Len Sassaman and Satoshi: a Cypherpunk History

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Losing Satoshi

By all accounts, Len was on track to be one of the most important cryptographers of his time. But on July 3rd, 2011, he tragically took his own life at 31, following a long battle with depression and functional neurological disorders.



Early in his career, Len distinguished himself as an authority in public-key cryptography — the foundation of Bitcoin. By 22, he was presenting at conferences and had founded a public key crypto startup with famous open-source activist Bruce Perens.

Hal Finney


Len and Finney shared one very rare and relevant skillset: they both were developers of the remailer technology that was a precursor to Bitcoin.

Diagram of a Type II Remailer
  • In 1994, Finney proposed that remailers could be monetized via anonymous “coinsand “cash tokens”.
  • Smart contracts were first discussed in the context of preventing remailer abuse. Nick Szabo’s prescient 1997 paper on smart contracts specifically references Mixmaster.
  • Ian Goldberg and Ryan Lackey (both of whom Len knew) were major figures in the remailer community who worked on an unfinished cryptocurrency called HINDE in 1998. Ian later created several early ecash clients and Ryan went on to become CSO of Tezos.

Adam Back

Crossing paths with Len in the small remailer community was Blockstream CEO Adam Back — the first person to communicate with Satoshi.

Bram Cohen’s response to this article, suggesting he and Hal Finney could have pseudonymously collaborated

Chaum & COSIC

After high school, Len worked to support his family and never had the chance to attend college. In spite of this, in 2004 he secured his “dream job” as a researcher and Ph.D. candidate at COSIC, the Computer Security and Industrial Cryptography Research Group of K.U. Leuven in Belgium.

  • The invention of cryptocurrency in his 1983 paper Blind Signatures for Untraceable Payments.
  • The invention of the blockchain, with his 1982 dissertation including code for all but one element of the blockchain detailed in the Bitcoin whitepaper.
  • The creation of the first electronic cash system with his company Digicash. Anonymous payment between digital pseudonyms was central to this vision.

Len’s Research

Len worked at COSIC in Belgium until his death in 2011. In that time, he accumulated an impressive 45 publications and 20 conference committee positions.

Pynchon Gate and meta-index + bucket pool architecture
Diagram of the Byzantine Fault

Satoshi as Academic

Numerous clues suggest that Satoshi was working in academia during Bitcoin’s development, an idea embraced by Bitcoin Foundation founder Gavin Andersen.

Satoshi in Europe

Since COSIC was based in Leuven, Len was living in Belgium during Bitcoin’s development. This is salient given that a number of facts suggest that Satoshi was based in Europe — the primary focus of an early inquiry by The New Yorker.

P2P Networking

While not the first cryptocurrency, Bitcoin was the first to be based on a fully P2P, distributed network. The importance of this is emphasized in Satoshi’s very first reference to Bitcoin:

Bram and Len in an interview about CodeCon
Bittorent’s design compared to Napster
Screenshot of the Mnet client
“Zooko’s triangle is a trilemma of three properties that are generally considered desirable for names of participants in a network protocol”


Even by the standards of the Cypherpunk community, both Len and Satoshi had especially strong ideological convictions and commitments to open knowledge.

In response to this story, Bram stated that Len had a predilection for anonymous releases


Just as Satoshi created Bitcoin from behind a pseudonym, Len was in a sense forced to live behind a persona of his own. Following an incident in 2006, Len suffered from increasingly severe non-epileptic seizures and functional neurological problems, which served to exacerbate the depression he had battled since youth.

Len presenting at Dartmouth shortly before his death



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