IO exception when encrypting

Question

hi guys,
i am trying to convert an image to a byte[] and then encypt. i have been able to convert to a byte array and have been able to get the private key to be encoded with base64 and output to the file. the problem is that when i run the program i get the following error.
Exception: java.io.IOException: closed
at javax.imageio.stream.ImageInputStreamImpl.checkClosed(ImageInputStreamImpl.java:90)
at javax.imageio.stream.FileImageInputStream.read(FileImageInputStream.java:85)
at javax.imageio.stream.ImageInputStreamImpl.read(ImageInputStreamImpl.java:135)
at Security.imageConvert(Security.java:37)
at Security.main(Security.java:147)
Please see the code below, any help would be great!
C4rter
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.PrintStream;
import javax.imageio.stream.FileImageInputStream;
import java.security.*;
import java.io.*;
import javax.crypto.*;
import sun.misc.*;
import java.lang.*;
public class Security{
public static void imageConvert( ) throws Exception {
try{
System.out.println("please select the file to encrypt");
BufferedReader fileInput = new BufferedReader(new InputStreamReader(System.in));
String filetoread = null;
filetoread = fileInput.readLine();
System.out.println("please select the file to save to");
BufferedReader fileOutput = new BufferedReader(new InputStreamReader(System.in));
String filetostore = null;
filetostore = fileOutput.readLine();
    FileImageInputStream input = new FileImageInputStream(new File(filetoread));
ByteArrayOutputStream output = new ByteArrayOutputStream();
PrintStream stream = new PrintStream(output);
byte[] buffer = new byte[1024];
byte[] data = null;
int numberBytesRead = 0;
while ((numberBytesRead = input.read(buffer)) != -1)
output.write(buffer, 0, numberBytesRead);
System.out.println("going to encrypt");
encrypt(buffer);
System.out.println("back to imageconvert");
FileOutputStream imageOut = new FileOutputStream(new File(filetostore));
System.out.println("sent to file");
output.close();
input.close();
} catch(Exception ex) {
System.out.println("Exception: " + ex);
ex.printStackTrace();
//public byte[] byteConvert(){}
public static byte[] encrypt(byte[] imageBytes) throws Exception {
System.out.println("in encrypt");
Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
PublicKey pubk = keyGenerator();
System.out.println("read out" + pubk);
cipher.init(Cipher.ENCRYPT_MODE, pubk);
byte[] encrypted = new byte[imageBytes.length];
System.out.println("Imagebyte length: " + imageBytes.length);
byte[] temp = new byte[53];
byte[] temp2 = null;
int x, y, z = 0;
int repeats = imageBytes.length/53;
System.out.println("Iterations: " + repeats);
for (z=0; z<repeats; z++) {
System.out.println("Iteration number: " + z);
int offset = z*53;
for (x=0; x<53; x++) {
temp[x] = (byte) imageBytes[offset+x];
temp2 = cipher.doFinal(temp);
for (y=0; y<53; y++) {
encrypted[offset+y] = (byte) temp2[y];
temp2 = null;
return encrypted;
//return cipher.doFinal(imageBytes);
public void decrypt(){}
public static PublicKey keyGenerator()throws Exception {
//try{
KeyPairGenerator keyGen = KeyPairGenerator.getInstance("rsa");
keyGen.initialize(512);
KeyPair KeyPair = keyGen.generateKeyPair();
PublicKey pubk = KeyPair.getPublic();
PrivateKey prvk = KeyPair.getPrivate();
saveprvKey(prvk);
//} catch(Exception ex) {
//System.out.println("Exception: " + ex);
//ex.printStackTrace();
return pubk;
private static void saveprvKey(PrivateKey prvky)throws Exception {
byte[] byteSeed = prvky.getEncoded();
BASE64Encoder encoder = new BASE64Encoder();
String seed = encoder.encodeBuffer(byteSeed);
FileWriter fw = new FileWriter("c:/privkey.txt");
fw.write(seed);
fw.close();
public static void main (String[] unused) throws Exception {
System.out.println("***********************************************");
System.out.println("***    Biometric Encrytion Program          ***");
System.out.println("***********************************************");
System.out.println("Please select a process");
System.out.println("e for encryption ");
System.out.println("d for decrytion");
boolean choose = false;
BufferedReader userInput = new BufferedReader(new InputStreamReader(System.in));
String choice = null;
choice = userInput.readLine();
if (choose = choice.equals("e")){
imageConvert();
System.out.println("Encryption");
else
System.out.println("Decryption");
//byteConvert();
}

Answer 1

hi sabre,
After going against what you said, i tried to get the RSA to work with encryption and decryption.
