{
  "method": "GetChallenge",
  "params": {
    "init": "<pssh as base64>",
    "cert": "<service certificate as base64>"
  },
  "token": "<user key from authorized_users.txt>"
}

{
  "status_code": 200,
  "message": {
    "session_id": "<unique session uuid>",
    "challenge": "<license request as base64>"
  }
}

{
  "method": "GetKeys",
  "params": {
    "session_id": "<unique session uuid>",
    "cdmkeyresponse": "<license response as base64>"
  },
  "token": "<user key from authorized_users.txt>"
}

{
  "status_code": 200,
  "message": {
    "keys": [
      {
        "kid": "<key id as hex>",
        "key": "<key as hex>"
      },
      {
        "kid": "<key id as hex>",
        "key": "<key as hex>"
      },
      ...
    ]
  }
}

{
  "status_code": 4XX|5XX,
  "message": "<error description>"
}