/usr/lib/libboinc_crypt.so is in libboinc-app-dev 7.2.42+dfsg-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/libboinc_crypt.so.7.2.42
/usr/lib/libboinc_crypt.so.7.2.42