/**
* Separates the ciphertext into containers and calculates the frequency of each byte.
*
* @param length The known length of the key which also defines the number of containers to create
* for key determination.
* @param content The ciphertext contents read as an array of bytes.
*/
public ByteFrequencyScanner(int length, byte[] content) {
keyLength = length;
// initialize each sub list
for (int i = 0; i < length; i++) {
ciphertext.add(new ArrayList<Byte>());
}
// place each byte into their respective container
for (int i = 0; i < content.length; i++) {
int key_pos = i % keyLength;
ArrayList<Byte> subList = ciphertext.get(key_pos);
subList.add(content[i]);
}
List<Byte> searchedBytes = new ArrayList<Byte>();
for (ArrayList<Byte> sublist : ciphertext) {
ByteFrequencyList count = new ByteFrequencyList();
frequencyList.add(count);
for (Byte b : sublist) {
if (!searchedBytes.contains(b)) {
searchedBytes.add(b);
int numberOfRepetitions = countRepetition(sublist, b);
count.add(new ByteFrequency(b, numberOfRepetitions));
}
}
searchedBytes.clear();
}
}
/**
* Displays the most frequent byte in each container of monoalphabetic ciphertext. Displays more
* than one byte in each container if a given monoalphabetic ciphertext was repeated an equal
* number of times.
*/
public void printFrequentBytes() {
for (ByteFrequencyList list : frequencyList) {
System.out.print("[");
for (int i = 0; i < list.getRepetitiveBytes().length; i++) {
System.out.print(String.format("%02X", list.getRepetitiveBytes()[i]));
if (i != list.getRepetitiveBytes().length - 1) System.out.print(", ");
}
System.out.println("]");
}
}
