelopedCms ecms = new EnvelopedCms();
     ecms.Decode(encodedMessage);
     AsnEncodedData[] attributes = ecms.UnprotectedAttributes.FlattenAndSort();
     Assert.Equal(1, attributes.Length);
     attributes[0].AssertIsDocumentationDescription("My Description");
 }

 private byte[] EncryptedBytes(byte[] bytes)
 {
     var contentInfo = new ContentInfo(bytes);
     var encryptAlgoOid = new Oid("2.16.840.1.101.3.4.1.42"); // AES-256-CBC            
     var envelopedCms = new EnvelopedCms(contentInfo, new AlgorithmIdentifier(encryptAlgoOid));
     var recipient = new CmsRecipient(CryptographicCertificate);
     envelopedCms.Encrypt(recipient);
     return envelopedCms.Encode();
 }

 private static void VerifyAlgorithmRc2_128(byte[] encodedMessage)
 {
     EnvelopedCms ecms = new EnvelopedCms();
     ecms.Decode(encodedMessage);
     AlgorithmIdentifier algorithm = ecms.ContentEncryptionAlgorithm;
     Assert.NotNull(algorithm.Oid);
     Assert.Equal(Oids.Rc2, algorithm.Oid.Value);
     Assert.Equal(128, algorithm.KeyLength);
 }

        /// <summary>
        /// Encrypts the specified string.
        /// </summary>
        /// <param name="plaintext">The plaintext to be encrypted.</param>
        /// <param name="certificate">The certificate to be used for encryption.</param>
        /// <returns>The encrypted text.</returns>
        public static string Encrypt(this string plaintext, X509Certificate2 certificate)
        {
            var contentInfo = new ContentInfo(Encoding.UTF8.GetBytes(plaintext));
            var envelopedCms = new EnvelopedCms(contentInfo);

            var cmsRecipient = new CmsRecipient(certificate);
            envelopedCms.Encrypt(cmsRecipient);

            return Convert.ToBase64String(envelopedCms.Encode());
        }

 public static string DecryptEnvelop(string base64EncryptedString)
 {
     var encryptedBytes = Convert.FromBase64String(base64EncryptedString);
     var envelope = new EnvelopedCms();
     envelope.Decode(encryptedBytes);
     var store = new X509Store(StoreName.My, StoreLocation.LocalMachine);
     store.Open(OpenFlags.ReadOnly);
     envelope.Decrypt(store.Certificates);
     return Encoding.UTF8.GetString(envelope.ContentInfo.Content);
 }

        public static void DecodeCertificates0_RoundTrip()
        {
            ContentInfo contentInfo = new ContentInfo(new byte[] { 1, 2, 3 });
            EnvelopedCms ecms = new EnvelopedCms(contentInfo);
            using (X509Certificate2 cert = Certificates.RSAKeyTransfer1.GetCertificate())
            {
                CmsRecipient cmsRecipient = new CmsRecipient(cert);
                ecms.Encrypt(cmsRecipient);
            }
            byte[] encodedMessage = ecms.Encode();

            VerifyCertificates0(encodedMessage);
        }

 public static void DecodeAlgorithmDes_RoundTrip()
 {
     AlgorithmIdentifier algorithm = new AlgorithmIdentifier(new Oid(Oids.Des));
     ContentInfo contentInfo = new ContentInfo(new byte[] { 1, 2, 3 });
     EnvelopedCms ecms = new EnvelopedCms(contentInfo, algorithm);
     using (X509Certificate2 cert = Certificates.RSAKeyTransfer1.GetCertificate())
     {
         CmsRecipient cmsRecipient = new CmsRecipient(cert);
         ecms.Encrypt(cmsRecipient);
     }
     byte[] encodedMessage = ecms.Encode();
     VerifyAlgorithmDes(encodedMessage);
 }

        public static void DecodeRecipients3_RoundTrip()
        {
            ContentInfo contentInfo = new ContentInfo(new byte[] { 1, 2, 3 });
            EnvelopedCms ecms = new EnvelopedCms(contentInfo);
            CmsRecipientCollection recipients = new CmsRecipientCollection();
            foreach (X509Certificate2 cert in s_certs)
            {
                recipients.Add(new CmsRecipient(cert));
            }
            ecms.Encrypt(recipients);
            byte[] encodedMessage = ecms.Encode();

