HL7 Soup

string EncryptionKey = "myPassword";
string contentToEncrypt = activityInstance.Message.Text;
byte[] clearBytes = Encoding.Unicode.GetBytes(contentToEncrypt);
            using (System.Security.Cryptography.Aes encryptor = System.Security.Cryptography.Aes.Create())
            {                
                System.Security.Cryptography.Rfc2898DeriveBytes pdb = new System.Security.Cryptography.Rfc2898DeriveBytes(EncryptionKey, new byte[] { 0x51, 0x69, 0x52, 0x7e, 0x20, 0x4d, 0x65, 0x94, 0x46, 0x65, 0x74, 0x65, 0x76 });
                encryptor.Key = pdb.GetBytes(32);
                encryptor.IV = pdb.GetBytes(16);
                using (System.IO.MemoryStream ms = new System.IO.MemoryStream())
                {
                    using (System.Security.Cryptography.CryptoStream cs = new System.Security.Cryptography.CryptoStream(ms, encryptor.CreateEncryptor(), System.Security.Cryptography.CryptoStreamMode.Write))
                    {
                        cs.Write(clearBytes, 0, clearBytes.Length);
                        cs.Close();
                    }                   
                    var encrypted = Convert.ToBase64String(ms.ToArray());
                    workflowInstance.SetVariable("Encrypted Message", encrypted);
                }
            }

string EncryptionKey = "myPassword";
string encryptedText = activityInstance.Message.Text;
byte[] cipherBytes = Convert.FromBase64String(encryptedText);
            using (System.Security.Cryptography.Aes encryptor = System.Security.Cryptography.Aes.Create())
            {
                System.Security.Cryptography.Rfc2898DeriveBytes pdb = new System.Security.Cryptography.Rfc2898DeriveBytes(EncryptionKey, new byte[] { 0x51, 0x69, 0x52, 0x7e, 0x20, 0x4d, 0x65, 0x94, 0x46, 0x65, 0x74, 0x65, 0x76 });
                encryptor.Key = pdb.GetBytes(32);
                encryptor.IV = pdb.GetBytes(16);
                using (System.IO.MemoryStream ms = new System.IO.MemoryStream())
                {
                    using (System.Security.Cryptography.CryptoStream cs = new System.Security.Cryptography.CryptoStream(ms, encryptor.CreateDecryptor(), System.Security.Cryptography.CryptoStreamMode.Write))
                    {
                        cs.Write(cipherBytes, 0, cipherBytes.Length);
                        cs.Close();
                    }                   
                    var decryptedText = Encoding.Unicode.GetString(ms.ToArray());
                    workflowInstance.SetVariable("Decrypted Text", decryptedText);
                }
            }