<p><code>UNKNOWN</code> is the serialized compressed public key for <code>ki</code>. <code>ki</code> is the private keys, so compute the public key for it and serialize it in compressed form.</p>

CC BY-SA 4.0
2021-08-05T18:02:10.197Z
thx, can you say what formula i need to use for it ? ki * G where G is 0279BE667EF9DCBBAC55A06295CE870B07029BFCDB2DCE28D959F2815B16F81798?
Gabriel
CC BY-SA 4.0
2021-08-06T02:18:00.397Z
@Gabriel Yes, that is the correct formula and value for G
Ava Chow
CC BY-SA 4.0
2021-08-06T17:29:49.900Z
but the formula as I understand it is conditional? 
and a rough multiplication will not give any result?
Gabriel
CC BY-SA 4.0
2021-08-06T17:45:14.097Z
G is an elliptic curve point. It's standard elliptic curve point multiplication which is different from integer multiplication. The algorithms for that are more complicated, but there's plenty of literature on elliptic curve math that you can search for.
Ava Chow
CC BY-SA 4.0
2021-08-07T01:31:37.760Z
If possible, tell me articles about the literature, about this, where it is possible to explain step by step the course of actions of turning a private key into points on the eleptic curve
Gabriel
CC BY-SA 4.0
2021-08-05T17:28:32.237Z
2021-08-05T17:28:32.237Z
Ava Chow
<p>After derive parent key i have IL, IR and pIL</p>
<p>Then i get ki:</p>
<pre><code>curve_n = 'fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141';

ki = remainder((pIL + priv), curve_n);
</code></pre>
<p>I know that parentFingerpring is:</p>
<pre><code>parentFingerprint = slice(rdm160(sha256(UNKNOW)), 4);
</code></pre>
<p>what varable or operation must be instead of UNKNOW?</p>

<bip32-hd-wallets>
How get fingerprint after derive parent key?
Gabriel
# How get fingerprint after derive parent key?

(Asked by: username_0 on 2021-08-05)

After derive parent key i have IL, IR and pIL

Then i get ki:

```
curve_n = 'fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141';

ki = remainder((pIL + priv), curve_n);

```

I know that parentFingerpring is:

```
parentFingerprint = slice(rdm160(sha256(UNKNOW)), 4);

```

what varable or operation must be instead of UNKNOW?

**Tags:** bip32-hd-wallets


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## 1 answers

### Answer by username_1 on 2021-08-05. Score: 1 | Accepted answer

`UNKNOWN` is the serialized compressed public key for `ki`. `ki` is the private keys, so compute the public key for it and serialize it in compressed form.

> **Comments:**
> **username_0**: thx, can you say what formula i need to use for it ? ki * G where G is 0279BE667EF9DCBBAC55A06295CE870B07029BFCDB2DCE28D959F2815B16F81798?  
> **username_1**: @username_0 Yes, that is the correct formula and value for G  
> **username_0**: but the formula as I understand it is conditional?  and a rough multiplication will not give any result?  
> **username_1**: G is an elliptic curve point. It's standard elliptic curve point multiplication which is different from integer multiplication. The algorithms for that are more complicated, but there's plenty of literature on elliptic curve math that you can search for.  
> **username_0**: If possible, tell me articles about the literature, about this, where it is possible to explain step by step the course of actions of turning a private key into points on the eleptic curve  

---

