Examine source code of Cipher

{
  "manifest_version": 2,
  "name": "Cipher",
  "version": "1.0.2resigned1",
  "description": "Encrypt text from context menu",
  "icons": {
    "48": "icons/cipher-48.png",
    "96": "icons/cipher-96.png"
  },
  "background": {
    "scripts": [
      "cipher.js"
    ]
  },
  "permissions": [
    "activeTab",
    "contextMenus",
    "clipboardWrite"
  ],
  "applications": {
    "gecko": {
      "id": "cipher@junquera.xyz"
    }
  }
}