added final constraint

Author: tom zhou

src/com/iwebpp/crypto/TweetNacl.java

@@ -368,7 +368,7 @@ public static KeyPair keyPair_fromSecretKey(byte [] secretKey) {
 	 * @description 
 	 *   Secret Box algorithm, secret key
 	 * */
-	public static class SecretBox {
+	public static final class SecretBox {
 
 		private final static String TAG = "SecretBox";
 
@@ -1149,7 +1149,7 @@ private static int crypto_onetimeauth(
 	* Port of Andrew Moon's Poly1305-donna-16. Public domain.
 	* https://github.com/floodyberry/poly1305-donna
 	*/
-	public static class poly1305 {
+	public static final class poly1305 {
 
 		private byte[] buffer;
 		private int[] r;

src/com/iwebpp/crypto/TweetNaclFast.java

@@ -387,7 +387,7 @@ public static KeyPair keyPair_fromSecretKey(byte [] secretKey) {
 	 * @description 
 	 *   Secret Box algorithm, secret key
 	 * */
-	public static class SecretBox {
+	public static final class SecretBox {
 
 		private final static String TAG = "SecretBox";
 
@@ -1450,7 +1450,7 @@ public static int crypto_stream_xor(byte [] c,int cpos, byte [] m,int mpos, long
 	* Port of Andrew Moon's Poly1305-donna-16. Public domain.
 	* https://github.com/floodyberry/poly1305-donna
 	*/
-	public static class poly1305 {
+	public static final class poly1305 {
 
 		private byte[] buffer;
 		private int[] r;