Performance between Java lib and C++ dll on Android

Question

I'm building an encryption application on Android. Using library encrypt in Java. But it's slowly during encrypt processing.

I think about using dll encrypt wrote by C++.

But does it actually make encrypt processing faster ?

If you have experience about that, please help me.

Answer 1

The only way to tell this is by profiling. C++ should be faster, but JNI overhead could slow it down. So could bad programming. Also note that faster isn't always better for encryption- there are attacks on encryption implementations that are based on detecting that the programmer saw certain optimizations (such as not performing a calculation in 1 branch of an if statement) that lets it guess the values of certain keybits. Take a well written, open source, debugged library over one that's faster. And never write your own encryption unless you're an expert- even if you write the algorithm perfectly you'll have side vector attacks like the one above in it.