/usr/lib/x86_64-linux-gnu/libstrophe.so is in libstrophe-dev 0.9.1-1+b1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libstrophe.so.0.0.0
/usr/lib/x86_64-linux-gnu/libstrophe.so.0.0.0