Contents7 sections

ARPANET encryption devices

Tools

Actions

General

Recent changes
Related articles
Random discovery

This article

Reading time: 2 min
Topic: Computer Science
Quality: Start-class
Views: 23 in 14 days

Last edited: 24 Oct 2026

Key concepts

The articles this one links to most, weighted towards the introduction.

Print/export

Printable version

In other projects

Wikidata item

General

Recent changes
Related articles
Random discovery

This article

Reading time: 2 min
Topic: Computer Science
Quality: Start-class
Views: 23 in 14 days

Created: 17 Jul 2019
History: 21 edits; 16 contributors; 1 edit in the last 30 days
Last edited: 24 Oct 2026

Last edited: 24 Oct 2026

Print/export

Printable version

In other projects

Wikidata item

From Wikipedia, the free encyclopedia

ARPANET encryption devices
Security tools used on ARPANET

The ARPANET pioneered the creation of novel encryption devices for packet networks in the 1970s and 1980s, and as such were ancestors to today's IPsec architecture, and High Assurance Internet Protocol Encryptor (HAIPE) devices more specifically.

The first such device for the ARPANET was the private line Interface (PLI), and a series of additional devices was created during the 1970s and 1980s in ARPANET-related research and development, such as:¹²

Private line interface (PLI)
Black-crypto-red (BCR)
Blacker
Internet private line interface (IPLI)

Private Line Interface (PLI)

The Private Line Interface (PLI) was the first packet encryptor, sponsored by the Advanced Research Projects Agency and implemented by BBN Technologies as part of the creation of the ARPANET. It was in an early ideation phase by 1973,³ with a stated goal of providing users with the equivalent of a private, leased line through the ARPANET. In that early phase, the PLI was envisioned to provide two distinct capabilities: transferring a continuous bit steam over the ARPANET, and possibly encrypting the bit stream while it was within the ARPANET.

As design progressed, it evolved into a packet encryption device, which was approved starting in 1975 by the National Security Agency for limited deployment on the ARPANET, to protect classified data as it passed through the network.² Each PLI device incorporated a KG-34 encryption device, and as a result was a manually keyed system.⁴

Black-Crypto-Red (BCR)

Black-Crypto-Red (BCR) was an experimental, end-to-end, network packet encryption system developed in a working prototype form by BBN and the Collins Radio division of Rockwell between 1975 and 1980. BCR was the first network security system to support TCP/IP traffic for IPv3, and it incorporated the first Data Encryption Standard (DES) chips that were validated by the U.S. National Bureau of Standards (now called NIST).⁵ It provided automated, key distribution center based key management and access control (as later adopted by Kerberos and Blacker),² and supported IP header bypass.⁶

Blacker

The first Blacker program began in the late 1970s, with a follow-on eventually producing fielded devices in the late 1980s.⁷ It was sponsored by the National Security Agency as a very high assurance (A1), multi-level security system, and developed by System Development Corporation (SDC) (software) and Burroughs (hardware), and after their merger, by the resultant company Unisys.²

Internet Private Line Interface (IPLI)

The Internet Private Line Interface (IPLI) was created by BBN as a successor to the PLI. It was updated to use TCP/IP (IPv4) and newer COMSEC technology (KG-84), but still manually keyed.² They were intended for use in the Defense Data Network and also in DARPA Low-Cost Packet Radios in the SURAN project.

References

1"Edge Cryptography and the Codevelopment of Computer Networks and Cybersecurity", by Quinn DuPont, Bradley Fidler, IEEE Annals of Computing, vol. 38, Oct.-Dec. 2016, pages 55-73.
2"Re: Network Layer Encryption History and Prior Art", email by Steve Kent on the ipsec mailing list, Wed, 19 Jun 1996 10:59:39 +0100
3"Interface Messages Processors for the ARPA Network", Quarterly Technical Report No. 2, by Frank E. Heart, BBN Report 2580, BBN Technologies, pages 10-13.
4"Interface a Private Line Interface (PLI) to an IMP and a Host to a PLI", in Specifications for the Interconnection of a Host and an IMP, BBN Report No. 1822, Appendix H, January 1976.
5Internet Security Glossary, Version 2, RFC 4949, August 2007.
6Trust in Cyberspace, National Academies Press, 1999, page 301.
7DARPA Technical Accomplishments: An Historical Review of DARPA Projects Archived 2021-04-01 at the Wayback Machine, vol. 1, by Sidney G. Reed, Richard H. Van Atta, and Seymore J. Deitchman, IDA Paper P-2192, 1990, pages 20-18 to 20-20.

Study aids for ARPANET encryption devices

Terminology

ARPANET: The ARPANET pioneered the creation of novel encryption devices for packet networks in the 1970s and 1980s, and as such were ancestors to today's IPsec architecture, and High Assurance Internet Protocol Encryptor (HAIPE) devices more specifically.
encryption devices: The ARPANET pioneered the creation of novel encryption devices for packet networks in the 1970s and 1980s, and as such were ancestors to today's IPsec architecture, and High Assurance Internet Protocol Encryptor (HAIPE) devices more specifically.

