yclip

yclip implements a client-server model for sharing clipboard content. Invoke yclip to start a server locally; it will log a command in the form yclip <host>:<port> that you can run from elsewhere on the network to connect. Once connected, text/images copied on one machine will be instantly* pastable on the other!

Run yclip --help for the options:

Usage: yclip [OPTIONS] [SOCKET]

Arguments:
  [SOCKET]  Connect to the yclip server running on this socket address

Options:
  -i, --poll-interval <POLL_INTERVAL>  Frequency in ms with which to actually poll for
                                       clipboard changes (see README) [default: 10000]
  -p, --password <PASSWORD>            Encrypt clipboards using this password. Compile with
                                       the "force-secure" feature enabled to make this
                                       mandatory
  -v, --verbose...                     Increase verbosity (defaults to INFO and above)
  -h, --help                           Print help
  -V, --version                        Print version

* yclip is cross-platform.

On Windows, we can subscribe to WM_CLIPBOARDUPDATE events which are triggered whenever the clipboard changes. Easy!

On MacOS we can't sign up to be notified on clipboard changes. Instead, we have to poll the changeCount on NSPasteBoard and check if it's increased since last time. This means there's actually work to do to detect changes; I've set the default poll interval to be 200ms but if you find this is using up too many CPU cycles then you can reduce the frequency via the YCLIP_MACOS_POLL_INTERVAL_MILLIS environment variable.

On X11 linux systems, the situation is similar to Windows; in this case we can subscribe to the relevant XFIXES events, which are issued whenever someone asserts ownership of the clipboard. Sadly this isn't a catch-all; the current clipboard owner can change its contents without telling the X server about it (although this is against the ICCCM rules!) and so we'd miss it. As a safety measure, yclip polls the clipboard every so often (10s by default, adjust with the -i flag) and sees if it's changed.

On Wayland, uhhh... I have no idea how Wayland works.

Installation

Install using cargo with cargo install yclip. If you want to make password-encryption mandatory, specify --features force-secure.

Encryption

yclip uses a ChaChaPoly1305 encryption scheme, with keys derived from the user-provided password via the NNpsk0 Noise protocol. Even without a password, network bytes will still be encrypted - it's just that anyone will be able to connect to your clipboard!

Testing

I've implemented a fuzzer that simulates a client and a server communicating via an in-memory channel, testing that the clipboards are synced as expected. It hasn't failed yet! Run it yourself with cargo +nightly fuzz run --release local (this requires a nightly release of Cargo).