Decode a JWT Workflow

In this tutorial, we will create a convert workflow that will decode a JSON Web Token (JWT).

Creating a Convert Workflow

To begin, navigate to the Workflows interface, select the Convert tab, and click the + New workflow button.

Next, rename the workflow by typing in the Name input field. You can also provide an optional description of the workflow's functionality by typing in the Description input field.

Nodes and Connections

To add nodes to the workflow, click on + Add Node button and then the + Add button of a specific node.

For this workflow, the overall node layout will be:

• The Convert Start node outputs $convert_start.data that represents the input that will undergo conversion.
• The JWT input will be passed to the JWT Decode node, which will extract the header and body segments of the JWT, decode them, and output them separately as $jwt_decode.header and $jwt_decode.payload.
• The Join node will concatenate the decoded header and body segments with a specified separator and output $join.data.
• Once the decoded segments have been processed by the Join node, the data will be output, and the workflow will end.

Decoding a JWT

1. Click on the JWT Decode node to access its editor and ensure the $convert_start.data is referenced as input data.

2. Close the editor window and click on the Join node to access its editor.

3. Reference $jwt_decode.header as the value of the Left (bytes) input data and $jwt_decode.payload as the value of the Right (bytes) input data.

4. Next, type in a . character in the Separator input field.

5. Close the editor window and click on the Convert End node to access its editor.

6. Reference $join.data as input data.

Once these steps are completed, close the editor window and click on the Save button to update and save the configuration.

Testing the Workflow

To test the workflow, add the following JWT in the Input text area:

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c

and click on the Run button.

To test the workflow, paste a valid JWT in the Input text area and click on the Run button. A message will appear notifying you that the workflow executed successfully.

The Result

The decoded and joined header and payload of the JWT will appear in the Output text area:

The full workflow is provided below, ready to be imported.

Full workflow

{
  "description": "Decodes the header and payload segments of a JWT.",
  "edition": 2,
  "graph": {
    "edges": [
      {
        "source": {
          "exec_alias": "exec",
          "node_id": 0
        },
        "target": {
          "exec_alias": "exec",
          "node_id": 2
        }
      },
      {
        "source": {
          "exec_alias": "exec",
          "node_id": 2
        },
        "target": {
          "exec_alias": "exec",
          "node_id": 3
        }
      },
      {
        "source": {
          "exec_alias": "exec",
          "node_id": 3
        },
        "target": {
          "exec_alias": "exec",
          "node_id": 1
        }
      }
    ],
    "nodes": [
      {
        "alias": "convert_start",
        "definition_id": "caido/convert-start",
        "display": {
          "x": -90,
          "y": 0
        },
        "id": 0,
        "inputs": [],
        "name": "Convert Start",
        "version": "0.1.0"
      },
      {
        "alias": "convert_end",
        "definition_id": "caido/convert-end",
        "display": {
          "x": 530,
          "y": 0
        },
        "id": 1,
        "inputs": [
          {
            "alias": "data",
            "value": {
              "data": "$join.data",
              "kind": "ref"
            }
          }
        ],
        "name": "Convert End",
        "version": "0.1.0"
      },
      {
        "alias": "jwt_decode",
        "definition_id": "caido/jwt-decode",
        "display": {
          "x": 120,
          "y": 0
        },
        "id": 2,
        "inputs": [
          {
            "alias": "data",
            "value": {
              "data": "$convert_start.data",
              "kind": "ref"
            }
          }
        ],
        "name": "JWT Decode",
        "version": "0.1.0"
      },
      {
        "alias": "join",
        "definition_id": "caido/join-two",
        "display": {
          "x": 330,
          "y": 0
        },
        "id": 3,
        "inputs": [
          {
            "alias": "left",
            "value": {
              "data": "$jwt_decode.header",
              "kind": "ref"
            }
          },
          {
            "alias": "right",
            "value": {
              "data": "$jwt_decode.payload",
              "kind": "ref"
            }
          },
          {
            "alias": "separator",
            "value": {
              "data": ".",
              "kind": "string"
            }
          }
        ],
        "name": "Join",
        "version": "0.1.0"
      }
    ]
  },
  "id": "786191d6-a205-4360-9122-715629645280",
  "kind": "convert",
  "name": "JWT Decode"
}