public static string decipherCText(string Text, char[] key)
{
int[] cText = new int[Text.Length];
for (int i = 0; i < Text.Length; i++)
{
cText[i] = Text[i];
}
int[] plainText = new int[cText.Length];
if (key.Length == 0)
{
throw new Exception("Empty key");
}
for (int i = 0; i <= plainText.Length / key.Length; i++)
{
for (int j = 0; j < key.Length; j++)
{
if ((key.Length * i + j) < cText.Length)
{
int xor = cText[key.Length * i + j] ^ key[j];
plainText[key.Length * i + j] = xor;
}
}
}
return(IntConversion.intsToHex(plainText));
}
public static string decipherCTextHex(string hexText, char[] key)
{
int[] cText = IntConversion.hexToInts(hexText);
int[] plainText = new int[cText.Length];
if (key.Length == 0)
{
throw new Exception("Empty key");
}
if (hexText.Length % key.Length != 0)
{
throw new Exception("Key doesn't fit");
}
for (int i = 0; i < plainText.Length / key.Length; i++)
{
for (int j = 0; j < key.Length; j++)
{
plainText[i] = cText[key.Length * i + j] ^ key[j];
}
}
return(IntConversion.intsToString(plainText));
}
public static string decipherCText(string hexText, char key)
{
int[] cText = IntConversion.hexToInts(hexText);
int[] plainText = new int[cText.Length];
for (int i = 0; i < plainText.Length; i++)
{
plainText[i] = cText[i] ^ key;
}
return(IntConversion.intsToString(plainText));
}
public static void Challenge7()
{
StreamReader sr = new StreamReader(@"C:\Users\User\Documents\Visual Studio 2015\Projects\cryptopals\cryptopals\set 1 challenge 7.txt");
string base64 = "";
string temp = "";
while ((temp = sr.ReadLine()) != null)
{
base64 = base64 + temp;
}
BitArray bits = StringConverters.Base64ToBits(base64);
string hex = StringConverters.BitsToHex(bits);
string keyS = "YELLOW SUBMARINE";
byte[] key = new byte[16];
byte[] iv = new byte[16];
for (int i = 0; i < 16; i++)
{
key[i] = Convert.ToByte(keyS[i]);
iv[i] = Convert.ToByte(0);
}
int[] cText = IntConversion.hexToInts(hex);
byte[] cTextB = new byte[cText.Length];
for (int i = 0; i < cText.Length; i++)
{
cTextB[i] = (byte)cText[i];
}
byte[] pTextB = new byte[cText.Length];
int[] pText = new int[cText.Length];
AesManaged alg = new AesManaged {
KeySize = 128, Key = key, BlockSize = 128, Mode = CipherMode.ECB, Padding = PaddingMode.Zeros, IV = iv
};
ICryptoTransform dec = alg.CreateDecryptor(alg.Key, alg.IV);
dec.TransformBlock(cTextB, 0, cText.Length, pTextB, 0);
for (int i = 0; i < cText.Length; i++)
{
pText[i] = pTextB[i];
}
Console.WriteLine(IntConversion.intsToString(pText));
}
public static string crackMV(string hex)
{
string pText = "";
int[] hexBytes = IntConversion.hexToInts(hex);
int likelyKSize = findKeySize(hexBytes);
List <int[]> transposedBlocks = transposeBlocks(hexBytes, likelyKSize);
List <int[]> decipheredBlocks = new List <int[]>();
for (int i = 0; i < transposedBlocks.Count; i++)
{
decipheredBlocks.Add(StringConverters.stringToInts(IntSingleVigenere.decipherCaesar(IntConversion.intsToHex(transposedBlocks[i])).Item3));
}
pText = IntConversion.intsToString(undoTranspose(decipheredBlocks));
//Console.WriteLine(likelyKSize + " : " + pText);
return(pText);
}
