Nearenough is a Java client of the Roughtime secure time synchronization protocol.

Nearenough aims to be 100% interoperable with the wider Roughtime ecosystem.

Roughtime is a protocol that aims to achieve rough time synchronisation in a secure way that doesn't depend on any particular time server, and in such a way that, if a time server does misbehave, clients end up with cryptographic proof of it. It was created by Adam Langley and Robert Obryk.

• Nearenough Github repo
• Roughtime project
• My blog posts describing Roughtime features and exploring the Nearenough API and details of Roughtime messages.
• Cloudflare's fantastic blog post and accompanying open-source project.

A publicly accessible Roughtime server is available at roughtime.int08h.com port 2002. The server's long-term public key is 016e6e0284d24c37c6e4d7d8d5b4e1d3c1949ceaa545bf875616c9dce0c9bec1 and can verified by querying the server's DNS TXT record:

$ dig -t txt roughtime.int08h.com
...
;; ANSWER SECTION:
roughtime.int08h.com.  1799  IN   TXT    "016e6e0284d24c37c6e4d7d8d5b4e1d3c1949ceaa545bf875616c9dce0c9bec1"

Gradle is used to build Nearenough. Run the tests:

$ ./gradlew test

And the examples:

$ ./gradlew nioExample
# or
$ ./gradlew nettyExample

See examples/NioClient.java and examples/NettyClient.java for examples of how to send a request to a Roughtime server and process the response.

If implementing your own client, the general idea is:

// The RoughTime server's long term public key, must be obtained a priori
byte[] serverLongTermPublicKey = { ... };

// Create client passing the server's long-term key
RoughtimeClient client = new RoughtimeClient(serverLongTermPublicKey);

// Construct a request, then encode it for transmission
RtMessage request = client.createRequest();
ByteBuf encodedRequest = RtWire.toWire(request);

// send encodedRequest using NIO, Netty, or some other mechanism...
RtMessage response = // ...and receive the response via NIO, Netty, etc ...

// Process the response
client.processResponse(response);

// Check the result
if (client.isResponseValid()) {
  Instant midpoint = Instant.ofEpochMilli(client.midpoint() / 1000L);
  System.out.println("midpoint: " + midpoint);
} else {
  System.out.println("Invalid response: " + client.invalidResponseCause().getMessage());
} 

See the javadocs in RoughtimeClient.java for more information.

Nearenough is stable.

• Protocol - Client protocol is feature complete.
• Client - Feature complete except for ecosystem-style request chaining.

• Stuart Stock, original author and current maintainer (stuart {at} int08h.com)
• Michal Tajchert (Github @tajchert)

If you would like to contribute to Nearenough, please see the guidelines in CONTRIBUTING.md.

Nearenough is Copyright (c) 2017-2018 int08h LLC. All rights reserved.

int08h LLC licenses Nearenough (the "Software") to you under the Apache License, version 2.0 (the "License"); you may not use this Software except in compliance with the License. You may obtain a copy of the License from the LICENSE file included with the Software or at:

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.