BIP32 "hardened" paths (such with ' at the end) are not working correctly

[ok2]

The HD addresses (BIP32) seem not to be generated correctly when using the "hardened" (or called "private" before) path. Here an example:

When I use this BIP32 extended key and generate it on https://bip32.org like that (with derivation path m/0/0).

(I have used here the private key xprv9s21ZrQH143K4LFT94R8McbDHwwZELYANjUeVipBx1Nbm9P9Cipv6qmSjscnJSqe7pmn2G8duf9gyzX5tsrqG83ACX5dmEqsHUbo9q2bKJ2)

And generate the same on coinb.in then I get the same result:

But when I use the derivation path m/0'/0 like this:

Then coinb.in generates a different private key:

It seems, that the "hardened" path is not working correctly, probably it is also the reason, why I can not generate the same addresses in coinb.in like in bitcoin-cli, because bitcoin-cli seem to use only "hardened" paths. Another reason that in the current coinb.in UI it is not possible to use "hardened" indices, they are always appended like .../0, newer like .../0'. Probably an option for that or a possibility to specify start/end indices as 0' would be good.

[ok2]

I have now created a fix for it into pull request #228, what do you think about it?