String ekSha1Ref = getEKSHA1Ref(context);
//Construct a derivedKeyToken to be used
originalKey = skb.getSecretKey();
byte[] secret = originalKey.getEncoded();
DerivedKeyToken dkt = new DerivedKeyTokenImpl(offset, length, secret);
String dktId = secureMessage.generateId();
String nonce = Base64.encode(dkt.getNonce());
//get the symmetric key for encryption key from derivedkeyToken
try{
String jceAlgo = SecurityUtil.getSecretKeyAlgorithm(algorithm);
_symmetricKey = dkt.generateSymmetricKey(jceAlgo);