i have now seen the light and the error of my ways, i was wondering if you could give a brief explanation of the hybrid approach that you mentioned. and how easy would it be to doctor my code to allow for this,
Also would you recomend AES or DES for the Symmetric encryption?
cheers
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.PrintStream;
import java.security.interfaces.RSAPrivateKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.RSAPrivateKeySpec;
import javax.crypto.spec.SecretKeySpec;
import javax.imageio.stream.FileImageInputStream;
import java.security.*;
import java.io.*;
import javax.crypto.*;
import sun.misc.*;
import java.lang.*;
public class Security{
public static void imageConvert( ) throws Exception {
try{
System.out.println("please select the file to encrypt");
BufferedReader fileInput = new BufferedReader(new InputStreamReader(System.in));
String filetoread = null;
filetoread = fileInput.readLine();
System.out.println("please select the file to save to");
BufferedReader fileOutput = new BufferedReader(new InputStreamReader(System.in));
String filetostore = null;
filetostore = fileOutput.readLine();
FileImageInputStream input = new FileImageInputStream(new File(filetoread));
ByteArrayOutputStream output = new ByteArrayOutputStream();
PrintStream stream = new PrintStream(output);
byte[] buffer = new byte[1024];
byte[] data = null;
int numberBytesRead = 0;
while ((numberBytesRead = input.read(buffer)) != -1)
output.write(buffer, 0, numberBytesRead);
data = output.toByteArray();
System.out.println("encrytped" + buffer);
System.out.println("going to encrypt");
byte[] imageOutput = encrypt(data);
System.out.println("back to imageconvert");
System.out.println("encrytped" + buffer);
FileOutputStream imageOut = new FileOutputStream(new File(filetostore));
imageOut.write(imageOutput,0,imageOutput.length);
imageOut.close();
BASE64Encoder encoder = new BASE64Encoder();
String enc = encoder.encodeBuffer(imageOutput);
FileWriter fw = new FileWriter(filetostore);
fw.write(enc);
fw.close();
System.out.println("sent to file");
output.close();
input.close();
} catch(Exception ex) {
System.out.println("Exception: " + ex);
ex.printStackTrace();
public static void byteConvert()throws Exception{
    try{
System.out.println("please select the file to decrypt");
BufferedReader fileInput = new BufferedReader(new InputStreamReader(System.in));
String filetoread = null;
filetoread = fileInput.readLine();
FileInputStream fis = new FileInputStream(filetoread);
byte[] decrypt = new byte[fis.available()];
fis.read(decrypt);
fis.close();
String dec = new String(decrypt);
BASE64Decoder decoder = new BASE64Decoder();
byte[] byteSeed = decoder.decodeBuffer(dec);
// FileInputStream input = new FileInputStream(new File(filetoread));
// ByteArrayOutputStream inStream = new ByteArrayOutputStream();
// PrintStream stream = new PrintStream(inStream);
// PrintStream stream = new PrintStream(input);
// BASE64Decoder decoder = new BASE64Decoder();
// String dec = decoder.decodeBuffer(stream);
// String dec = new String(stream);
// byte[] decryptionBytes = inStream;
// byte[] s = decrypt(dec);
// decryptionBytes =(byte [])stream.readStream();
// stream.close();
// for(int i=0; i < decryptionBytes.length; i++)
    // System.out.print(decryptionBytes);
byte[] imageOutput = decrypt(byteSeed);
//byte[] imageOutput = decrypt(decrypt);
    }catch(Exception ex) {
System.out.println("Exception: " + ex);
ex.printStackTrace();
public static byte[] encrypt(byte[] imageBytes) throws Exception {
System.out.println("in encrypt");
Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
PublicKey pubk = keyGenerator();
System.out.println("read out" + pubk);
cipher.init(Cipher.ENCRYPT_MODE, pubk);
byte[] encrypted = new byte[imageBytes.length];
System.out.println("Imagebyte length: " + imageBytes.length);
byte[] temp = new byte[53];
byte[] temp2 = null;
int x, y, z = 0;
int repeats = imageBytes.length/53;
System.out.println("Iterations: " + repeats);
for (z=0; z<repeats; z++) {
System.out.println("Iteration number: " + z);
