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Date: Fri, 12 Jun 2015 12:42:46 -0700
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From: William Swanson <swansontec@gmail.com>
To: James Poole <james@microtrx.com>
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Cc: Bitcoin Dev <bitcoin-development@lists.sourceforge.net>
Subject: Re: [Bitcoin-development] Bip 32 Question
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The `n` is the curve order, as shown here:

https://en.bitcoin.it/wiki/Secp256k1

This step is necessary to keep you on the curve. The
secp256k1_ec_privkey_tweak_add function from libsecp256k1 handles this
automatically, but if you use OpenSSL or some non-EC math library, you
probably have to do it yourself.

-William

On Fri, Jun 12, 2015 at 11:22 AM, James Poole <james@microtrx.com> wrote:
> Looking at the BIP32 definition, I hit a line that I would appreciate
> clarification on.
>
> https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki
>
> Under the section "Private parent key =E2=86=92 private child key" there =
is a step:
>
> "The returned child key ki is parse256(IL) + kpar (mod n)."
>
> Can someone help me understand what "n" is in the context of this algorit=
hm?
> I very well could be looking right at it, but wanted to double check if I=
 am
> missing something.
>
> Thanks,
> James