            VerifyRecipients3(encodedMessage);
        }

		private void DefaultProperties (EnvelopedCms ep, int contentLength, int version) 
		{
			Assert.AreEqual (0, ep.Certificates.Count, "Certificates");
			Assert.AreEqual (0, ep.ContentEncryptionAlgorithm.KeyLength, "ContentEncryptionAlgorithm.KeyLength");
			Assert.AreEqual (tdesName, ep.ContentEncryptionAlgorithm.Oid.FriendlyName, "ContentEncryptionAlgorithm.Oid.FriendlyName");
			Assert.AreEqual (tdesOid, ep.ContentEncryptionAlgorithm.Oid.Value, "ContentEncryptionAlgorithm.Oid.Value");
			Assert.AreEqual (0, ep.ContentEncryptionAlgorithm.Parameters.Length, "ContentEncryptionAlgorithm.Parameters");
			Assert.AreEqual (p7DataName, ep.ContentInfo.ContentType.FriendlyName, "ContentInfo.ContentType.FriendlyName");
			Assert.AreEqual (p7DataOid, ep.ContentInfo.ContentType.Value, "ContentInfo.ContentType.Value");
			Assert.AreEqual (contentLength, ep.ContentInfo.Content.Length, "ContentInfo.Content");
			Assert.AreEqual (0, ep.RecipientInfos.Count, "RecipientInfos");
			Assert.AreEqual (0, ep.UnprotectedAttributes.Count, "UnprotectedAttributes");
			Assert.AreEqual (version, ep.Version, "Version");
		}

        public static string Decrypt(string encryptedString)
        {
            // パスワードを復号
            var store = new X509Store(StoreLocation.LocalMachine); // (StoreLocation.LocalMachine);
            store.Open(OpenFlags.ReadOnly);

            var encPasswordBase64 = Convert.FromBase64String(encryptedString);

            var enveloped = new EnvelopedCms();
            enveloped.Decode(encPasswordBase64);
            enveloped.Decrypt(store.Certificates);

            return Encoding.UTF8.GetString(enveloped.ContentInfo.Content);
        }

        /// <summary>
        /// Decrypts enveloped mime content.
        /// </summary>
        /// <param name="cert">Decrypting certificate.</param>
        /// <returns>Returns decrypted enveloped mime content.</returns>
        /// <exception cref="ArgumentNullException">Is raised when <b>cert</b> is null reference.</exception>
        /// <exception cref="InvalidOperationException">Is raised when <b>smime-type != enveloped-data</b>.</exception>
        public MIME_Message GetEnvelopedMime(X509Certificate2 cert)
        {
            if(cert == null){
                throw new ArgumentNullException("cert");
            }
            if(!string.Equals(this.Entity.ContentType.Parameters["smime-type"],"enveloped-data",StringComparison.InvariantCultureIgnoreCase)){
                throw new InvalidOperationException("The VerifySignature method is only valid if Content-Type parameter smime-type=enveloped-data.");
            }

            EnvelopedCms envelopedCms = new EnvelopedCms();
            envelopedCms.Decode(this.Data);

            X509Certificate2Collection certificates = new X509Certificate2Collection(cert);
            envelopedCms.Decrypt(certificates);

            return MIME_Message.ParseFromStream(new MemoryStream(envelopedCms.Encode()));
        }

        /// <summary>
        /// Decrypts the specified string.
        /// </summary>
        /// <param name="ciphertext">The ciphertext to be decrypted.</param>
        /// <param name="certificates">A set of certificates containing the one that was used to encrypt the ciphertext.</param>
        /// <returns>The decrypted text.</returns>
        public static string Decrypt(this string ciphertext, params X509Certificate2[] certificates)
        {
            var store = new X509Store(StoreName.My, StoreLocation.LocalMachine);

            store.Open(OpenFlags.ReadOnly);
            
            var certCollection = store.Certificates;

            if (certificates != null && certificates.Length > 0)
            {
                certCollection.AddRange(certificates);
            }

            var envelopedCms = new EnvelopedCms();
            envelopedCms.Decode(Convert.FromBase64String(ciphertext));
            envelopedCms.Decrypt(certCollection);
            return Encoding.UTF8.GetString(envelopedCms.ContentInfo.Content);
        }

