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+---
+title: "replace_bls-key"
+date: 2022-07-11T15:17:04+09:00
+weight: 30
+pre: "<b>C. </b>"
+draft: false
+---
+
+{{< line_break >}}
+#### 4. Replace bls-nodekey on the CN - Except Bughole & Certik.
+
+> BLS-Nodekey is your Private key what you generate with Klay Tool.
+
+![CN](https://raw.githubusercontent.com/klaytn/klaytn-pre-cypress-setup-workshop/main/static/images/nodekey.png)
+
+In order to operate a node, a `bls-nodekey` is required. The KCN binary will create a new one for you if you do not have it. {{< line_break >}}
+If you have one, you need to put your `bls-nodekey` into the `data` directory.
+
+##### 1) Delete auto-generated bls-key
+{{< highlight html >}}
+$ mv /var/kcnd/data/bls-nodekey /var/kcnd/data/bls-nodekey_temp
+{{< /highlight >}}
+
+{{< line_break >}}
+
+##### 2) Create bls-nodekey file
+{{< highlight html >}}
+$ vi /var/kcnd/data/bls-nodekey
+{{< /highlight >}}
+
+
+{{< line_break >}}
+{{< line_break >}}
+
+{{< line_break >}}
+If you finish this step, please click the next button ```>``` on the right side of this page.