unpack-2021-02-06.java

import java.io.*;
public class decrypt {
    public static void main(String[] args) {
        System.out.println("hello, world!");
        InputStream input = null;

        try {
            input = new FileInputStream("1k7vcor");
        } catch (FileNotFoundException e) {
        }

        byte[] flag_str = new byte[0xb];

        try {
            input.read(flag_str);
        } catch (IOException e) {
        }

        int flag = (int)flag_str[8] & 0xff | ((int)flag_str[9] & 0xff) << 8 | ((int)flag_str[10] & 0xff) << 0x10;

        byte[] content_tmp = new byte[1];

        try {
            input.read(content_tmp);
        } catch (IOException e) {
        }

        decrypt(flag, content_tmp[0], input);
    }

    static void decrypt(int flags, byte content, InputStream input) {
        OutputStream output = null;

        int iVar1;
        InputStream pIVar2;
        Object ref_00;
        ByteArrayOutputStream local_0;
        byte[] pbVar3;
        int iVar4;
        Object[] ppOVar5;

        local_0 = new ByteArrayOutputStream();
        pbVar3 = new byte[0x1000];
        while( true ) {
            iVar1 = Math.min(flags,0x1000);
            
            try {
                iVar1 = input.read(pbVar3,0,iVar1);
            } catch (IOException e) {

            }
            
            if ((iVar1 == -1) || (iVar1 == 0)) break;
            flags = flags - iVar1;
            iVar4 = 0;
            while (iVar4 < iVar1) {
                pbVar3[iVar4] = (byte)(pbVar3[iVar4] ^ content);
                iVar4 = iVar4 + 1;
            }
            local_0.write(pbVar3,0,iVar1);
        }

        try {
            output = new FileOutputStream("decrypted");
            local_0.writeTo(output);
        } catch (FileNotFoundException e) {
        } catch (IOException e2) {      
        }
    }
}