 public static void ZeroLengthContent_RoundTrip()
 {
     ContentInfo contentInfo = new ContentInfo(Array.Empty<byte>());
     EnvelopedCms ecms = new EnvelopedCms(contentInfo);
     using (X509Certificate2 cert = Certificates.RSAKeyTransfer1.GetCertificate())
     {
         CmsRecipient cmsRecipient = new CmsRecipient(cert);
         try
         {
             ecms.Encrypt(cmsRecipient);
         }
         catch (CryptographicException e)
         {
             throw new Exception("ecms.Encrypt() threw " + e.Message + ".\nIf you're running on the desktop CLR, this is actually an expected result.");
         }
     }
     byte[] encodedMessage = ecms.Encode();
     ValidateZeroLengthContent(encodedMessage);
 }

        public static void ImportEdgeCaseSki()
        {
            byte[] encodedMessage =
                ("3081f206092a864886f70d010703a081e43081e10201023181ae3081ab0201028014f2008aa9fa3742e8370cb1674ce1d158"
                + "2921dcc3300d06092a864886f70d01010105000481804336e978bc72ba2f5264cd854867fac438f36f2b3df6004528f2df83"
                + "4fb2113d6f7c07667e7296b029756222d6ced396a8fffed32be838eec7f2e54b9467fa80f85d097f7d1f0fbde57e07ab3d46"
                + "a60b31f37ef9844dcab2a8eef4fec5579fac5ec1e7ee82409898e17d30c3ac1a407fca15d23c9df2904a707294d78d4300ba"
                + "302b06092a864886f70d010701301406082a864886f70d03070408355c596e3e8540608008f1f811e862e51bbd").HexToByteArray();

            EnvelopedCms ecms = new EnvelopedCms();
            ecms.Decode(encodedMessage);

            using (X509Certificate2 cert = Certificates.RSAKeyTransfer1.LoadPfxUsingCollectionImport())
            {
                X509Certificate2Collection extraStore = new X509Certificate2Collection(cert);
                ecms.Decrypt(extraStore);

                byte[] expectedContent = { 1, 2, 3 };
                ContentInfo contentInfo = ecms.ContentInfo;
                Assert.Equal<byte>(new byte[] { 1, 2, 3 }, contentInfo.Content);
                Assert.Equal<byte>(expectedContent, contentInfo.Content);
            }
        }

        /// <summary>
        /// Encrypts the message and envelopes it for multiple recipients.
        /// </summary>
        /// <param name="recipients">An object containing the recipients' certificates with public keys.</param>
        /// <example>
        /// <code>
        /// [C#]
        /// 
        /// CmsRecipientCollection recipients = new CmsRecipientCollection();
        /// 
        /// recipients.Add(new CmsRecipient(new X509Certificate2("C:\\recipient1.cer")));
        /// recipients.Add(new CmsRecipient(new X509Certificate2("C:\\recipient2.cer")));
        /// 
        /// message.SmimeEnvelopeAndEncryptFor(recipients);
        /// </code>
        /// </example>
        public void SmimeEnvelopeAndEncryptFor(CmsRecipientCollection recipients)
        {
            string mimeString = this.ToMimeString();
            byte[] toencrypt = Encoding.ASCII.GetBytes(mimeString);
            EnvelopedCms cms = new EnvelopedCms(new ContentInfo(toencrypt));
            cms.Encrypt(recipients);

            MimePart envelope = new MimePart();

            envelope.ContentType.MimeType = "application/pkcs7-mime";
            envelope.ContentType.Parameters.Add("smime-type", "encrypted-data");
            envelope.ContentType.Parameters.Add("name", "smime.p7m");
            envelope.ContentDisposition.Disposition = "attachment";
            envelope.ContentDisposition.FileName = "smime.p7m";
            envelope.ContentTransferEncoding = ContentTransferEncoding.Base64;

            envelope.BinaryContent = cms.Encode();

            this.PartTreeRoot = envelope;

            this.ContentType = this.PartTreeRoot.ContentType;
            this.ContentDisposition = this.PartTreeRoot.ContentDisposition;
            this.ContentTransferEncoding = this.PartTreeRoot.ContentTransferEncoding;
        }