You could use hashpipe (https://github.com/jbenet/hashpipe), from Juan Benet (the author of IPFS). It simply checks that the input to the command matches a given hash, so you can do `curl <url> | hashpipe <hash> | sh`, and if the output of the curl command is different than expected it won't be passed in to `sh`.

Ironically the prebuilt binaries of hashpipe itself are provided without means of verification :I

So if you are going to use hashpipe, I think you should download it in source form, read it -- it's under 100 SLOC -- and then build it from source yourself. This way, you do that once and then in the future provided that you trust those sending you various scripts and binaries and the channel they used to provide the hash, all is well and no further manual verification is needed on your side of things ever again for any of those.

If an attacker can modify the output of the curl command (on the host or on the wire), cannot they also modify the value of the hash seen and copy-pasted by the end-user? I must be missing something...

As viraptor said, putting code into a public repository (e.g., debian packages); that way there should be a paper trail if the code is modified.

Beyond that, there's a simple matter of advertising: "Share your terminal (read-only)" may mislead some people about what is happening. A more accurate description would be "Give us control of your terminal (we promise we'll only let other people read it, not write anything)".

Imagine if this principle were applied to other software products. "Click here to download the Office installer, which will gain full admin-level access to your machine. We promise to only use that to install Office."

That would be awesome. Users might start to understand security.

Users don't read.

As usual, you can never be sure unless you read the code, luckily, it's very small: https://github.com/vitorbaptista/shellshare/blob/master/publ...

The only thing sent to shellshare's servers is the text in your bash terminal. There's no return channel for the servers to send commands back to the computer.

You could argue that you're giving control of the terminal because you're running a third-party executable, but that's the same for any executable you run.

Download it, audit the code, and then do python shellshare

> Download it, audit the code

Applies to your operating system as well, plus any firmware.

Boring, you need to live on the wild side a bit more :D