yes

.idea/.idea.ConsoleApp1/.idea/contentModel.xml

@@ -18,6 +18,8 @@
             </e>
           </e>
         </e>
+        <e p="RSA.cs" t="Include" />
+        <e p="RSAhw2.cs" t="Include" />
         <e p="Vigenere.cs" t="Include" />
       </e>
       <e p="MenuSystem" t="IncludeRecursive">

CryptoAlgo/RSA.cs

+using System;
+
+namespace CryptoAlgo
+{
+    
+    
+
+    public static class RSA
+    {
+        
+        public static string RunRSA()
+        {
+            Console.WriteLine("Welcome to RSA");
+
+            string command = "";
+
+            do
+
+            {
+                Console.WriteLine("E - Encrypt Message");
+                Console.WriteLine("D - Decrypt Message");
+                Console.WriteLine("X - Exit");
+                Console.WriteLine("-----------");
+                Console.WriteLine(">");
+                command = Console.ReadLine().ToUpper();
+                switch (command)
+                {
+                    case "E":
+                        RunRSAEncrypt();
+                        break;
+                    case "D":
+                        RunRSADecrypt();
+                        break;
+                }
+            } while (command != "X");
+
+            static void RunRSAEncrypt()
+            {
+                Console.WriteLine("Text to encrypt");
+                Console.Write(">");
+                var plainText = Console.ReadLine()?.Trim().ToUpper() ?? "";
+
+                Console.WriteLine("Enter p (Prime) value:");
+                Console.Write(">");
+                string pValue = Console.ReadLine();
+                
+                Console.WriteLine("Enter q (Prime) value:");
+                Console.Write(">");
+                string qValue = Console.ReadLine();
+
+                double q;
+                if (!double.TryParse(qValue, out q))
+             
+                {
+                    Console.WriteLine("Error: " + qValue + " is not a number");
+                }
+
+                int shiftAmount = 0;
+                double p;
+                if (!double.TryParse(pValue, out p))
+                {
+                    Console.WriteLine("Error: " + pValue + " is not a number");
+                }
+
+                else
+                {
+                    double n = p * q;
+                }
+                
+                
+                
+                
+            }
+            
+            static void RunRSADecrypt()
+            {
+                Console.WriteLine("Text to decrypt");
+                Console.Write(">");
+                var encryptedText = Console.ReadLine()?.Trim().ToUpper() ?? "";
+
+                Console.WriteLine("Amount to shift");
+                Console.Write(">");
+                string shiftAmountText = Console.ReadLine();
+
+                int shiftAmount = 0;
+                if (int.TryParse(shiftAmountText, out shiftAmount))
+                {
+                    string plainText = RSADecrypt(encryptedText, shiftAmount);
+                    Console.WriteLine("----------------");
+                    Console.WriteLine("original:" + encryptedText);
+                    Console.WriteLine("shift:" + shiftAmount);
+                    Console.WriteLine("----------------");
+                    Console.WriteLine("decrypted:" + plainText);
+                }
+                else
+                {
+                    Console.WriteLine(shiftAmountText + "is not a number");
+                }
+            }
+            return "";
+        }
+        
+        private static char[] _alphabet = new char[]
+        {
+            'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U',
+            'V', 'W', 'X', 'Y', 'Z', ' '
+        };
+        
+        static string RSAEncrypt(string plainText, int shiftAmount)
+        {
+            Console.WriteLine("Alphabet size: " + _alphabet.Length);
+            string result = "";
+                
+            for (int i = 0; i < plainText.Length; i++)
+            {
+                var letter = plainText[i];
+                var indexInAlphabet = Array.IndexOf(_alphabet, letter);
+                indexInAlphabet = (indexInAlphabet + shiftAmount) % _alphabet.Length;
+                result = result + _alphabet[indexInAlphabet];
+            }
+                
+            return result;
+        }
+            
+        static string RSADecrypt(string encryptedText, int shiftAmount)
+        {
+            Console.WriteLine("Alphabet size: " + _alphabet.Length);
+            string result = "";
+                
+            for (int i = 0; i < encryptedText.Length; i++)
+            {
+                var letter = encryptedText[i];
+                var indexInAlphabet = Array.IndexOf(_alphabet, letter);
+                indexInAlphabet = (indexInAlphabet - shiftAmount) % _alphabet.Length;
+                result = result + _alphabet[indexInAlphabet];
+            }
+                
+            return result;
+        }
+            
+            
+        
+    }
+}
+
+
+/*string encryptedText = RSAEncrypt(plainText, shiftAmount);
+Console.WriteLine("----------------");
+Console.WriteLine("original:" + plainText);
+Console.WriteLine("shift:" + shiftAmount);
+Console.WriteLine("----------------");
+Console.WriteLine("encrypted:" + encryptedText);
+*/
\ No newline at end of file

