First, it builds a secure repository, which stores objects, acl objects and encrypted keys.
The repo is /home/lanyang
All commands except the following six executables, cannot access objects in the repo. (Executables are generated in /home/security-ly2331)
The six executables are:
1. objput -u username -k passphrase objname

2. objget -u username -k passphrase objname

3. objlist -u username [-l]

4. objsetacl -u username -g groupname objname

5. objgetacl -u username -g groupname objname

6. objtestacl -u username -g groupname -a access objname

For each command, username and groupname are checked, and for objput and objget, passphrase is also checked.
Detailed description about the project can refer to the following website.
1. https://www.cs.columbia.edu/~smb/classes/f14/pgm0.txt
2. https://www.cs.columbia.edu/~smb/classes/f14/pgm1.txt
3. https://www.cs.columbia.edu/~smb/classes/f14/pgm2.txt
4. https://www.cs.columbia.edu/~smb/classes/f14/pgm3.txt