public string Decrypt(IEncryptionParameters encParams)
{
Console.WriteLine("Enter file location and name of text file containing encrypted text:");
string cipherTextFileName = encParams.GetEncryptedFileName(); //to take in and store input for file name
string cipherText = System.IO.File.ReadAllText(cipherTextFileName);
//Load the text contents to be decrypted
Console.WriteLine();
Console.WriteLine("Enter key for decryption:");
string key = encParams.GetEncryptionKey();
int offsetFactor = CalculateOffsetFactor(key);
//enter the key as 8 character string via user input and then calculate the offset value using it
string text = "";
int charNum = 0; //to store the ascii values of each character
char charVal = ' '; //to store each of the characters themselves constituting the actual string of deciphered text
//initialize values
for (int i = 0; i < cipherText.Length; i++) //looping through each character in the text to be encrypted
{
charNum = (int)cipherText[i];
//store the ASCII value of the current character
if (charNum != 32) //check if it is a space character, which is to be ignored while encrypting
{
charNum -= offsetFactor;
//minus offset factor
if (charNum < 33)
{
charNum += 94;
} //making sure the ASCII code does not go out of the given bounds for english characters
}
charVal = (char)charNum;
//convert the offset ASCII value to a character
text += charVal;
//append this character to a string containing the encrypted text
}
return(text);
}
public void Encrypt(IEncryptionParameters encParams)
{
Console.WriteLine("Enter file location and name for text to be encrypted:");
string fileName = encParams.GetDecryptedFileName(); //to take in and store input for file name
string text = System.IO.File.ReadAllText(fileName);
//load the text contents to be encrypted
string key = GenerateKey();
//generate an 8 character key
Console.WriteLine();
Console.WriteLine("Key:");
Console.WriteLine();
Console.WriteLine(key);
int offsetFactor = CalculateOffsetFactor(key);
//use the key generated earlier to get an offset factor
string cipherText = "";
int charNum = 0; //to store the ascii values of each character
char charVal = ' '; //to store each of the characters themselves constituting the actual string of ciphered text
//initialize values to be used
for (int i = 0; i < text.Length; i++) //looping through each character in the text to be encrypted
{
charNum = (int)text[i];
//store the ASCII value of the current character
if (charNum != 32) //check if it is a space character, which is to be ignored while encrypting
{
charNum += offsetFactor;
//add offset factor
if (charNum > 126)
{
charNum -= 94;
} //making sure the ASCII code does not go out of the given bounds for english characters
}
charVal = (char)charNum;
//convert the offset ASCII value to a character
cipherText += charVal;
//append this character to a string containing the encypted text
}
Console.WriteLine();
Console.WriteLine("Enter a file name and location for a new text file to store encrypted text:");
string newFileName = encParams.GetEncryptedFileName();
System.IO.File.WriteAllText(newFileName, cipherText);
//write the encrypted text to the given file location
Console.WriteLine();
Console.WriteLine("File encrypted and stored.");
}
