Low-level Bitcoin (opens in new tab)

This curve order limit actually introduces a small bias. You can choose a number greater than a curve order, but then it'll be taken modulo the order, so some incredibly small amount of numbers will be biased closer to zero. In practice the probability to hit such numbers is less than 2^-128, so you may easily skip all checks and take the number as is. Of course, nitpickers will nitpick and that's why in all standards that describe key and nonce generation (BIP32, RFC 6979 etc), you'll see boilerplate code that checks for such numbers and does some extra cumbersome computations just to avoid these from happening.

Excellent point, added as annotation, thanks!

Yes, you're right, numbers treatment is not exactly the same as in Bitcoin Core. The script interpreter supports only basics and it was implemented to show how Bitcoin Script works in general for another article [0].

But it was not clear from this text whether it's a complete implementation or not so it looks like a bug. I've added the annotation [1] and will update the interpreter in the future.

Of course if one wanted to use Bitcoin in real projects I'd rather recommend Bitcoin.js [2] but that's another topic.

Thanks for comment!

[0]: https://curiosity-driven.org/bitcoin-contracts

[1]: https://curiosity-driven.org/low-level-bitcoin#operators

[2]: http://bitcoinjs.org/

They already do that: http://www.righto.com/2014/02/ascii-bernanke-wikileaks-photo...

Also related: http://en.wikipedia.org/wiki/Illegal_number