# JSON Web Token (JWT)

### JSON Web Token (JWT) **in simple words**

It is a JSON object defined in the RFC 7519 open standard. It is a safe method of exchanging information and representing claims with a high level of security. If you enable it, only authorized requests will proceed.

{% hint style="info" %}
JSON Web Token (JWT) is available within the [Self-Hosted Cluster of Nodes](/self-hosted-cluster/self-hosted-cluster-of-nodes.md) offering.
{% endhint %}

### Apply JWT

Follow our step-by-step instructions to send JWT requests on RPC Fast.

#### Generate RSA-256 keys

RS256 is an asymmetrical key. After creating one, you receive both public and private keys. You will use the private one to create a signature and the public one to check its authenticity.

```
# generate rsa key
openssl genrsa -out jwtRSA256-private.pem 2048
openssl rsa -in jwtRSA256-private.pem -pubout -outform PEM -out jwtRSA256-public.pem
```

#### Enable JWT in RPC Fast

1. Login -> Dashboard -> App Page -> Settings
2. Tap ‘Add token’ in the JWT Token section and type the public RS256 key from the previous step.
3. Clicking on ‘Add’ to get a public ID

   <figure><img src="/files/PCGcH04uF5bbsifSIclu" alt=""><figcaption></figcaption></figure>

#### Generate the JSON Web Token

You should add JWT to all headers of requests to enable its work. To create a full-fledged JSON Web Token, you must fill out HEADER, PAYLOAD, and SIGNATURE cells.

| Field | Description                              | Example                              |
| ----- | ---------------------------------------- | ------------------------------------ |
| alg   | Write the signing algorithm you apply    | RS256                                |
| typ   | Fill out the token type                  | JWT                                  |
| kid   | Write your key id from the previous step | 10e03c88-098d-47cb-b451-a67f2137fqcf |

#### Payload

| Field | Description                                             | Example     |
| ----- | ------------------------------------------------------- | ----------- |
| aud   | Who can operate with this token                         | rpcfast.com |
| exp   | The validity time in a unix format (24 hours maximally) | 1656907527  |

{% hint style="info" %}
Use an epoch converter to receive a UNIX timestamp from a human-readable one or apply a unified command.
{% endhint %}

#### Signature

1. Encode a header.
2. Encode a payload.
3. Encode an algorithm from the title.
4. Take it all together and sign via the specific command.

```
# To encode a signature
sig=`echo -n "$header.$payload" | openssl dgst -sha256 -binary -sign jwtRSA256-private.pem  | openssl enc -base64 | tr -d '\n=' | tr -- '+/' '-_'`
```

#### JSON Web Token

Now you have your JSON Web Token! It looks like an encoded header, signature, and payload.

```
# JWT = header.payload.signature
jwt=`echo $header.$payload.$sig`
echo $jwt
```

You will need a debugger to verify it.

### Sending requests with JSON Web Token

Add JWT to the request header entry to proceed with it correctly.

### What should I do with a wrong JWT?

If you try sending requests with a wrong JWT or without it after enabling, a program will show the error 401 status code (security troubles). Disable JWT or enter the right one to continue operations.

```
{"error":"invalid payload or JWT configuration"}
```

### Key rotation support

PRC Fast is OK with key rotation. All you need to do is to upload a new one.


---

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