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Symmetric keygen: JsThemis #562

Merged
merged 5 commits into from
Dec 11, 2019
Merged

Symmetric keygen: JsThemis #562

merged 5 commits into from
Dec 11, 2019

Commits on Dec 6, 2019

  1. Symmetric keygen: JsThemis 

    Node.js native extensions and V8 are hard.

Initially it was expected that JsThemis has an interface similar to
WasmThemis. Something like this:

    class SymmetricKey extends Buffer {
        constructor(array) {
            if (array) {
                super(array)
            } else {
                super(generateNewKey())
            }
        }
    }

Note SymmetricKey is a class which inherits from Buffer. Now consider
the fact that JavaScript does not *really* have classes, it has objects,
functions, and prototypes, with EcmaScript 6 classes being a nice syntax
sugar on top of that.

It turned out to be not obvious how to implement JavaScript inheritance
from native JavaScript classes given the API provided by V8 (and I'm not
even talking about the outstanding quality of V8 documentation /s).

This is further complicated by the fact that all of the Buffer's
constructors are considered deprecated, with Buffer.alloc() and
Buffer.from() being the recommended way of constructing Buffers.

I'm in a bit of a loss here so effectively SymmetricKey is now

    function SymmetricKey(array) {
        if (array) {
            return Buffer.from(array)
        } else {
            return generateKeyBuffer()
        }
    }

This kinda works on the API level because classes are functions in
JavaScript, but it's not strictly correct as "new SymmetricKey()"
expression returns an instance of Buffer (not SymmetricKey). It's
fine since that's all API that we need at the moment, but it's not
clean. However, after spending around 4 hours trying to understand
how to do inheritance, I kinda gave up.

This should be enough for practical purposes for now. We will have
to get back to this issue if we would like to provide our own wrapper
over Buffer instances for all other keys, but for now it's good enough.

*fingers crossed*
    @ilammy
    ilammy committed Dec 6, 2019
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  2. Stricter length tests

    @ilammy
    ilammy committed Dec 6, 2019
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  3. More empty buffer checks

    @ilammy
    ilammy committed Dec 6, 2019
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  4. More instance tests 

    Let's make sure that we don't do anything silly in our Node.js extension
code and don't accidentally reuse the same objects or memory buffers.
    @ilammy
    ilammy committed Dec 6, 2019
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  5. fixup! More instance tests 

    JavaScript vOv Land of no compilation errors. (Though we could invest
into a linter...)
    @ilammy
    ilammy committed Dec 6, 2019
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