Fix discrepancies between JS and Native implementations

[junderw]

Fixes #5

@yuki-js Please review.

[junderw]

I tested the native implementation manually for acceptable values.

Native impl accepted truthy values ( 0, '', etc. were false, 57, 'abc', etc. were true) So the js impl will match that and allow truthy values and not perform strict type checks on the strict parameter.

[yuki-js]

C++ implementation normalizes if strict. https://github.com/bitcoinjs/tiny-secp256k1/blob/9f07a89d5d9838628e34ac76db9ce64d9d1d3372/native/addon.cpp#L343

[junderw]

C++ implementation normalizes if strict. https://github.com/bitcoinjs/tiny-secp256k1/blob/9f07a89d5d9838628e34ac76db9ce64d9d1d3372/native/addon.cpp#L343

No. It normalizes if NOT strict.

The reason why is because the C library we call is ALWAYS strict (will return false if S value is high).

The normalization function just makes sure the s value is low.

• CPP: If not strict. We will fix the S value for you, because the library is always stict.
• JS: Our verify function is not strict, so if strict, we return false when high S (to make it strict).

It's very hard to understand..... even for me.

[yuki-js]

Oh, I made a mistake. " if NOT strict" is correct.