/*this method takes in a key and the cipher text,
* and performs every possible column swap, and returns
* the one which corresponds to the highest score*/
public static char[][] FindBestCol(char[][] child, string cipher, double[,] bookDigraph)
{
Digraph digraphCipher = new Digraph();
double childScore = Result.FinalScoreMult(digraphCipher.NormalisedPairCount(Decryption.Result(cipher, child)), bookDigraph);
char[][] temp = Key.RandKey(Key.randAlphabet()); //Initialises random new key
double tempScore = 0;
for (int col_a = 0; col_a < 5; col_a++)
{
for (int col_b = 0; col_b < 5; col_b++)
{
temp = SwapSpecificCol(col_a, col_b, child); //swap columns
tempScore = Result.FinalScoreMult(digraphCipher.NormalisedPairCount(Decryption.Result(cipher, temp)), bookDigraph);
if (tempScore > childScore)
{
childScore = tempScore; //childScore is always the highest score in this method
}
else
{
temp = SwapSpecificCol(col_a, col_b, child); //Swap columns back
}
child = temp; //child always set to the best score
}
}
return child;
}
/*this method takes in a key and the cipher text,
* and performs every possible row swap, and returns
* the one which corresponds to the highest score*/
public static char[][] FindBestRow(char[][] child, string cipher, double[,] bookDigraph)
{
Digraph digraphCipher = new Digraph();
char[][] temp = Key.RandKey(Key.randAlphabet());
string decryptedText = Decryption.Result(cipher, temp); //generates decoded message to be used to create digraph
double[,] decryptedTextDigraph = digraphCipher.NormalisedPairCount(decryptedText); //creates digraph to be used to find score
double tempScore = Result.FinalScoreMult(decryptedTextDigraph, bookDigraph); //calculates the score of child to be used to analyse the quality of the temp key
decryptedText = Decryption.Result(cipher, child); //generates decoded message to be used to create digraph
decryptedTextDigraph = digraphCipher.NormalisedPairCount(decryptedText); //creates digraph to be used to find score
double childScore = Result.FinalScoreMult(decryptedTextDigraph, bookDigraph); //calculates the score of child to be used to analyse the quality of the child key
for (int row_a = 0; row_a < 5; row_a++)
{
for (int row_b = 0; row_b < 5; row_b++)
{
temp = SwapSpecificRow(row_a, row_b, child); //swap rows
decryptedText = Decryption.Result(cipher, temp); //decrypts cipher
decryptedTextDigraph = digraphCipher.NormalisedPairCount(decryptedText); //finds digraph for decrypted txt
tempScore = Result.FinalScoreMult(decryptedTextDigraph, bookDigraph); //finds the new score of the temp key
if (tempScore > childScore)
{
childScore = tempScore; //childScore is always the highest score
}
else
{
temp = SwapSpecificRow(row_a, row_b, child); //Swap rows back
}
child = temp; //child always set to the best score
}
}
return child;
}
// <operation> <key> <plaintext address> <destination address> <= for encrypt
// <operation> <plaintext address> <destination address> <= for digraph
// <operation> <book digraph address> <cipher address> <= for crack
static void Main(string[] args)
{
try //try catch to manage exceptions. If any exceptions are thrown, they are picked up in catch by exception handler 'e'.