CryptoAlgo/RSAhw2.cs

+using System;
+using System.Threading;
+
+namespace CryptoAlgo
+{
+    public class RSAhw2
+    {
+
+
+        //static void Main(string[] args)
+        
+        public static string runRSA()
+        {
+            Console.WriteLine("RSA");
+            
+            var g = new Random();
+            long p;
+
+            do
+            {
+                p = g.Next(512, 10000);
+            } while (!PrimeChecker(p));
+            
+            var h = new Random();
+            int q;
+            do
+            {
+                q = h.Next(512, 10000);
+            } while (!PrimeChecker(q));
+            
+            Console.WriteLine($"P value: {p}");
+            Console.WriteLine($"Q value: {q}");
+
+            long n = p * q;
+            long m = (p - 1) * (q - 1);
+            Console.WriteLine($"n = p*q: {n}");
+            Console.WriteLine($"ф(n) = (p-1)*(q-1): {m}");
+
+            long e = 1;
+            long gcd = 0;
+
+            do
+            {
+                e++;
+                gcd = Gcd(m, e);
+            } while (gcd != 1);
+            
+            
+            
+            Console.WriteLine($"Co-prime to the ф(n): {m} is e:{e} ");
+
+            int k = 0;
+            do
+            {
+                if ((1 + k * m) % e == 0) break;
+                k++;
+            } while (true);
+            Console.WriteLine($"K: {k}");
+
+            var d = (1 + k * m) / e;
+            Console.WriteLine($"d: {d}");
+            
+            Console.WriteLine($"Public key \n n: {n} e: {e}");
+            Console.WriteLine($"Private key: p*q =  {p}*{q} = {n} d:{d}");
+            
+            Console.WriteLine("Plaintext char:");
+            var plainTextString = Console.ReadLine();
+
+            if (plainTextString.Length >= 1)
+            {
+                var table = new Int64[4, plainTextString.Length];
+
+                var i = 0;
+                while (i < plainTextString.Length)
+                {
+                    var plainText = (int) plainTextString[i];
+                    table[0, i] = plainText;
+
+                    var cypher = calcMod(plainText, e, n);
+                    table[1, i] = cypher;
+
+                    table[2, i] = calcMod(cypher, d, n);
+                    i++;
+                }
+                
+                
+                Console.Write("Char code: ");
+                for (var j = 0; j < plainTextString.Length; j++)
+                {
+                    Console.Write($" {table[0,j]}");
+                }
+                
+                Console.Write("\nCypher:    ");
+                for (var j = 0; j < plainTextString.Length; j++)
+                {
+                    Console.Write($" {table[1, j]}");
+                }
+                
+                Console.Write("\nDecrypted: ");
+                for (var j = 0; j < plainTextString.Length; j++)
+                {
+                    Console.Write($" {table[2,j]}");
+                }
+                Console.WriteLine();
+            }
+            
+            CheckRSA(p*q,e);
+            
+            static void CheckRSA(long n, long e)
+            {
+                long x = 1;
+                long y = 1;
+ 
+                do
+                {
+                    x++;
+                    y = Divide(n,x);
+                } while (!PrimeChecker(x) || !PrimeChecker(y) || y==1);
+           
+                Console.WriteLine("2 Private keys are: X: {0}, Y: {1}", x,y);
+            }
+       
+            static int calculateMod(int inputBase, int inputSecret, int inputModulus)
+            {
+                var returnMod = 1;
+                for (var i = 1; i <= inputSecret; ++i)
+                {
+                    returnMod = (returnMod * inputBase) % inputModulus;
+                }
+                return returnMod;
+            }
+
+
+            return "";
+
+
+        }
+        static bool PrimeChecker(long x)
+        {
+            for (var i = 2; i * i < x; ++i)
+            {
+                if (x % i == 0)
+                {
+                    return false;
+                }
+            }
+            return true;
+        }
+        
+        
+        
+        static long Divide(long n, long x)
+        {
+            if (n % x == 0)
+                return n / x;
+            return 1;
+        }
+        
+        static long Gcd(long a, long b)
+        {
+            //Case Divide 0
+            if (a == 0)
+                return b;
+            if (b == 0)
+                return a;
+   
+            // base case
+            if (a == b)
+                return b;
+   
+            // a is greater
+            if (a > b)
+                return Gcd(a-b, b);
+            return Gcd(a, b-a);
+        }
+        
+        static long calcMod(long inputBase, long inputSecret, long inputModulus)
+        {
+            long returnMod = 1;
+            for (var i = 1; i <= inputSecret; ++i)
+            {
+                returnMod = (returnMod * inputBase) % inputModulus;
+            }
+            return returnMod;
+        }
+
+    }
+}
\ No newline at end of file

pleaseWork/Program.cs

@@ -35,7 +35,16 @@ namespace pleaseWork
                         Command = "3",
                         Title = "Diffie-Hellman Key Exchange",
                         CommandToExecute = DH.RunDH
+                    },
+                    
+                    new MenuItem()
+                    {
+                        Command = "4",
+                        Title = "RSA",
+                        CommandToExecute = RSAhw2.runRSA
                     }
+                    
+                    
 
                 }
             };