3. Key Agreement - These keys are used during secure communication to encrypt some data for the DID.
4. Capability Invocation - These keys are able to modify the DID Document, i.e. add new or remove existing keys, add/remove service endpoints, controllers, etc.
3. 密钥协议 - 这些密钥用于安全通信期间为 DID 加密某些数据。
4. 能力调用 - 这些键能够修改 DID 文档，即添加新的或删除现有的键，添加/删除服务端点、控制器等。