Roughenough

Roughenough is a Roughtime secure time synchronization client and server implementation in Rust.

Roughenough's server and client are functionally complete and at feature parity with the reference C++ and Golang implementations.

Requires latest stable Rust to compile. Contributions welcome, see CONTRIBUTING for instructions and limitations for areas that could use attention.

Links

• Roughenough Github repo
• Original Roughtime project
• My blog posts giving a technical deep-dive into Roughtime and exploring details of on-the-wire Roughtime messages.
• Cloudflare's fantastic blog post and accompanying open-source project.

Building and Running

Rust 1.31 or above required

Roughenough uses 2018 edition features and requires Rust 1.31 or newer to build.

Building

# Build roughenough
$ cargo build --release

The client binary is target/release/roughenough-client. After building you can copy the binary and run on its own (no cargo needed) if you wish.

$ cp target/release/roughenough-client /usr/local/bin 

Using the Client to Query a Roughtime Server

$ target/release/roughenough-client roughtime.int08h.com 2002
Requesting time from: "roughtime.int08h.com":2002
Received time from server: midpoint="Oct 26 2018 23:20:44", radius=1000000, verified=No (merkle_index=0)

Validating Server Responses

Use the -p flag with the client to validate the server's response with its public key.

# The public key of 'roughtime.int08h.com' is stored in a DNS TXT record 
$ host -t TXT roughtime.int08h.com
roughtime.int08h.com descriptive text "016e6e0284d24c37c6e4d7d8d5b4e1d3c1949ceaa545bf875616c9dce0c9bec1"

# Validate the server response using its public key
$ target/release/roughenough-client roughtime.int08h.com 2002 -p 016e6e0284d24c37c6e4d7d8d5b4e1d3c1949ceaa545bf875616c9dce0c9bec1
Requesting time from: "roughtime.int08h.com":2002
Received time from server: midpoint="Oct 26 2018 23:22:20", radius=1000000, verified=Yes (merkle_index=0)

The verified=Yes in the output confirms that the server's response had a valid signature.

Server Configuration

There are two (mutually exclusive) ways to configure the Roughenough server:

1. A YAML file, or
2. Environment variables

The server accepts the following configuration parameters:

YAML Key	Environment Variable	Necessity	Description
interface	ROUGHENOUGH_INTERFACE	Required	IP address or interface name for listening to client requests
port	ROUGHENOUGH_PORT	Required	UDP port to listen for requests
seed	ROUGHENOUGH_SEED	Required	A 32-byte hexadecimal value used to generate the server's long-term key pair. This is a secret value and must be un-guessable, treat it with care. (If compiled with KMS support, length will vary; see Optional Features)
batch_size	ROUGHENOUGH_BATCH_SIZE	Optional	The maximum number of requests to process in one batch. All nonces in a batch are used to build a Merkle tree, the root of which is signed. Default is 64 requests per batch.
status_interval	ROUGHENOUGH_STATUS_INTERVAL	Optional	Number of seconds between each logged status update. Default is 600 seconds (10 minutes).
health_check_port	ROUGHENOUGH_HEALTH_CHECK_PORT	Optional	If present, enable an HTTP health check responder on the provided port. Use with caution, see Optional Features.
kms_protection	ROUGHENOUGH_KMS_PROTECTION	Optional	If compiled with KMS support, the ID of the KMS key used to protect the long-term identity. See Optional Features.

YAML Configuration

The table above lists the YAML keys available in the config file. An example:

interface: 127.0.0.1
port: 8686
seed: f61075c988feb9cb700a4a6a3291bfbc9cab11b9c9eca8c802468eb38a43d7d3

Provide the config file as the single command-line argument to the Roughenough server binary:

$ /path/to/roughenough-server /path/to/config.yaml

Environment Configuration

Roughenough can be configured via the ROUGHENOUGH_* environment variables listed in the table above. Start the server with a single ENV argument to have Roughenough configure itself from the environment. Example:

$ export ROUGHENOUGH_INTERFACE=127.0.0.1
$ export ROUGHENOUGH_PORT=8686
$ export ROUGHENOUGH_SEED=f61075c988feb9cb700a4a6a3291bfbc9cab11b9c9eca8c802468eb38a43d7d3
$ /path/to/roughenough-server ENV

Starting the Server

# Build roughenough
$ cargo build --release

# Via a config file
$ target/release/roughenough-server example.cfg
2018-07-25 00:05:09 INFO  [server] Roughenough server v1.0.5 starting
2018-07-25 00:05:09 INFO  [server] Long-term public key: d0756ee69ff5fe96cbcf9273208fec53124b1dd3a24d3910e07c7c54e2473012
2018-07-25 00:05:09 INFO  [server] Ephemeral public key: 25fd5dc31ceee241aed3e643534e95ed0609e9a20982a45ac0312a5f55e2cc66
2018-07-25 00:05:09 INFO  [server] Server listening on 127.0.0.1:8686

# Or using environment variables
$ export ROUGHENOUGH_INTERFACE=127.0.0.1
$ export ROUGHENOUGH_PORT=8686
$ export ROUGHENOUGH_SEED=f61075c988feb9cb700a4a6a3291bfbc9cab11b9c9eca8c802468eb38a43d7d3
$ target/release/roughenough-server ENV
2018-07-25 00:05:09 INFO  [server] Roughenough server v1.0.5 starting
2018-07-25 00:05:09 INFO  [server] Long-term public key: d0756ee69ff5fe96cbcf9273208fec53124b1dd3a24d3910e07c7c54e2473012
2018-07-25 00:05:09 INFO  [server] Ephemeral public key: 25fd5dc31ceee241aed3e643534e95ed0609e9a20982a45ac0312a5f55e2cc66
2018-07-25 00:05:09 INFO  [server] Server listening on 127.0.0.1:8686

The resulting binary is target/release/roughenough-server. After building you can copy the binary and run on its own (no cargo needed):

$ cp target/release/roughenough-server /usr/local/bin 

Stopping the Server

Use Ctrl-C or kill the process.

Optional Features

Roughenough has two opt-in (disabled by default) features that are enabled either A) via a config setting, or B) at compile-time.

• HTTP Health Check responder to facilitate detection and replacement of "sick" Roughenough servers.
• Key Management System (KMS) support to protect the long-term server identity using envelope encryption and AWS or Google KMS.

See OPTIONAL-FEATURES.md for details and instructions how to enable and use.

Limitations

Roughtime features not implemented by the server:

• On-line (while server is running) key rotation. The server must be restarted to generate a new delegated key.
• The Rougheough server depends on the host's time source to comply with the smeared leap-second requirement of the Roughtime protocol. A Roughenough server sourcing time from Google's public NTP servers would produce compliant smeared leap-seconds but time sourced from members of pool.ntp.org likely will not.
• Ecosystem-style response fault injection.

About the Roughtime Protocol

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.

Contributors

• Stuart Stock (stuart {at} int08h.com)
• Aaron Hill (aa1ronham {at} gmail.com)
• Peter Todd (pete {at} petertodd.org)

Copyright and License

Roughenough is copyright (c) 2017-2019 int08h LLC. All rights reserved.

int08h LLC licenses Roughenough (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.