/usr/share/acl2-7.2dfsg/books/projects/security/ is in acl2-books-source 7.2dfsg-3.
This file is owned by root:root, with mode 0o755.
..
/usr/share/acl2-7.2dfsg/books/projects/security/des-ghosh/
/usr/share/acl2-7.2dfsg/books/projects/security/des-ghosh/des-test.lisp
/usr/share/acl2-7.2dfsg/books/projects/security/des-ghosh/des.acl2
/usr/share/acl2-7.2dfsg/books/projects/security/des-ghosh/des.lisp
/usr/share/acl2-7.2dfsg/books/projects/security/jfkr/
/usr/share/acl2-7.2dfsg/books/projects/security/jfkr/cert.acl2
/usr/share/acl2-7.2dfsg/books/projects/security/jfkr/diffie-helman.lisp
/usr/share/acl2-7.2dfsg/books/projects/security/jfkr/encryption.lisp
/usr/share/acl2-7.2dfsg/books/projects/security/jfkr/jfkr.lisp
/usr/share/acl2-7.2dfsg/books/projects/security/jfkr/random.lisp
/usr/share/acl2-7.2dfsg/books/projects/security/sha-2/
/usr/share/acl2-7.2dfsg/books/projects/security/sha-2/sha-2.lisp
/usr/share/acl2-7.2dfsg/books/projects/security/util/
/usr/share/acl2-7.2dfsg/books/projects/security/util/byte-operations.lisp