Write (char)147 to output file become (char)63 when read.

Question

Hi,
I was doing an encryption for my assignment. And here I found a problem.
               FileWriter fstream = new FileWriter("output.out");
               BufferedWriter dos = new BufferedWriter(fstream);
dos.write((char)147);
dos.close(); fstream.close();
When I tried to read the output.out file using this function:
               File inputFile = new File(filename);
               FileInputStream fis = new FileInputStream(inputFile);
               BufferedInputStream bis = new BufferedInputStream(fis);
               BufferedReader dis = new BufferedReader(new InputStreamReader(bis));
char test = dis.read();
dis.close(); bis.close(); fis.close();
It shows that the test character is representing (char)63 (question mark). Any idea on how to solve this? I want to write (char)147 to the file and read it as (char)147, not as (char)63.
Thanks in advance,
Dennis A.

Answer 1

dennis_lin007 wrote:
Ok thanks a lot!!
I'm using RSA encryption, and if the mod is > 255, there are probabilities that its result may contain a value greater than 255. The implication of this is that you are encrypting byte-by-byte which does not make sense. Assuming that you are writing the RSA code from scratch and not using the JCE then consider using BigInteger. BigInteger has all the ancillary methods you will need to implement RSA.