I would think DSpace, Fedora, and Eprint. DSpace is fairly easy to implement, which has embargo support in 1.6 (https://wiki.duraspace.org/display/DSTEST/Embargo ).
I have an article comparing DSpace and Fedora, but was written 6 years ago. DSpace has not been changed much, but Fedora is a different story. 
Yan
-----Original Message-----
From: Code for Libraries [mailto:[log in to unmask]] On Behalf Of Deng, Sai
Sent: Wednesday, October 20, 2010 10:33 AM
To: [log in to unmask]
Subject: [CODE4LIB] DL Systems (allowing search within documents and access restrictions)?

Hello, list,
Do you know the Digital Library systems which can search within the documents (e.g. PDFs) and handle access restrictions (e.g. DRM)?
Has any of you compared these DL systems?

Thanks for any information!
Sophie