/// <summary>
/// Constructor
/// </summary>
public Vigenere()
{
this.settings = new VigenereSettings();
this.settings.LogMessage += Vigenere_LogMessage;
}
/// <summary>
/// Does the actual Vigenere processing, i.e. encryption or decryption
/// </summary>
/// <param name="mode"></param>
private void ProcessVigenere(VigenereMode mode)
{
VigenereSettings cfg = (VigenereSettings)this.settings;
StringBuilder output = new StringBuilder(String.Empty);
string alphabet = cfg.AlphabetSymbols;
int autopos = 0;
if (!cfg.CaseSensitiveAlphabet)
{
alphabet = cfg.AlphabetSymbols.ToUpper();
}
if (inputString != null)
{
int shiftPos = 0;
for (int i = 0; i < inputString.Length; i++)
{
//get plaintext char which is currently processed
char currentChar = inputString[i];
//remember if it is upper case (ohterwise lowercase is assumed)
bool uppercase = char.IsUpper(currentChar);
//get the position of the plaintext character in the alphabet
int ppos = 0;
if (cfg.CaseSensitiveAlphabet)
{
ppos = alphabet.IndexOf(currentChar);
}
else
{
ppos = alphabet.IndexOf(char.ToUpper(currentChar));
}
if (ppos >= 0)
{
//found the plaintext character in the alphabet, begin shifting
int cpos = 0;
switch (mode)
{
case VigenereMode.encrypt:
cpos = (ppos + cfg.ShiftKey[shiftPos]) % alphabet.Length;
//inkrement shiftPos to map inputString whith all keys
//if shiftPos > ShiftKey.Length, begin again at the beginning
shiftPos++;
if (shiftPos >= cfg.ShiftKey.Length)
{
shiftPos = 0;
}
break;
case VigenereMode.decrypt:
cpos = (ppos - cfg.ShiftKey[shiftPos] + alphabet.Length) % alphabet.Length;
//inkrement shiftPos to map inputString whith all keys
//if shiftPos > ShiftKey.Length, begin again at the beginning
shiftPos++;
if (shiftPos >= cfg.ShiftKey.Length)
{
shiftPos = 0;
}
break;
case VigenereMode.autoencrypt:
//key still used
if (shiftPos < cfg.ShiftKey.Length)
{
cpos = (ppos + cfg.ShiftKey[shiftPos]) % alphabet.Length;
shiftPos++;
}
else //using plaintext
{
//taking the plaintextchar from the next position
int pkey = alphabet.IndexOf(char.ToUpper(inputString[autopos]));
//check if the next plaintextchar is in the alphabet
while (pkey < 0)
{
autopos++;
pkey = alphabet.IndexOf(char.ToUpper(inputString[autopos]));
}
cpos = (ppos + pkey) % alphabet.Length;
autopos++;
}
break;
case VigenereMode.autodecrypt:
//key still used
if (shiftPos < cfg.ShiftKey.Length)
{
cpos = (ppos - cfg.ShiftKey[shiftPos] + alphabet.Length) % alphabet.Length;
shiftPos++;
}
else //using plaintext
{
outputString = output.ToString();
//taking the deciphered plaintextchar from the next position
int pkey = alphabet.IndexOf(char.ToUpper(outputString[autopos]));
//check if the next deciphered plaintextchar is in the alphabet
while (pkey < 0)
{
autopos++;
try
{
pkey = alphabet.IndexOf(char.ToUpper(outputString[autopos]));
}
catch
{
//there is an internal failure that doesn't make sense
//supposly it has something to do with the threads -.-'/
}
}
cpos = (ppos - pkey + alphabet.Length) % alphabet.Length;
autopos++;
}
break;
}
//we have the position of the ciphertext character, now we have to output it in the right case
if (cfg.CaseSensitiveAlphabet)
{
output.Append(alphabet[cpos]);
}
else
{
if (uppercase)
{
output.Append(char.ToUpper(alphabet[cpos]));
}
else
{
output.Append(char.ToLower(alphabet[cpos]));
}
}
}
else
{
//the plaintext character was not found in the alphabet, begin handling with unknown characters
switch ((VigenereSettings.UnknownSymbolHandlingMode)cfg.UnknownSymbolHandling)
{
case VigenereSettings.UnknownSymbolHandlingMode.Ignore:
output.Append(inputString[i]);
break;
case VigenereSettings.UnknownSymbolHandlingMode.Replace:
output.Append('?');
break;
}
}
//show the progress
Progress(i, inputString.Length - 1);
}
outputString = settings.AlphabetCase | settings.MemorizeCase ? output.ToString() : output.ToString().ToUpper();
OnPropertyChanged("OutputString");
}
}
