try {
this.prf = Mac.getInstance(prfAlgo, "SunJCE");
} catch (NoSuchAlgorithmException nsae) {
// not gonna happen; re-throw just in case
InvalidKeySpecException ike = new InvalidKeySpecException();
ike.initCause(nsae);
throw ike;
} catch (NoSuchProviderException nspe) {
// Again, not gonna happen; re-throw just in case
InvalidKeySpecException ike = new InvalidKeySpecException();
ike.initCause(nspe);