FileProcessClient/utils/CommonUtils.cs

using FileProcessClient.domain;
using System.Runtime.InteropServices;
using System.Security.Cryptography;
using System.Text;
using System.Xml.Linq;

namespace edu.huvtc.utils
{
    internal class CommonUtils
    {
        [DllImport("kernel32")]
        private static extern long WritePrivateProfileString(string name, string key, string val,
                                                       string filePath);
        [DllImport("kernel32")]
        private static extern int GetPrivateProfileString(string section, string key, string def,
                                                          StringBuilder retVal, int size,
                                                          string filePath);

        private const int AesBlockByteSize = 128 / 8;

        private const int PasswordSaltByteSize = 128 / 8;

        private const int PasswordByteSize = 256 / 8;

        private const int PasswordIterationCount = 100_000;

        private static readonly Encoding StringEncoding = Encoding.UTF8;

        private static readonly RandomNumberGenerator Random = RandomNumberGenerator.Create();

        private static String password = "from huvtc passwords 123412;,[p;[; 172634812";

        private static string INIPath = Convert.ToString(System.AppDomain.CurrentDomain.BaseDirectory) + "Config.ini";

        private static string Token = "";

        private static string serverUrl = "";

        private static User user;

        public static User getUser()
        {
            return user;
        }

        public static void setUser(User data)
        {
            user = data;
        }


        public static void setToken(string token)
        {
            writeToIni("security", "token", token);
            Token = token;
        }

        public static string getToken()
        {
            if (Token == null || Token == "")
            {
                Token = readFromFile("security", "token");
            }
            return Token;
        }

        public static void writeToIni(string name, string key, string value)
        {
            WritePrivateProfileString(name, key, value, INIPath);
        }

        public static string readFromFile(string name, string key)
        {
            StringBuilder builder = new StringBuilder(255);
            int ini = GetPrivateProfileString(name, key, "", builder, 255, INIPath);            
            return builder.ToString();
        }


        public static byte[] EncryptString(string toEncrypt)
        {
            using (var aes = Aes.Create())
            {
                var keySalt = GenerateRandomBytes(PasswordSaltByteSize);
                var key = GetKey(keySalt);
                var iv = GenerateRandomBytes(AesBlockByteSize);

                using (var encryptor = aes.CreateEncryptor(key, iv))
                {
                    var plainText = StringEncoding.GetBytes(toEncrypt);
                    var cipherText = encryptor
                        .TransformFinalBlock(plainText, 0, plainText.Length);

                    var result = MergeArrays(keySalt, iv, cipherText);
                    return result;
                }
            }
        }


        public static string DecryptToString(byte[] encryptedData)
        {
            using (var aes = Aes.Create())
            {
                var keySalt = encryptedData.Take(PasswordSaltByteSize).ToArray();
                var key = GetKey(keySalt);
                var iv = encryptedData
                    .Skip(PasswordSaltByteSize).Take(AesBlockByteSize).ToArray();
                var cipherText = encryptedData
                    .Skip(PasswordSaltByteSize + AesBlockByteSize).ToArray();

                using (var encryptor = aes.CreateDecryptor(key, iv))
                {
                    var decryptedBytes = encryptor
                        .TransformFinalBlock(cipherText, 0, cipherText.Length);
                    return StringEncoding.GetString(decryptedBytes);
                }
            }
        }

        private static byte[] GetKey(byte[] passwordSalt)
        {
            var keyBytes = StringEncoding.GetBytes(password);

            using (var derivator = new Rfc2898DeriveBytes(
                keyBytes, passwordSalt,
                PasswordIterationCount, HashAlgorithmName.SHA256))
            {
                return derivator.GetBytes(PasswordByteSize);
            }
        }

        private static byte[] GenerateRandomBytes(int numberOfBytes)
        {
            var randomBytes = new byte[numberOfBytes];
            Random.GetBytes(randomBytes);
            return randomBytes;
        }

        private static byte[] MergeArrays(params byte[][] arrays)
        {
            var merged = new byte[arrays.Sum(a => a.Length)];
            var mergeIndex = 0;
            for (int i = 0; i < arrays.GetLength(0); i++)
            {
                arrays[i].CopyTo(merged, mergeIndex);
                mergeIndex += arrays[i].Length;
            }

            return merged;
        }

        public static string getServerUrl()
        {
            if (serverUrl == null || serverUrl.Length == 0)
            {
                serverUrl = readFromFile("common", "server_url");
            }
            return serverUrl;
        }

        public static string getTokenFormIni()
        {
            return readFromFile("security", "token");
        }

        public static void savePassword(string username, string password)
        {
            username = Convert.ToBase64String(CommonUtils.EncryptString(username));

            password = Convert.ToBase64String(CommonUtils.EncryptString(password));

            writeToIni("userData", "userName", username);

            writeToIni("userData", "password", password);
        }

        public static string getApiUrl(string name)
        {
            return readFromFile("ApiUrls", name);
            
        }

        public static string getFtpServer()
        {
            return readFromFile("ftp_server", "server_ip");
        }

        public static string getFtpUsr()
        {
            return getDecryptValue("ftp_server", "ftp_user");            
        }

        public static string getFtpPassword()
        {
            return getDecryptValue("ftp_server", "ftp_password");
           
        }

        private static string getDecryptValue(string name, string item)
        {
            string str = readFromFile(name, item);
            if (str == null)
            {
                return "";
            }
            else
            {
                return DecryptToString(Convert.FromBase64String(str));
            }
        }

        public static int getFtpServerPort()
        {
            return int.Parse(readFromFile("ftp_server", "server_port"));
        }
    }
}