Satoshi Files: Adam Back
Crypto Basics

Satoshi Files: Adam Back

Created 5mo ago, last updated 5mo ago

Adam Back is a respected and experienced cryptographer who was an early innovator in the blockchain space.

Satoshi Files: Adam Back

Table of Contents

Adam Back has worked extensively on cryptocurrency and other privacy-oriented technologies. He has also written a lot of books and academic papers, including ones about cryptographic protocols, electronic signatures and electronic currency systems.

He is now the chief executive officer of Blockstream, a blockchain technology company that provides solutions for the safekeeping and exchange of digital assets. He also regularly speaks at conventions and seminars pertaining to the field.


Join us in showcasing the cryptocurrency revolution, one newsletter at a time. Subscribe now to get daily news and market updates right to your inbox, along with our millions of other subscribers (that’s right, millions love us!) — what are you waiting for?

Early Life

Back spent his formative years in London, where he developed an early love for technology. In his spare time, he reverse-engineered video games and found decryption keys in some early software while teaching himself BASIC coding on a Sinclair ZX81.

Like most other cryptographers, Back studied computer science at both the undergraduate and graduate levels. His first major cryptographic contribution, the Hashcash proof-of-work system, emerged in the late 1990s. He shared his invention with a group of radical, online cryptographers called the Cypherpunks.


The Cypherpunks are a community of cryptography experts who meet online to debate and exchange cutting-edge research and developments in the field. The group includes not just Back, but also Hal Finney, who developed Reusable Proof-of-Work, or RPoW; David Chaum, the "godfather of cryptography,” whose contributions include the first digital money — Ecash; and Satoshi Nakamoto, Bitcoin’s creator. Adam Back's Hashcash protocol was crucial to the success of several of the group's innovations, including Finney's RPoW and Satoshi's Bitcoin.

Hashcash Proof-of-Work

A Hashcash stamp in the header, which verifies the sender spent a minimum amount of processing power during the email's creation and transmission, can be used to limit spam and denial-of-service attacks. Filters for incoming emails can tell which ones were created and sent to ten million people at once and are therefore spam, and which ones utilized a fair amount of CPU power and are therefore valid.

Back’s Hashcash couldn’t have arrived at a better moment. Though email was widely used by the late 1980s and 1990s, spam messages were a serious issue at the time. The vast majority of the alternative solutions presented involved some form of micropayment, in which email senders would be charged a small amount of money for each email they sent. This would have resulted in spammers having to pay thousands of dollars to send their emails, but would have prevented people in developing countries from using email.

However, Hashcash provided an elegant solution to this issue that sidestepped the logistical, ethical, and moral complications that arise with charging users to send and receive email.

Cited in the Bitcoin Whitepaper

Unexpectedly, Hashcash became an important part of Bitcoin's topology. Satoshi Nakamoto, in his 2008 whitepaper on Bitcoin, cites Adam Back's Hashcash as an influence on Bitcoin's decentralized timestamp server.

“To implement a distributed timestamp server on a peer-to-peer basis, we will need to use a proof-of-work system similar to Adam Back’s Hashcash.”
As Satoshi finished drafting the Bitcoin whitepaper, he contacted Back, who led him to his fellow Cypherpunk and cryptographer Wei Dai. Dai’s b-money was referenced in the final draft of the whitepaper thanks to Back.
Years later, when Back was being interviewed about Bitcoin and Satoshi, he was asked whether he knew who Satoshi was. He said no. And when reporters asked for the emails between him and Satoshi, he said if he found any, he would delete or shred them. He also told Bloomberg in 2020 that he’s not Satoshi.

Bitcoin's implementation of Hashcash is a bit different from that of email servers. Bitcoin miners gather unconfirmed transactions into blocks, which are then only added to the network if the hash is difficult enough. To put it another way, miners try to guess by brute force an arbitrary number using computer power: if enough power is used, the block will be added to the chain since its hash will have met the network's difficulty criteria.

Thanks to his Hashcash invention, many people regard Adam Back as one of the founding fathers of contemporary cryptography, alongside David Chaum (who developed the first digital money, Ecash), and Tim May (who developed the theory of Crypto Anarchy).

Pretty Good Privacy (PGP)

Like many other Cypherpunks, Back is very concerned about the ways in which governments restrict the privacy rights of their subjects, particularly in the digital sphere. Phil Zimmerman, a contemporary of Back's in the field of cryptography, published a paper in 1991 titled "Pretty Good Privacy" that made the first publicly available public-key cryptography available to the public. The PGP code was disseminated globally through the internet.