int offset = z*53;
for (x=0; x<53; x++) {
temp[x] = (byte) imageBytes[offset+x];
temp2 = cipher.doFinal(temp);
for (y=0; y<53; y++) {
encrypted[offset+y] = (byte) temp2[y];
temp2 = null;
return encrypted;
//return cipher.doFinal(imageBytes);
public static byte[] decrypt(byte[] bytesIn) throws Exception{
System.out.println("in decrypt");
Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
PrivateKey prvk = loadPrvkey();
System.out.println("read out" + prvk);
cipher.init(Cipher.DECRYPT_MODE, prvk);
//byte[] decodeData= cipher.doFinal(bytesIn);
byte[] decrypted = new byte[bytesIn.length];
System.out.println("Imagebyte length: " + bytesIn.length);
byte[] temp = new byte[64];
byte[] temp2 = null;
int x, y, z = 0;
int repeats = bytesIn.length/64;
System.out.println("Iterations: " + repeats);
cipher.update(decrypted);
for (z=0; z<repeats; z++) {
cipher.update(decrypted);
System.out.println("Iteration number: " + z);
int offset = z*64;
cipher.update(decrypted);     
for (x=0; x<64; x++) {
temp[x] = (byte) bytesIn[offset+x];
//cipher.update(temp);
temp2 = cipher.doFinal(temp);
for (y=0; y<64; y++) {
decrypted[offset+y] = (byte) temp2[y];
temp2 = null;
return decrypted;
//return decodeData;
/*the keyGenerator method is the method that is used to create the private and
*publickeys that are used for the encryption and decryption.
public static PublicKey keyGenerator()throws Exception {
//try{
KeyPairGenerator keyGen = KeyPairGenerator.getInstance("rsa");
keyGen.initialize(512);
KeyPair KeyPair = keyGen.generateKeyPair();
PublicKey pubk = KeyPair.getPublic();
PrivateKey prvk = KeyPair.getPrivate();
System.out.println("privatekey" + prvk);
saveprvKey(prvk);
//} catch(Exception ex) {
//System.out.println("Exception: " + ex);
//ex.printStackTrace();
return pubk;
/*The saveprvKey method is used to save the private key to the system. the encoded
*privatekey is encoded into base64 before it is stored.
private static void saveprvKey(PrivateKey prvky)throws Exception {
byte[] byteSeed = prvky.getEncoded();
BASE64Encoder encoder = new BASE64Encoder();
String seed = encoder.encodeBuffer(byteSeed);
FileWriter fw = new FileWriter("c:/privkey.txt");
fw.write(seed);
fw.close();
/*The loadPrvkey method is used to load the private key that is stored on the
*system into the program. this then allows for the private key to be used
*to decrypt the image byte array. The private key is decoded using base64
*and then the decoded version is returned
public static PrivateKey loadPrvkey() throws Exception{
FileInputStream fis = new FileInputStream("c:/privkey.txt");
byte[] encKey = new byte[fis.available()];
fis.read(encKey);
fis.close();
String seed = new String(encKey);
BASE64Decoder decoder = new BASE64Decoder();
byte[] byteSeed = decoder.decodeBuffer(seed);
//PrivateKey prvKey = getPrivate(byteSeed);
//PrivateKey prvKey = new PrivateKey(byteSeed);
KeyFactory rsaKeyFac = KeyFactory.getInstance("RSA");
PKCS8EncodedKeySpec encodedKeySpec = new PKCS8EncodedKeySpec(byteSeed);
RSAPrivateKey prvKey = (RSAPrivateKey)rsaKeyFac.generatePrivate(encodedKeySpec);
return prvKey;
/* the main method is where the program is run from, this main method will
* allow the user to choose between encryption and decryption with the entry
*of an e or d in the user input console then the method chosen will be
*called. it will either be imageConvert or Byteconvert.
public static void main (String[] unused) throws Exception {
System.out.println("***********************************************");
System.out.println("***    Biometric Encrytion Program          ***");
System.out.println("***********************************************");
System.out.println("Please select a process");
System.out.println("e for encryption ");
System.out.println("d for decrytion");
boolean choose = false;
BufferedReader userInput = new BufferedReader(new InputStreamReader(System.in));
String choice = null;
choice = userInput.readLine();
if (choose = choice.equals("e")){
imageConvert();
System.out.println("Encryption");
else
System.out.println("Decryption");
byteConvert();
}