Dark fibre runs through car parks: why Layer 1 encryption is not a luxury

Organisations that lease or own dark fibre often regard that
connection as private infrastructure. Their own fibre, their own data,
their own management. What is often underestimated, however, is that the physical cable runs
through infrastructure that you do not manage, beneath streets, through
building service rooms, via multi-storey car parks and
cable ducts in the public domain. And anyone with physical access to
the fibre has access to the data travelling over it.