Allow changing of data size in ByteContainer.setBytes(byte[], short, …

…short).

The motivation for this patch is github-af/SmartPGP#40.

However, this workaround avoids looking at the underlying problem:
ECKeyImpl(byte, short) should not initialize the DomainParameters (according to its own docs), but does.
This leads to problems with NIST P-521 because the default parameter for b has a leading zero bit that gets stripped, leading to a change in data size, when SmartPGP later sets b explicitly with the leading zero bit intact.

src/main/java/com/licel/jcardsim/crypto/ByteContainer.java

@@ -106,7 +106,7 @@ public void setBytes(byte[] buff) {
      * @param length length of data in byte array
      */
     public void setBytes(byte[] buff, short offset, short length) {
-        if (data == null) {
+        if (data == null || this.length != length) {
             switch (memoryType) {
                 case JCSystem.MEMORY_TYPE_TRANSIENT_DESELECT:
                     data = JCSystem.makeTransientByteArray(length, JCSystem.CLEAR_ON_DESELECT);