{
if (args[0][0] == 'E' || args[0][0] == 'e') //checks if first arg begins with e. If so, runs encrypt
{
string key = args[1]; //key passed in second argument
char[][] keyArray = Key.RandKey(key); //converts key as string into array
string plain_text = File.ReadAllText(args[2]); //reads in plain text
Console.WriteLine("You typed in the following key:" + key);
string paddedText = Preprocessor.Pad(Preprocessor.Prepare(plain_text)); //prepares text for digraph analysis
string encrypted_plain_text = Encryption.Result(paddedText, keyArray); //encrypts user defined text with user defined key (keyArray)
Console.WriteLine("Your key:");
PrintKey(keyArray);
Console.WriteLine("Encrypted text: " + encrypted_plain_text);
File.WriteAllText(args[3], encrypted_plain_text); //Writes encrypted text to a user-defined directory
}
else if (args[0][0] == 'D' || args[0][0] == 'd') //checks if first arg begins with d. If so, runs digraph
{
Digraph newDigraph = new Digraph(); //creates a new digraph
string plain_text = File.ReadAllText(args[1]); //reads in plain text from user defined directory
string padded_plain_text = Preprocessor.Pad(Preprocessor.Prepare(plain_text)); //prepares plain text for digraph analysis
double[,] digraph = newDigraph.PairCount(padded_plain_text); //creates digraph for plain text
try
{
Console.WriteLine("This is your digraph: ");
Console.WriteLine(Digraph.Print(digraph));
WriteDigraph(args[2], digraph); //writes digraph to user defined directory as .dig file
Console.WriteLine("Digraph written to " + args[2]);
}
catch (Exception eDigraph) //handles writing exceptions, i.e. cannot write to directory
{
Console.WriteLine("Cannot write digraph!");
Console.WriteLine("Error:" + eDigraph.Message);
}
}
else if (args[0][0] == 'C' || args[0][0] == 'c') //checks if first arg begins with c. If so, runs crack
{
string cipher = File.ReadAllText(args[2]); //reads cipher text from user defined directory
Console.WriteLine("Length of cipher: " + cipher.Length);
double[,] bookDigraph = ReadDigraph(args[1]); //Loads digraph from second argument
Console.WriteLine("Your loaded digraph: ");
Console.WriteLine(Digraph.Print(bookDigraph)); //Prints digraph from second argumen
var parent = Key.RandKey(Key.randAlphabet()); //Initialises parent
var child = Key.RandKey(Key.randAlphabet()); //Initialises child
Digraph digraphCipher = new Digraph();
Console.WriteLine(Convert.ToChar(7)); //Sound to indicate end of loading sequence
double parentScore; //definitions
int cycle = 0;
end = false;
addressUser = true;
while (!end)
{
string decryptedText = Decryption.Result(cipher, parent); //decrypts cipher according to parent key
double[,] decryptedTextDigraph = digraphCipher.NormalisedPairCount(decryptedText); //creates digraph of decrypted cipher
parentScore = Result.FinalScoreMult(decryptedTextDigraph, bookDigraph); //creates score of user-defined cipher digraph
child = Key.RandKey(Key.randAlphabet()); //makes new random key
parent = Crack.ReturnSoln(child, cipher, bookDigraph); //IMPORTANT: Should return solution - NOT WORKING PROPERLY, but still some functionality
decryptedText = Decryption.Result(cipher, parent); //decrypts according to parent key
decryptedTextDigraph = digraphCipher.NormalisedPairCount(decryptedText); //creates digraph according to parent key
parentScore = Result.FinalScoreMult(decryptedTextDigraph, bookDigraph); //calculates score from this digraph
while (addressUser) //loop for checking if finished
{
if (parentScore > 100000000) //number should be value of parentScore which indicates a solution has been found
{
end = true; //ends crack state
}
else
{
CheckDoneCrack(cipher, parent); //asks user whether solution is correct
}
}
cycle++; //increments cycle
File.WriteAllText("crack.sol", decryptedText);
Console.WriteLine("The decrypted text has been saved as: crack.sol.");
}
}
}
catch(Exception e) //exteption handler e handles exceptions
{
Console.WriteLine("There has been an error!");
Console.WriteLine("Error:" + e.Message); //prints exception onto console
}
Console.WriteLine("Program finished");
Console.WriteLine(Convert.ToChar(7)); Console.WriteLine(Convert.ToChar(7)); //Sound to signify end of program
Console.ReadKey();
}
public static char[][] ReturnSoln(char[][] child, string cipher, double[,] bookDigraph)
{
bool end = false;
