check number of bytes, allow custom value

launch4j.xml

@@ -24,11 +24,11 @@
     <runtimeBits>64/32</runtimeBits>
   </jre>
   <versionInfo>
-    <fileVersion>0.1.0.0</fileVersion>
+    <fileVersion>0.1.1.0</fileVersion>
     <txtFileVersion>0</txtFileVersion>
     <fileDescription>AES-256 Key Generator &amp; Checksum Calculator</fileDescription>
     <copyright>Andreas Erhard</copyright>
-    <productVersion>0.1.0.0</productVersion>
+    <productVersion>0.1.1.0</productVersion>
     <txtProductVersion>0</txtProductVersion>
     <productName>AES-256 Key Generator &amp;amp; Checksum Calculator</productName>
     <companyName>Andreas Erhard</companyName>

src/at/andaris/keyutil/CalculatorForm.java

@@ -43,7 +43,7 @@
  */
 public class CalculatorForm extends javax.swing.JFrame {
 
-    public static final String VERSION = "0.1.0";
+    public static final String VERSION = "0.1.1";
 
     /**
      * Creates new form ContactEditor
@@ -188,8 +188,13 @@ private void btnCalculateActionPerformed(java.awt.event.ActionEvent evt) {//GEN-
             return;
         }
 
+        int n = 3;
+
         try {
-            int n = Integer.parseInt(numberBytes);
+            n = Integer.parseInt(numberBytes);
+            if (n < 1 || n > 32) {
+                throw new NumberFormatException();
+            }
         } catch (NumberFormatException e) {
             JOptionPane.showMessageDialog(this, "Invalid number of bytes!");
 
@@ -198,7 +203,7 @@ private void btnCalculateActionPerformed(java.awt.event.ActionEvent evt) {//GEN-
 
         String result = "";
         try {
-            result = Calculator.calcCheckSumFromKey(key, 3);
+            result = Calculator.calcCheckSumFromKey(key, n);
         } catch (NoSuchAlgorithmException e) {
             JOptionPane.showMessageDialog(this, "Hash SHA-256 is not supported on your platform.");