`Network error: broken pipe` when running tarsnap-keygen

[Carl van Tonder <carl@supervacuo.com>]

Hi folks,

Started getting set up with Tarsnap today and have run into an odd
error:

    # ./tarsnap-keygen --keyfile /etc/tarsnap.key --user my@email.com -
    -machine box
    Enter tarsnap account password: 
    tarsnap-keygen: Network error: Broken pipe
    tarsnap-keygen: Callbacks uninitialized
    tarsnap-keygen: Error registering with server

(with `my@email.com` and `box` replaced with actual values)

Password is definitely correct (can use it to log in on the website).

Environment is CentOS 6, openssl-1.0.1e-30.el6.8.x86_64.

Any thoughts on what the cause might be, or how to get more debugging
info about what's going wrong?

Cheers,

Carl