Digraph childDigraph = new Digraph();
string newDecMsg = Decryption.Result(cipher, child);
double[,] newDecMsgDigraph = childDigraph.NormalisedPairCount(newDecMsg);
int cycle_ReturnSoln = 0;
char[][] temp = Key.RandKey(Key.randAlphabet());
double childScore = Result.FinalScoreMult(newDecMsgDigraph, bookDigraph);
while (!end) /*In this while loop, I chose to call methods to perform each function, as opposed to having all the
operations being internal. This meant that the method was easiers to test, maintain and understand.*/
{
Console.WriteLine("childScore in ReturnSoln: " + childScore + "cycle_ReturnSoln" + cycle_ReturnSoln);
Console.WriteLine("temp key: ");
Program.PrintKey(temp); //Prints temp key
Console.WriteLine("child key: ");
Program.PrintKey(child); //Prints child key
temp = SwapAllPairs(child, cipher, bookDigraph); //Swaps all possible pairs
child = temp;
newDecMsg = Decryption.Result(cipher, child); //generates decoded message to be used to create digraph
newDecMsgDigraph = childDigraph.NormalisedPairCount(newDecMsg); //creates digraph to be used to find score
childScore = Result.FinalScoreMult(newDecMsgDigraph, bookDigraph); //calculates the score of child to be used to analyse the quality of the child key
temp = FindBestRow(child, cipher, bookDigraph); //swap all rows and returns best
child = temp;
temp = SwapAllPairs(child, cipher, bookDigraph); //Swaps all possible pairs
child = temp;
newDecMsg = Decryption.Result(cipher, child); //generates decoded message to be used to create digraph
newDecMsgDigraph = childDigraph.NormalisedPairCount(newDecMsg); //creates digraph to be used to find score
childScore = Result.FinalScoreMult(newDecMsgDigraph, bookDigraph); //calculates the score of child to be used to analyse the quality of the child key
temp = FindBestCol(child, cipher, bookDigraph); //swap all columns and returns best
child = temp;
temp = SwapAllPairs(child, cipher, bookDigraph); //Swaps all possible pairs
child = temp;
newDecMsg = Decryption.Result(cipher, child); //generates decoded message to be used to create digraph
newDecMsgDigraph = childDigraph.NormalisedPairCount(newDecMsg); //creates digraph to be used to find score
childScore = Result.FinalScoreMult(newDecMsgDigraph, bookDigraph); //calculates the score of child to be used to analyse the quality of the child key
cycle_ReturnSoln++;
if (childScore > 100000000) //checks to see if score is good enough to assume correct key
{
end = true;
}
if (cycle_ReturnSoln > 10)
{
temp = Key.RandKey(Key.randAlphabet()); //sets temp equal to new random key
cycle_ReturnSoln = 0;
}
}
return child;
}
//Always returns the best pair swap
public static char[][] SwapAllPairs(char[][] child, string cipher, double[,] bookDigraph)
{
Digraph digraphCipher = new Digraph();
int col_a = 1, col_b = 0, row_a = 0, row_b = 0;
char[][] temp = child;
double tempScore = Result.FinalScoreMult(digraphCipher.NormalisedPairCount(Decryption.Result(cipher, temp)), bookDigraph);
string decryptedText;
double[,] decryptedTextDigraph;
decryptedText = Decryption.Result(cipher, child); //generates decoded message to be used to create digraph
decryptedTextDigraph = digraphCipher.NormalisedPairCount(decryptedText); //creates digraph to be used to find score
double childScore = Result.FinalScoreMult(decryptedTextDigraph, bookDigraph); //calculates the score of child to be used to analyse the quality of the child key
/*the for loop below swaps every possible combination of letter swaps and keeps the combination which gives the best score*/
for (col_a = 0; col_a < 5; col_a++)
{
for (row_a = 0; row_a < 5; row_a++)
{
for (col_b = 0; col_b < 5; col_b++)
{
for (row_b = 0; row_b < 5; row_b++)
{
temp = SwapPair(row_a, col_a, row_b, col_b, child); //makes swap on specific paire
decryptedText = Decryption.Result(cipher, temp); //decrypts cipher
decryptedTextDigraph = digraphCipher.NormalisedPairCount(decryptedText); //finds digraph for decrypted txt
tempScore = Result.FinalScoreMult(decryptedTextDigraph, bookDigraph); //finds the new score of the temp key
if ((tempScore > childScore))
{
childScore = tempScore; //childScore is always the highest score
}
else
{
temp = SwapPair(row_a, col_a, row_b, col_b, child); //Swap back
}
child = temp; //Child always set to the best score
}
}
}
}
return child;
}
