/usr/lib/x86_64-linux-gnu/libb64.so is in libb64-dev 1.2-3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libb64.so.0d
/usr/lib/x86_64-linux-gnu/libb64.so.0d