Alice and Bob: A History Of The World’s Most Famous Couple

Alice and Bob: A History Of The World’s Most Famous

Couple

Alice and Bob are the world’s most famous cryptographic couple. Since their invention

in 1978, they have at once been called “inseparable,” and have been the subject of

numerous divorces, travels, and torments. In the ensuing years, other characters have

joined their cryptographic family. There’s Eve, the passive and submissive

eavesdropper, Mallory the malicious attacker, and Trent, trusted by all, just to name a

few.

While Alice, Bob, and their extended family were originally used to explain how public

archetype of digital exchange, and a lens through which to view broader digital culture.

This website details the major events in the “lives” of Alice and Bob, from their birth in

1978 onwards. It is also the public, multimedia component for a related academic

research project by Quinn DuPont and Alana Cattapan.

Synopsis

Alice and Bob are fictional characters originally invented to make research in cryptology

easier to understand. In a now-famous paper (“A method for obtaining digital signatures

and public-key cryptosystems”), authors Ron Rivest, Adi Shamir, and Leonard

Adleman described exchanges between a sender and receiver of information as follows:

“For our scenarios we suppose that A and B (also known as Alice and Bob) are two

which also made these abstract characters visible to the world. By the 1990s, mentions

of Alice and Bob could be found in a wide range of fields—from game theory, to

quantum cryptography, to physics, to economics, and beyond. As other characters were

added, they too were given typical definitions, personalities, and life stories.

The ubiquity of Alice and Bob in the university led to winking references in digital and

popular culture, including jokes, t-shirts, music, and comics. Noting their importance, in

cryptology research if not digital culture, the security company that created Alice and

Bob, RSA Security, chose them as their theme for their 2011 annual security

conference.

The following timeline traces the major events in the “lives” of Alice and Bob, focusing

on the historical context in which they have come to be central to the research, industry,

and culture of cryptology. This timeline aims to create an accurate record of the history

of Alice and Bob, as well as to identify the cultural and gendered contexts in which they

emerged.

responsible for what was then known as “non-secret” encryption were James H. Ellis,

Clifford Cocks, and Malcolm Williamson.

In the late 1960s, searching for a solution to key management, knowing that such a

technique was critical to the new digital (and increasingly, networked) information

environments, James Ellis read a classified document on the Bell C43 Project from

1943-44, a “Type II Ciphony” device, or vocoder. This secure telephone device was

developed in after SIGSALY, developed by Bell Labs in 1941-42 and used during World

War II. Like SIGSALY, the Type II device was unusual in that its “encryption”

(technically, scrambling) was made possible by the direct involvement of the receiving

party, and without the need for pre-arranged exchange of information.

On his own admission, Ellis’ number theory was weak and so he was unable to find a

suitable method for the encryption process—a process that would require some

technique that would be easy to solve in the one direction, but hard to reverse. This task

of finding what would become known as a mathematical one-way function was left to his

colleague Clifford Cocks. So, in November 1973, Cocks published an internal report

detailing a “possible implementation” of Ellis’ non-secret encryption. Cocks’

implementation, it would later turn out, was basically a version of the 1978 RSA

algorithm. In January 1974, Malcolm Williamson published an internal report detailing

another possible implementation of Ellis’ non-secret encryption; this time, Williamson’s

algorithm was basically a version of the one later identified by Diffie and Hellman, in

their famous “New Directions” paper, which was the first unclassified description of

public-key cryptography.

Public-Key Cryptography is Re-Invented (November,

In November 1976, Whitfield “Whit” Diffie and Martin Hellman published a paper

Since Ellis, Cocks, and Williamson’s work on “non-secret” encryption was kept secret by

and SIGABA machines). This was an onerous and risky process that needed to be

repeated often (it is critical to change cryptographic keys frequently to maintain

security). This process was complicated and labour intensive, requiring trusted

personnel to transport codes on sheets of paper or electro-mechanical “fill” devices.

Even the state-of-the-art Arpanet, which later became the Internet, encrypted

communication required the careful coordination of cryptographic keys across distant

“Private Line Interfaces.” As the number of nodes in the secure network increased, so

too did the labour of exchanging keys.

Diffie and Hellman had invented, for the second time (unbeknownst to them), a way to

encrypt communication over insecure channels without the prior exchange of keys. This

communicate, to organize, and to socialize.

While Ellis, Cocks, and Williamson were inventing “non-secret” encryption at GCHQ,

Diffie had become inspired by John McCarthy’s investigation of cryptography for large