if (args.length != 3) {
System.err.println("Usage: java FileDecryptor infile outfile password");
return;
}
String infile = args[0];
String outfile = args[1];
String password = args[2];
if (password.length() < 8 ) {
System.err.println("Password must be at least eight characters long");
}
try {
FileInputStream fin = new FileInputStream(infile);
FileOutputStream fout = new FileOutputStream(outfile);
// create a key
byte[] desKeyData = password.getBytes();
DESKeySpec desKeySpec = new DESKeySpec(desKeyData);
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
SecretKey desKey = keyFactory.generateSecret(desKeySpec);
// Read the initialization vector
DataInputStream din = new DataInputStream(fin);
int ivSize = din.readInt();
byte[] iv = new byte[ivSize];
din.readFully(iv);
IvParameterSpec ivps = new IvParameterSpec(iv);
// use Data Encryption Standard
Cipher des = Cipher.getInstance("DES/CBC/PKCS5Padding");
des.init(Cipher.DECRYPT_MODE, desKey, ivps);
byte[] input = new byte[64];
while (true) {
int bytesRead = fin.read(input);
if (bytesRead == -1) break;
byte[] output = des.update(input, 0, bytesRead);
if (output != null) fout.write(output);
}
byte[] output = des.doFinal();
if (output != null) fout.write(output);
fin.close();
fout.flush();
fout.close();
}
catch (InvalidKeySpecException e) {
System.err.println(e);
}
catch (InvalidKeyException e) {
System.err.println(e);
}
catch (InvalidAlgorithmParameterException e) {
System.err.println(e);
}
catch (NoSuchAlgorithmException e) {
System.err.println(e);
e.printStackTrace();
}
catch (NoSuchPaddingException e) {
System.err.println(e);
}
catch (BadPaddingException e) {
System.err.println(e);
}
catch (IllegalBlockSizeException e) {
System.err.println(e);
}
catch (IOException e) {
System.err.println(e);
}
