DNS-Based Secured Email

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The NCCoE has released the draft version of NIST Cybersecurity Practice Guide SP 1800-6, DNS-Based Secured Email. Use the buttons below to view this publication in its entirety or scroll down for links to a specific section.

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Business Challenge

Email has become the dominant method of electronic communication for both private and public sector organizations, fueled by low costs and fast delivery.  Securing these transactions has been less of a priority, which is one reason why email attacks have increased.

Whether the goal is authentication of the source of an email message or assurance that the message has not been altered by or disclosed to an unauthorized party, organizations must employ some cryptographic protection mechanism. Economies of scale and a need for uniform security implementation drive most enterprises to rely on mail servers and/or Internet service providers (ISPs) to provide security to all members of an enterprise. Many current server-based email security mechanisms are vulnerable to, and have been defeated by, attacks on the integrity of the cryptographic implementations on which they depend. The consequences of these vulnerabilities frequently involve unauthorized parties being able to read or modify supposedly secure information, or introduce malware to gain access to enterprise systems or information. Protocols exist that are capable of providing needed email security and privacy, but impediments such as unavailability of easily implemented software libraries and operational issues stemming from some software applications have limited adoption of existing security and privacy protocols.


This project has resulted in NIST Special Publication 1800-6, “Domain Name Systems-Based Electronic Mail Security,” which illustrates how commercially available technologies can meet an organization’s needs to improve email security and defend against email-based attacks such as phishing and man-in-the-middle types of attacks.

This draft practice guide describes a proof of concept security platform that demonstrates trustworthy email exchanges across organizational boundaries and includes authentication of mail servers, signing and encryption of email, and binding cryptographic key certificates to the servers.

The goal of this project is to help organizations:

  • Encrypt emails between mail servers
  • Allow individual email users to digitally sign and/or encrypt email messages
  • Allow email users to identify valid email senders as well as send digitally signed messages and validate signatures of received messages

The example solution uses Domain Name System Security Extension (DNSSEC) protocol to authenticate server addresses and certificates used for Transport Layer Security (TLS) to DNS names.

The project's demonstrated security platform can provide organizations with improved privacy and security protection for users' operations and improved support for implementation and use of the protection technologies. The platform also improves the usability of available DNS security applications and encourages wider implementation of DNSSEC, TLS and S/MIME to protect electronic communications.

Collaborating Vendors

Organizations participating in this project submitted their capabilities in response to an open call in the Federal Register for all sources of relevant security capabilities from academia and industry (vendors and integrators). The following respondents with relevant capabilities or product components (identified as “Technology Partners/Collaborators” herein) signed a Cooperative Research and Development Agreement to collaborate with NIST in a consortium to build this example solution.

Fraunhofer IAO logo
Internet Systems Consortium logo
Microsoft logo
NLnet Labs logo
Secure64 logo