Permissions

Each blockchain space can be configured to allow only access for particular set of transaction creators.

For example:

"permission_sets": [
    {
      "height": 0,
      "permissions": [
        {
          "path": "space",
          "public_key": "Ud8SI+nIX/XrPss2DEM1B2tdxu0v9NvuuAdABfUMrZk="
        }
      ]
    }
  ]

Owner of public key Ud8SI+nIX/XrPss2DEM1B2tdxu0v9NvuuAdABfUMrZk= has write access to space space starting from the first block.