/usr/include/asio/ssl/detail/ is in libasio-dev 1:1.10.6-3.
This file is owned by root:root, with mode 0o755.
..
/usr/include/asio/ssl/detail/buffered_handshake_op.hpp
/usr/include/asio/ssl/detail/engine.hpp
/usr/include/asio/ssl/detail/handshake_op.hpp
/usr/include/asio/ssl/detail/impl/
/usr/include/asio/ssl/detail/impl/engine.ipp
/usr/include/asio/ssl/detail/impl/openssl_init.ipp
/usr/include/asio/ssl/detail/io.hpp
/usr/include/asio/ssl/detail/openssl_init.hpp
/usr/include/asio/ssl/detail/openssl_types.hpp
/usr/include/asio/ssl/detail/password_callback.hpp
/usr/include/asio/ssl/detail/read_op.hpp
/usr/include/asio/ssl/detail/shutdown_op.hpp
/usr/include/asio/ssl/detail/stream_core.hpp
/usr/include/asio/ssl/detail/verify_callback.hpp
/usr/include/asio/ssl/detail/write_op.hpp