Java RSA PKCS1 padding Help!

Question

I'm doing a client for my vb6 coded server, though in vb6 i use RSA padding PKCS1 with loading public and private key from PEM formated files,
it works in vb6, but in java. I have trouble recreating the rsa cryptation part for protocols to server.

Answer 1

I'm using a old c++ lib in vb6 since it doesnt really allow rsa to be simple.
Java; this stuff works to encryp / decrypt THOUGH trying to decrypt Rsa encrypted byte array from vb6, returns some error with was expecting zero at start, guessing it's just the java example thats not PKCS1 padding.
      * RSA:
     private static Cipher enc;
     private static Cipher dec;
     public static void loadrsa(String pub, String priv) {
          try {
                        //pub and priv, are file paths for the pem keys.
               byte[] pubKeyBytes  = getBytesFromFile(pub);
               byte[] privKeyBytes = getBytesFromFile(priv);
               KeyFactory keyFactory = KeyFactory.getInstance("RSA");
               X509EncodedKeySpec pubSpec = new X509EncodedKeySpec(pubKeyBytes);
               RSAPublicKey pubKey = (RSAPublicKey) keyFactory.generatePublic(pubSpec);
               PKCS8EncodedKeySpec privSpec = new PKCS8EncodedKeySpec(privKeyBytes);
               RSAPrivateKey privKey = (RSAPrivateKey) keyFactory.generatePrivate(privSpec);          
               enc = Cipher.getInstance("RSA");
               enc.init(Cipher.ENCRYPT_MODE, pubKey);
               dec = Cipher.getInstance("RSA");
               dec.init(Cipher.DECRYPT_MODE, privKey);
          } catch (Exception e) {
               System.out.println("loadrsa():::");
               System.out.println(e);
     public static byte[] RSAE(byte[] data) {
          try {
               return enc.doFinal(data);
          } catch (Exception e) {
               System.out.println("RSAE():::");
               System.out.println(e);
          return null;
     public static byte[] RSAD(byte[] data) {
          try {
               return dec.doFinal(data);
          } catch (Exception e) {
               System.out.println("RSAD():::");
               System.out.println(e);
          return null;
     private static byte[] getBytesFromFile(String filePath) throws IOException {
          File file = new File(filePath);
          InputStream is = new FileInputStream(file);
          long length = file.length();
          byte[] bytes = new byte[(int)length];
          int offset = 0;
          int numRead = 0;
          while (offset < bytes.length &&
                    (numRead=is.read(bytes, offset, bytes.length-offset)) >= 0) {
              offset += numRead;
          if (offset < bytes.length) {
              throw new IOException("Could not completely read file " + file.getName());
          is.close();
          return bytes;
     }