使用RSA和Java加密声音文件

Question

所以，我正在尝试使用Java的RSA库加密和解密声音文件。当我使用字符串进行操作时它没有问题，我研究了RSA加密，所以我知道我在做什么。问题必须是处理文件或BigIntegers。

加密文件中的字节，然后解密并将其放入新文件的代码：

            File sound = new File("F://java/Projekt kryptering/ljudtest.wma");
            FileReader fr = new FileReader(sound);
            int fragSize = 200;
            ArrayList<BigInteger> encryptedFragments = new ArrayList<BigInteger>((int)(sound.length()/fragSize)); //create an aproximation on number of BigIntegers required
            byte byt;
            byte[] buf = new byte[fragSize];
            int bufPos = 0;
            while((byt = (byte)fr.read()) != -1){
                buf[bufPos++] = byt;
                if(bufPos == fragSize){
                    BigInteger soundFrag = new BigInteger(buf);
                    System.out.println("unencrypted bigInt: " + soundFrag);
                    encryptedFragments.add(soundFrag.modPow(pub.getPublicExponent(), pub.getModulus()));
                    bufPos = 0;
                }
            }
            fr.close();

            File decryptedSound = new File("F://java/Projekt kryptering/ljudtest2.wma");
            decryptedSound.createNewFile();
            FileWriter fw = new FileWriter(decryptedSound);
            for(BigInteger frag : encryptedFragments){
                BigInteger decrypted = frag.modPow(priv.getPrivateExponent(), priv.getModulus());
                System.out.println("decrypted frag " + decrypted);
                byte[] frags = decrypted.toByteArray();
                for(byte fragg : frags)
                    fw.write(fragg);
            }
            fw.close();

当我尝试这样做时会发生的结果是生成的文件只有276个字节（原始文件是22,3kB）。您还可以在代码中看到一些Sytem.outs，这里的结果来自：

unencrypted bigInt: <Very long number>
unencrypted bigInt: <Very long number 2>
unencrypted bigInt: 0
unencrypted bigInt: 0
unencrypted bigInt: 0
unencrypted bigInt: 0
unencrypted bigInt: 0
unencrypted bigInt: 0
unencrypted bigInt: 0
unencrypted bigInt: 0
unencrypted bigInt: 0
unencrypted bigInt: 0
unencrypted bigInt: 0
unencrypted bigInt: 0
unencrypted bigInt: 0
unencrypted bigInt: 0
unencrypted bigInt: 0
unencrypted bigInt: 0
unencrypted bigInt: 0
unencrypted bigInt: 0
unencrypted bigInt: 0
decrypted frag <Very long number 3>
decrypted frag <Very long number 4
decrypted frag 0
decrypted frag 0
decrypted frag 0
decrypted frag 0
decrypted frag 0
decrypted frag 0
decrypted frag 0
decrypted frag 0
decrypted frag 0
decrypted frag 0
decrypted frag 0
decrypted frag 0
decrypted frag 0
decrypted frag 0
decrypted frag 0
decrypted frag 0
decrypted frag 0
decrypted frag 0
decrypted frag 0