# Authentication

To obtain write privileges to interact with the NxtFi blockchain, each user/entity must generate a key pair using the RSA-PSS specification.

After the key-pair generation process is successful, according to the Proof-of-Authority mechanism, every PubKey needs to be approved by a higher hierarchy authenticated key-pair before it can interact with NxtFi in any way. 

Higher hierarchy key-pairs can only grant or revoke permissions, and are like parent elements. However, they will never be able to sign on behalf of other key-pairs.

{% hint style="info" %}
**IMPORTANT**: To write new blocks on TestNet blockchain either through playground or directly with the API, an administrator must first register your public key and release the necessary permissions. 
{% endhint %}

## Key-pair generation

The generation of a public-private key pair is done as follows in Javascript:

{% tabs %}
{% tab title="Javascript" %}

```javascript
window.crypto.subtle.generateKey(
    {
        name: "RSA-PSS",
        modulusLength: 2048, //can be 1024, 2048, or 4096
        publicExponent: new Uint8Array([0x01, 0x00, 0x01]),
        hash: {name: "SHA-256"}, //can be "SHA-1", "SHA-256", "SHA-384", or "SHA-512"
    },
    false, //whether the key is extractable (i.e. can be used in exportKey)
    ["sign", "verify"] //can be any combination of "sign" and "verify"
)
.then(function(key){
    //returns a keypair object
    console.log(key);
    console.log(key.publicKey);
    console.log(key.privateKey);
})
.catch(function(err){
    console.error(err);
}); 
```

{% endtab %}
{% endtabs %}

## Request permission for your key

Currently, authorization for new keys is done manually. Please contact the[ NxtFi administrator](https://nxtfi.org/nxtfi-hub/) to request the necessary permissions to write new blocks.


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```
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```

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