[Spice-devel] [virt-tools] Feature Request - Secure clipboard

gramps at ruggedinbox.com gramps at ruggedinbox.com
Sun Apr 26 08:52:55 PDT 2015

A secure clipboard is nice to have becuase there's no tradeoff between
convenience and safety. A vm can read the global clipboard only when you
want it. The Xen based Qubes has it and I don't see why KVM's spice and
libvirt can't. Here is how they did it:

slide 10 from


Challenge: copy clipboard from VM “Alice” to VM “Bob”, don’t let VM
“Mallory” to learn
its content in the meantime

Solved by introducing Qubes “global clipboard” to/from which copy/paste is
controlled by the user (Ctrl-Shift-C, Ctrl-Shift-V)

Requires 4 stages:
Ctrl-C (in the source VM)
Ctrl-Shift-C (tells Qubes: copy this VM buffer into global clipboard)
Ctrl-Shift-V (in the destination VM: tells Qubes: make global clipboard
available to this VM)
Ctrl-V (in the destination VM)
Ctrl-Shift-C/V cannot be injected by VMs (unspoofable key combo).

In practice almost as fast as traditional 2-stage copy-paste (don’t freak
out! ;)

More technical explanation


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