import java.util.
Scanner;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
public class AlgorithmRC6 {
static int w = 32, r = 20;
static int[] S;
static int Pw = 0xb7e15163, Qw = 0x9e3779b9;
// CODE TO CONVERT HEXADECIMAL NUMBERS IN STRING TO BYTE ARRAY
public static byte[] hexStringToByteArray(String s) {
int string_len = s.length();
byte[] data = new byte[string_len / 2];
for (int i = 0; i < string_len; i += 2) {
data[i / 2] = (byte) ((Character.digit(s.charAt(i), 16) <<
4) + Character
.digit(s.charAt(i + 1), 16));
}
return data;
}
// CODE TO CONVERT BYTE ARRAY TO HEX FORMAT
public static String byteArrayToHex(byte[] a) {
StringBuilder sb = new StringBuilder(a.length * 2);
for (byte b : a)
sb.append(String.format("%02x", b & 0xff));
return sb.toString();
}
// KEY SCHEDULING ALGORITHM
public int[] KeySchedule(byte[] key) {
int[] S = new int[2 * r + 4];
S[0] = Pw;
int c = key.length / (w/8);
int[] L = bytestoWords(key, c);
for (int i = 1; i < (2 * r + 4); i++){
S[i] = S[i - 1] + Qw;
}
int A,B,i,j;
A=B=i=j=0;
int v = 3 * Math.max(c, (2 * r + 4));
for (int s = 0; s < v; s++) {
A = S[i] = rotateLeft((S[i] + A + B), 3);
B = L[j] = rotateLeft(L[j] + A + B, A + B);
i = (i + 1) % (2 * r + 4);
j = (j + 1) % c;
return S;
}
// ENCRYPTION ALGORITHM
public byte[] encryption(byte[] keySchArray){
int temp,t,u;
int[] temp_data = new int[keySchArray.length/4];
for(int i =0;i<temp_data.length;i++)
temp_data[i] = 0;
temp_data=convertBytetoInt(keySchArray,temp_data.length);
int A,B,C,D;
A=B=C=D=0;
A = temp_data[0];
B = temp_data[1];
C = temp_data[2];
D = temp_data[3];
B = B + S[0];
D = D + S[1];
int lgw=5;
byte[] outputArr = new byte[keySchArray.length];
for(int i = 1;i<=r;i++){
t = rotateLeft(B*(2*B+1),lgw);
u = rotateLeft(D*(2*D+1),lgw);
A = rotateLeft(A^t,u)+S[2*i];
C = rotateLeft(C^u,t)+S[2*i+1];
temp = A;
A = B;
B = C;
C = D;
D = temp;
}
A = A + S[2*r+2];
C = C + S[2*r+3];
temp_data[0] = A;
temp_data[1] = B;
temp_data[2] = C;
temp_data[3] = D;
outputArr = convertIntToByte(temp_data,keySchArray.length);
return outputArr;
}
//DECRYPTION ALGORITHM
public byte[] decryption(byte[] keySchArray){
int temp,t,u;
int A,B,C,D;
A=B=C=D=0;
int[] temp_data_decryption = new int[keySchArray.length/4];
for(int i =0;i<temp_data_decryption.length;i++)
temp_data_decryption[i] = 0;
temp_data_decryption=convertBytetoInt(keySchArray,temp_data_decryption.length);
A = temp_data_decryption[0];
B = temp_data_decryption[1];
C = temp_data_decryption[2];
D = temp_data_decryption[3];
C = C - S[2*r+3];
A = A - S[2*r+2];
int lgw=5;
byte[] outputArr = new byte[keySchArray.length];
for(int i = r;i>=1;i--){
temp = D;
D = C;
C = B;
B = A;
A = temp;
u = rotateLeft(D*(2*D+1),lgw);
t = rotateLeft(B*(2*B+1),lgw);
C= rotateRight(C-S[2*i+1],t)^u;
A= rotateRight(A-S[2*i], u)^t;
}
D=D-S[1];
B=B-S[0];
temp_data_decryption[0] = A;
temp_data_decryption[1] = B;
temp_data_decryption[2] = C;
temp_data_decryption[3] = D;
outputArr =
convertIntToByte(temp_data_decryption,keySchArray.length);
return outputArr;
}
// CONVERT INT TO BYTE FORM
public static byte[] convertIntToByte(int[] integerArray,int length){
byte[] int_to_byte=new byte[length];
for(int i = 0;i<length;i++){
int_to_byte[i] = (byte)((integerArray[i/4] >>> (i%4)*8) & 0xff);
}
return int_to_byte;
}
// CONVERT BYTE TO INT FORM
