{
  "content": {
    "algorithm": "m.megolm.v1.aes-sha2",
    "rotation_period_ms": 604800000,
    "rotation_period_msgs": 100
  },
  "event_id": "$WLGTSEFJJKJ:localhost",
  "origin_server_ts": 1476648761524,
  "sender": "@example:localhost",
  "room_id": "!Cuyf34gef24t:localhost",
  "state_key": "",
  "type": "m.room.encryption"
}