Unfortunately for Zimmerman (and many other cryptographers, including Back), an archaic US law meant cryptography could be treated as a type of munition. As a result, the United States Customs and Border Protection opened a criminal inquiry into whether or not Zimmerman and his associates broke the Weapons Export Control Act by releasing the PGP encryption code.

Back and his fellow Cypherpunks were outraged. They decided to draw attention to the absurdity of the inquiry by printing "illegal" code on T-shirts and adding the warning:
“This shirt is classified as a munition and may not be exported from the United States or shown to foreign nationals.”

After a positive judgment in a similar case (Bernstein v. United States) the inquiry was abandoned. Based on First Amendment concerns, the judge ruled that the United States government cannot prohibit the release of software source code or cryptographic code.

After the decision, MIT released the PGP code, and Zimmerman founded PGP Inc. to continue its development.

With his invention of the Hashcash algorithm, Back has been in high demand as a network security architect and a cryptography consultant. He started the company Blockstream in 2014, which uses the Bitcoin blockchain to create products and networks for the financial sector. He's been serving as the company’s CEO since 2016.

Crossing Paths With Craig Wright

Back isn't the type of person who actively seeks out drama and confrontation, but in 2019, it found him anyway. He was sued for defamation of character by Australian businessman Craig Wright, who claims to be Satoshi Nakamoto. At the time, Wright was in the middle of a legal battle with a relative of his late business partner, David Kleiman. Wright, according to Back, lacked technical proof to prove he was Satoshi.

“From a tech perspective it is clear neither CSW nor Kleinman are Satoshi.”
In a follow-up, he said that Wright’s argument relied on fabricated evidence.
“Does that mean suppress comments from the large ecosystem in observing the fellow standing next to you has published fake "proofs" with falsified digital sigs, existential forgeries, and is subject of at least 2 court cases for alleged doc forgery & tax fraud?”
Wright’s media team at Coin Geek published a vitriolic rebuttal. They declared Wright was prepared to sue Back in an attempt to get an apology from him. “Back merely has to retract his statements, not make them again, apologize and acknowledge the statements were false,” they wrote. “If Back doesn’t comply, Wright will be happy to take him to court.”
“Wright is ready to stand up in court and prove that he’s Satoshi, and he dares his detractors to be adults about the whole thing and face him in a court of law,” they added. “It might prove to be an ugly affair, but it’s the fairest way to end this mess once and for all.”
In the end, however, no case ever made it to trial. Although Wright did indeed file suit, he conceded the case before it ever reached a court, and he had to pay Back’s legal fees for the trouble.

Evidence That Adam Back Could Be Satoshi Nakamoto

#1 His Knowledge and Credentials

Not only does Back have a Ph.D. in computer science and a history of studying cryptography in academia, but he has also built his whole career on ideas that are central to Bitcoin.

#2 He Was a Cypherpunk

Adam Back was a pioneer in the field of cryptography, and his contributions to the Cypherpunk movement were very important. He was an active participant in the group's debates, and his Hashcash function inspired the development of other algorithms and programmes by his fellow Cypherpunks, such as Hal Finney's RPoW and Bitcoin.

#3 He Invented the Hashcash Function

The Hashcash function, which Back developed, was important in Satoshi's creation of Bitcoin and is often seen as Back's crowning cryptographic achievement.

#4 He Was There When Bitcoin Started

Back was the second person Satoshi reached out to with the earliest draft of the Bitcoin whitepaper.

Although the emails between him and Satoshi aren’t public, and Back said he would destroy or shred them if he found them, it’s important to remember how close he was to Bitcoin when it launched.

Evidence That Adam Back Likely Isn’t Satoshi Nakamoto

#1 He Denies Being Satoshi

In an interview with Bloomberg in 2020, Back flat-out denied any involvement in the creation of Bitcoin.

#2 A Lack of Direct Evidence Pointing To Him.

There is scant concrete evidence that suggests Back is in fact Satoshi. The vast majority of it is circumstantial or has to do with his credentials.

So, do you think Adam Back created Bitcoin?

This article contains links to third-party websites or other content for information purposes only (“Third-Party Sites”). The Third-Party Sites are not under the control of CoinMarketCap, and CoinMarketCap is not responsible for the content of any Third-Party Site, including without limitation any link contained in a Third-Party Site, or any changes or updates to a Third-Party Site. CoinMarketCap is providing these links to you only as a convenience, and the inclusion of any link does not imply endorsement, approval or recommendation by CoinMarketCap of the site or any association with its operators. This article is intended to be used and must be used for informational purposes only. It is important to do your own research and analysis before making any material decisions related to any of the products or services described. This article is not intended as, and shall not be construed as, financial advice. The views and opinions expressed in this article are the author’s [company’s] own and do not necessarily reflect those of CoinMarketCap.
0 people liked this article