Terms the article defines in bold, quoted in context.

Recent changes

21 revisions in total · 16 contributors · +4 / 0 bytes across 1 edits by 1 contributor in the last 30 days

24 Oct 2026, 20:02 UTCLovelyauth§ growthexperiments-addlink-summary-summary:1|0|0+4diff
4 Jan 2026, 10:33 UTCTemporary accountIntroduce abbreviation before using it.+33diff
21 Jul 2025, 09:05 UTCInternetArchiveBotRescuing 1 sources and tagging 0 as dead.) #IABot (v2.0.9.5+134diff
8 Apr 2025, 22:33 UTCBarrelProofWe should be describing the devices, not promoting and describing a particular article about them.−173diff
13 Mar 2025, 02:25 UTCRaync§ Blacker added link for context+35diff
13 Sept 2024, 05:54 UTCAnonymous contributorUndid revision without cause 1245468743 by Velma Larkin (talk)+20diff
13 Sept 2024, 05:15 UTCVelma LarkinmrevertedUndid revision 1245468352 by 47.157.95.50 (talk)−20diff
13 Sept 2024, 05:11 UTCAnonymous contributorreverted§ Black-Crypto-Red (BCR) unnecessary acronym+20diff

View full revision history

Rabbit hole

Where ARPANET encryption devices leads. Every connection below has a source: a link in this article, a shared Wikipedia category, or CirrusSearch text similarity. Articles already on your trail are left out.

Go deeper: linked from this article

Linked from the introduction
ARPANET
Early packet switching network (1969–1990)
The Advanced Research Projects Agency Network (ARPANET) was the first wide-area packet-switched network with distributed control and one of the first computer networks to implement the TCP/IP protocol suite.
35 min readGo deeper
Linked from the introduction
Encryption
Process of converting plaintext to ciphertext
In cryptography, encryption is the process of transforming information in a way that, ideally, only authorized parties can decode.
15 min readGo deeper
Linked from the introduction
IPsec
Secure network protocol suite
In computing, Internet Protocol Security (IPsec) is a secure network protocol suite that authenticates and encrypts packets of data to provide secure encrypted communication between two computers over an Internet Protocol network.
18 min readGo deeper
Linked from the introduction
High Assurance Internet Protocol Encryptor
Encryption device
A High Assurance Internet Protocol Encryptor (HAIPE) is a Type 1 encryption device that complies with the National Security Agency's HAIPE IS (formerly the HAIPIS, the High Assurance Internet Protocol Interoperability Specification).
3 min readGo deeper

Adjacent: shared categories and similar text

Linked in “Black-Crypto-Red (BCR)”
Data Encryption Standard
Early unclassified symmetric-key block cipher
The Data Encryption Standard (DES) is a symmetric-key algorithm for the encryption of digital data.
21 min readGo deeper
Linked in “Private Line Interface (PLI)”
DARPA
Technology research and development agency of the U.S. Department of Defense
The Defense Advanced Research Projects Agency (DARPA) is a research and development agency of the United States Department of Defense responsible for the development of emerging technologies for use by the military.
55 min readGo deeper
Linked in “Black-Crypto-Red (BCR)”
Rockwell International
American manufacturing conglomerate (1919–2001)
Rockwell International was a major American manufacturing conglomerate.
10 min readGo deeper
Linked in “Black-Crypto-Red (BCR)”
Kerberos (protocol)
Computer authentication protocol
Kerberos is a computer-network authentication protocol that works on the basis of tickets to allow nodes communicating over a non-secure network to prove their identity to one another in a secure manner.
10 min readGo deeper
Linked in “Black-Crypto-Red (BCR)”
Internet protocol suite
Framework for communication protocols used in IP networking
The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the communication protocols used in the Internet and similar computer networks according to functional criteria.
23 min readGo deeper
Linked in “Black-Crypto-Red (BCR)”
Key management
Management of cryptographic keys
Key management is the management of cryptographic keys in a cryptosystem.
12 min readGo deeper
Linked in “Private Line Interface (PLI)”
National Security Agency
U.S. signals intelligence organization
The National Security Agency (NSA) is an intelligence agency of the United States Department of Defense, under the authority of the director of national intelligence (DNI).
98 min readGo deeper
Linked in “Internet Private Line Interface (IPLI)”
Defense Data Network
The Defense Data Network (DDN) was a computer networking effort of the United States Department of Defense from 1983 through 1995. It was based on ARPANET technology.
2 min readGo deeper
Linked in “Blacker”
System Development Corporation
Computer software company based in Santa Monica, California, founded in 1955
System Development Corporation (SDC) was a computer software company based in Santa Monica, California.
3 min readGo deeper
Linked in “Private Line Interface (PLI)”
RTX BBN Technologies
American research and development company
RTX BBN Technologies (commonly BBN, from its original name of Bolt, Beranek and Newman) is an American research and development company based in Cambridge, Massachusetts.
12 min readGo deeper