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About SELS

Every day, important discussions take place over email lists that participants would like to be kept confidential. But, because these communications usually take place on unencrypted, plain text email lists, their contents can be intercepted and read by anyone with access to the servers or networks — from system administrators to intruders.

The Security Research and Development Group at the National Center for Supercomputing Applications (NCSA) has developed a software solution to protect such discussions, called SELS (Secure Email List Services), and is looking for communities and organizations to user-test it. The software provides email discussion lists with the same level of security that PGP or S/MIME software provides for encrypted communication between individuals. SELS provides digital signature and encryption capabilities while ensuring that neither the list server nor outsiders have access to plain text emails.

SELS is open-source software that can be downloaded and installed in simple and well-documented steps. For interested groups, NCSA can host lists in our virtualized machine room that are easy to use and secure from unwanted readers.

How does SELS work?

SELS is based on the Open PGP (Pretty Good Privacy) standard. When users subscribe to a SELS-capable email list, they are each assigned a pair of digital keys. One key is used to open and read messages. The other, a proxy key stored in the list server’s key management system (or keyring), is used to re-encrypt every encrypted and signed email that member sends to the list. That way, even if the list server or intermediary network is compromised, the email content is not visible to the attacker.

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List participants don’t have to install custom email clients to use SELS. Commonly available plugins from GNU Privacy Guard (GnuPG, an open source implementation of PGP) provide compatibility with several commonly used email clients, including Mozilla Thunderbird, MacMail, Microsoft Outlook 2003, Mutt, and Emacs.

SELS has been developed with open-source components: GnuPG and Bouncy Castle cryptographic libraries, Mailman email list manager, Sendmail MTA, Python, and GnuPG plugins.

Who should use SELS?

Any group, community, or organization that needs to provide a secure email discussion list for its members should consider adopting SELS. Currently, SELS is being tested and used by cybersecurity professionals at NCSA and other NSF-supported large-scale computing facilities who detect, respond to, and prevent intrusions into thousands of systems used for research and development, including many of the world’s fastest supercomputers.

There are many groups who could benefit by using SELS:

  • System administrators and security professionals engaged in site security and incident response.
  • Academic researchers collaborating on a confidential project or proposal.
  • Companies wishing to safeguard online discussions involving proprietary information.
  • Financial institutions collecting or disseminating sensitive information or conducting private transactions.
  • Healthcare organizations needing to communicate quickly and securely with medical personnel during an emergency.
  • Educators interested in providing their students with a hands-on demonstration of encrypted communication and practical uses of cryptography.

How can we start using SELS?

To get started, you can apply for an email list hosted on NCSA’s SELS service. The SELS service will assign a pair of dedicated virtual machines for your list, hosted on two separate physical rack servers. The virtualized environment provides isolation for your list, and the two dedicated servers—primary and backup—provide redundancy and monitoring.

AELS service

Or you can download the SELS software to create your own secure list servers. Our website includes detailed installation instructions and FAQ.


Want to learn more about SELS or apply for a list? Contact the SELS team ( or call Dr. Himanshu Khurana (217-244-8680) for more information.

The SELS Team members are:

  • Himanshu Khurana, Principal Investigator
  • Jim Basney, Principal Investigator
  • Rakesh Bobba
  • Joe Muggli
  • Meenal Pant , Lead Developer
  • Kathleen Ricker, Media and Communications
SELS is supported by the National Center for Secure Systems Research (NCASSR), led by the National Center for Supercomputing Applications (NCSA) at the University of Illinois and funded by the Office of Naval Research.

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