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NIST Randomness Beacon


NIST is implementing a prototype source of public randomness. The prototype (at uses two independent commercially available sources of randomness, each with an independent hardware entropy source and SP 800-90-approved components.

The Beacon is designed to provide unpredictability, autonomy, and consistency. Unpredictability means that users cannot algorithmically predict bits before they are made available by the source. Autonomy means that the source is resistant to attempts by outside parties to alter the distribution of the random bits. Consistency means that a set of users can access the source in such a way that they are confident that they all receive the same random string.


The Beacon will broadcast full-entropy bit-strings in blocks of 512 bits every 60 seconds. Each such value is time-stamped and signed, and includes the hash of the previous value to chain the sequence of values together. This prevents all, even the source, from retroactively changing an output packet without being detected. The beacon keeps all output packets and makes them available online. 

DRBG Beacon System Diagram

Tables of random numbers have probably been used for multiple purposes at least since the Industrial Revolution. The first published table appears to be by the English statistician L.H.C. Tippett. In the digital age, algorithmic random number generators have largely replaced these tables. The NIST Randomness Beacon expands the use of randomness to multiple scenarios in which the latter methods cannot be used. The extra functionalities stem mainly from three features. First, the Beacon-generated numbers cannot be predicted before they are published. Second, the public, time-bound, and authenticated nature of the Beacon allows a user application to prove to anybody that it used truly random numbers not known before a certain point in time. Third, this proof can be presented offline and at any point in the future. For example, the proof could be mailed to a trusted third party, encrypted and signed by an application, only to be opened if needed and authorized.

NIST encourages the community at large to research and publish novel ways in which this tool can be used. A few examples of applications are described below:

A Quantum Source:

Commercially available physical sources of randomness are adequate as entropy sources for currently envisioned applications of the Beacon. However, demonstrably unpredictable values are not possible to obtain in any classical physical context. Given this fact, our team established a collaboration with NIST physicists from the Physical Measurement Laboratory (PML). The aim is to use quantum effects to generate a sequence of truly random values, guaranteed to be unpredictable, even if an attacker has access to the random source. In August 2012, this project was awarded a multi-year grant from NIST's Innovations in Measurement Science (IMS) Program. IMS awards highly competitive projects designed to explore high-risk, leading-edge research concepts that anticipate future measurement and standards needs of industry and science. For more information on this collaboration see

NIST Beacon: A Public Randomness Service

End Date:


Lead Organizational Unit:



Rene Peralta

Mike Bartock
Larry Bassham
Joshua Bienfang
Harold Booth
Prof. Michael Fischer 
(Yale University Computer Science Dept)
Scott Glancy
Dr. Michaela Iorga
Stephen Jordan
John Kelsey
Emanuel Knill
Paulina Kuo
Yi-Kai Liu
Alan Migdall
Sae Woo Nam
Andrew Rukhin
Murugiah Souppaya
Xiao Tang