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PayloadFileProcess.java
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PayloadFileProcess.java
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import java.util.*;
import java.io.*;
public class PayloadFileProcess {
private List<Byte> allBytes;
private int[] bitForm;
private Block[] blocks;
/* constructor to process payload file */
public PayloadFileProcess(String fileName) throws IOException, FileNotFoundException {
allBytes = new ArrayList<Byte>();
System.out.println("file is hidden");
byte[] temp = buildByteFile(fileName);
for(byte chunk:temp)
allBytes.add(chunk);//each chunk is one byte data
bitify();// convert each char into 8 bits
blockify();// group bytes into blocks
}
/* create payload bytes flow */
public byte[] buildByteFile(String fileName) throws IOException, FileNotFoundException {
File payload = new File("Payloads/" + fileName);
int fileLength = (int) payload.length();
System.out.println("File size: " + (fileLength / 1024) + " KB");
System.out.println("File name: " + fileName);
FileInputStream fis = new FileInputStream(payload);
byte[] byteFile = new byte[fileLength + fileName.length() + 5];
int contentStart = modifyHeader(fileLength, fileName, byteFile);
fis.read(byteFile, contentStart, (int) payload.length());
return byteFile;
}
/* add header bits into bitflow */
public int modifyHeader(int fileLength, String fileName, byte[] byteForm){
for (int k = 0; k < 4; k++){
byteForm[k] = (byte) (((fileLength >> (24 - k*8)) & 0xFF)-128);// read the length of fileload
}
byteForm[4] = (byte) (fileName.length()-128);
int j = 0;
for(int i = 5; i < 5 + fileName.length(); i++){
byteForm[i] = (byte)(fileName.charAt(j++)-128);
//System.out.println(byteForm[i]);//print filename
}
return fileName.length() + 5;// return start position
}
/* convert bytes flow into bits flow */
public void bitify(){
int q = 0;
bitForm = new int[allBytes.size() * 8];
for(byte val : allBytes)
for(int k = 0; k < 8;k++)
bitForm[q++] = ((val + 128)>> (7 - k)) % 2;
}
/* divide bits flow into separate blocks, each block has 64 bits */
public void blockify(){
int p = 0;
blocks = new Block[(int) Math.ceil(bitForm.length / 63.0)];
for (int j = 0; j < bitForm.length; j+=63) {
int[] feed = new int[64];
for (int k = 1; (j + k - 1) < bitForm.length && k < 64; k++)
feed[k] = bitForm[j + k - 1];
blocks[p] = new Block(feed);
p++;
}
}
/* return blocks' length */
public int blockLength() {
return blocks.length;
}
/* get number of conjugated blocks */
public int getNumOfConjugated() {
int count = 0;
for(Block block:blocks)
if(block.isConjugated())
count++;
return count;
}
/* get block by index */
public Block getBlock(int i) {
return blocks[i];
}
}