Roughtime

A limitation of Trusted Execution Environments(TEE) is the lack of access to a trusted time source.

Even if a TEE secures communication with an NTP server, which is trusted to provide accurate time, an attacker controlling the network or hypervisor can delay response packets. Roughtime addresses this issue by incorporating nonces into the protocol between the client and the NTP server. Because the client-generated nonce is signed along with the server's response, the client can be assured that the Roughtime server generated the response after the request was sent.

Additionally, the client does not need to rely on a single server, as the protocol allows for contacting multiple servers to obtain cryptographic proof if a server is misrepresenting the time.