code:     private void testModified()
          throws Exception
      {
          ECNamedCurveParameterSpec namedCurve = ECNamedCurveTable.getParameterSpec("P-256");
          org.bouncycastle.jce.spec.ECPublicKeySpec pubSpec = new org.bouncycastle.jce.spec.ECPublicKeySpec(namedCurve.getCurve().createPoint(PubX, PubY), namedCurve);
          KeyFactory kFact = KeyFactory.getInstance("EC", "BC");
          PublicKey pubKey = kFact.generatePublic(pubSpec);
          Signature sig = Signature.getInstance("SHA256WithECDSA", "BC");
  
          for (int i = 0; i != MODIFIED_SIGNATURES.length; i++)
          {
              sig.initVerify(pubKey);
  
              sig.update(Strings.toByteArray("Hello"));
  
              boolean failed;
  
              try
              {
                  failed = !sig.verify(Hex.decode(MODIFIED_SIGNATURES[i]));
                  System.err.println(ASN1Dump.dumpAsString(ASN1Primitive.fromByteArray(Hex.decode(MODIFIED_SIGNATURES[i]))));
              }
              catch (SignatureException e)
              {
                  failed = true;
              }
  
              isTrue("sig verified when shouldn't: " + i, failed);
          }
      }
  
  