private static int[] convertBytetoInt(byte[] arr,int length){
int[] byte_to_int=new int[length];
for(int j=0; j<byte_to_int.length; j++)
{
byte_to_int[j] = 0;
}
int counter = 0;
for(int i=0;i<byte_to_int.length;i++){
byte_to_int[i] = ((arr[counter++]&0xff))|
((arr[counter++]&0xff) << 8) |
((arr[counter++]&0xff) << 16) |
((arr[counter++]&0xff) << 24);
}
return byte_to_int;
// CONVERT BYTE TO WORDS
private static int[] bytestoWords(byte[] userkey,int c) {
int[] bytes_to_words = new int[c];
for (int i = 0; i < bytes_to_words.length; i++)
bytes_to_words[i] = 0;
for (int i = 0, off = 0; i < c; i++)
bytes_to_words[i] = ((userkey[off++] & 0xFF)) |
((userkey[off++] & 0xFF) << 8)
| ((userkey[off++] & 0xFF) << 16) |
((userkey[off++] & 0xFF) << 24);
return bytes_to_words;
}
// ROTATE LEFT METHOD
private static int rotateLeft(int val, int pas) {
return (val << pas) | (val >>> (32 - pas));
}
//ROTATE RIGHT METHOD
private static int rotateRight(int val, int pas) {
return (val >>> pas) | (val << (32-pas));
}
// MAIN
public static void main(String[] args) {
String tempString;
String given_text;
String text_data;
String key_value;
String []input_text_val;
int total_lines;
BufferedWriter output_to_text_file=null;
Scanner sc=new Scanner(System.in);
try {
FileReader input_file=new FileReader("input.txt");
FileWriter output_file=new FileWriter("output.txt",false);
BufferedReader bf=new BufferedReader(input_file);
String choice=bf.readLine();
if (choice.equals("Encryption")){
given_text=bf.readLine();
input_text_val=given_text.split(":");
text_data=input_text_val[1];
key_value=bf.readLine();
String []input_key_val=key_value.split(":");
tempString=input_key_val[1];
tempString=tempString.replace(" ", "");
text_data=text_data.replace(" ", "");
byte[] key=hexStringToByteArray(tempString);
byte[] W=hexStringToByteArray(text_data);
S = new AlgorithmRC6().KeySchedule(key);
byte[] encrypt=new AlgorithmRC6().encryption(W);
String encrypted_text=byteArrayToHex(encrypt);
encrypted_text = encrypted_text.replaceAll("..", "$0
");
output_to_text_file=new BufferedWriter(output_file);
output_to_text_file.write("ciphertext: "+
encrypted_text);
}
else if (choice.equals("Decryption")) {
given_text=bf.readLine();
input_text_val=given_text.split(":");
text_data=input_text_val[1];
key_value=bf.readLine();
String []input_key_val=key_value.split(":");
tempString=input_key_val[1];
tempString=tempString.replace(" ", "");
text_data=text_data.replace(" ", "");
byte[] key2=hexStringToByteArray(tempString);
byte[] X=hexStringToByteArray(text_data);
S = new AlgorithmRC6().KeySchedule(key2);
byte[] decrypt=new AlgorithmRC6().decryption(X);
String decrypted_text=byteArrayToHex(decrypt);
decrypted_text = decrypted_text.replaceAll("..", "$0
");
output_to_text_file=new BufferedWriter(output_file);
output_to_text_file.write("plaintext: "+
decrypted_text);
}
else {
System.out.println("Invalid option");
}
} catch (FileNotFoundException e) {
System.out.println("File not found exception");
e.printStackTrace();
} catch (IOException e) {
System.out.println("IO exception");
e.printStackTrace();
}
finally
{
if(output_to_text_file != null) {
try {
output_to_text_file.close();
} catch (IOException e) {
System.out.println("File cannot be closed");
e.printStackTrace();
}
}
}
}
}
