using System;

public class Program

{

    public static void Main()

    {

        string text = "Dgv@dmin@123";

        int key = 30;

        string encText = additiveCipher(text, key);

        string decText = decryptAdditiveCipher(encText, key);

        Console.WriteLine("PT: {0} - ET: {1} - DT: {2}",text, encText, decText);

    }

    public static string additiveCipher(string text, int key)

        {

            string CipherText = null;

            //int Key = (int)key;

​

            foreach (char c in text)

            {

                int ASCII = (int)c;

                Console.WriteLine("Character : {0} - ASCII : {1} - EncryptedASCII : {2} - EncryptedChar : {3}", c, ASCII, ASCII + key, (char)(ASCII + key));

                CipherText += ((char)(ASCII + key)).ToString();

            }

            return CipherText;

        }

    public static string decryptAdditiveCipher(string text, int key)

        {

            string Decryptedtext = null;

            //int Key = (int)key;

​

            foreach (char c in text)

            {

                int ASCII = (int)c;

                Console.WriteLine("Character : {0} - ASCII : {1} - decryptedASCII : {2} - decryptedChar : {3}", c, ASCII, ASCII - key, (char)(ASCII - key));

                Decryptedtext += ((char)(ASCII - key)).ToString();

            }

            return Decryptedtext;    

        //return JsonConvert.SerializeObject(Decryptedtext, Formatting.Indented);

        }

}