Examine source code of Encrypted Calculator

{
  "manifest_version": 2,
  "name": "Encrypted Calculator",
  "version": "1.8",
  "description": "A calculator extension with scientific functionality that uses encryption (AES) to quickly produce results in the browser.",
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "extension_icon16.png",
      "48": "extension_icon48.png",
      "128": "extension_icon128.png"
    }
  },
  "background": {
    "scripts": [
      "./scripts/background.js"
    ]
  },
  "icons": {
    "16": "extension_icon16.png",
    "48": "extension_icon48.png",
    "128": "extension_icon128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{d2ea3994-9e6d-425b-a28d-84e530e8e116}"
    }
  }
}