If you're wanting to build an app that has cryptographic capabilities, you might run into some trouble if you're expecting to be able to do it in JavaScript without touching any ObjC/Java (an expectation that I don't believe to be highly unreasonable)
React Natives's JavaScript runtime doesn't support WebCrypto. People have resorted to browserifying Node's crypto module (and the rest of Node's built-in modules, as a result) which gives you everything besides a RNG (a RNG cannot be browserified for obvious reasons).
I guess what I'm saying is: I sure hope you aren't trying to do anything too exotic with React Native without first getting ankle-deep in some native code.
React Natives's JavaScript runtime doesn't support WebCrypto. People have resorted to browserifying Node's crypto module (and the rest of Node's built-in modules, as a result) which gives you everything besides a RNG (a RNG cannot be browserified for obvious reasons).
I guess what I'm saying is: I sure hope you aren't trying to do anything too exotic with React Native without first getting ankle-deep in some native code.