Len Sassaman

Introduction

Leonard Harris Sassaman (April 9, 1980–July 3, 2011) was a prominent figure in the field of computer security and privacy. He was an OG cypherpunk, PhD student, entrepreneur, and startup founder. Sassaman contributed to projects like the Mixmaster anonymous remailer, and involved in the development of technologies that enhance user privacy online. He was also an advocate for digital rights and privacy issues.

He was pursuing a PhD at the Katholieke Universiteit Leuven in Belgium, and known for his work on cryptography, particularly in relation to anonymous communication systems. He was a researcher with the Computer Security and Industrial Cryptography (COSIC) research group, led by Bart Preneel. David Chaum and Bart Preneel were his advisors.

Fact matrix

Detail	Value	Notes
Full name	Leonard Harris Sassaman
Birth date	9 April 1980
Birthplace	Pottstown, Pennsylvania, USA
Family: parents	Jim and Dana Hartshorn	(from Bitcoin tribute)
Family: siblings	Calvin	(from Bitcoin tribute)
Family: spouse	Meredith L. Patterson	m. 2006
Family: children
Education	Katholieke Universiteit Leuven
Fields	Computer science, anonymous remailers
Employment	COSIC, Network Associates, KnownSafe, Inc.
Affiliations	Cypherpunks mailing list, Shmoo Group
Residence	Leuven, Belgium
Website
Social	Twitter	ICQ:10735603, LiveJournal

English usage and writing quirks

Research interests and publications

Privacy was a key theme in Sassaman’s research:

My research is centered around the topic of privacy enhancing technologies. In particular, I am focused on both attacking and defending anonymous communication systems, exploring the applicability of information-theoretic secure systems for privacy solutions, and designing protocols which satisfy the specific needs of the use case for which they are applied. I have a very strong interest in the real-world applicability of my work; while some of what I do is pure theory, I have always held the believe that if a system cannot be implemented easily or be easily understood by the implementors, its utility is limited. Similarly, I believe that usability is a security concern; systems that do not pay close attention to the human interaction factors involved risk failing to provide security by failing to attract users. Thus, I follow closely the fields of HCI and Applied Programming as well as Information Theory, Cryptography, and Anonymity.

Publications

Publications authored or co-authored by Sassaman:

2011

M. L. Patterson, and L. Sassaman, “Towards a Theory of Computer Insecurity: a Formal Language-Theoretic Approach,” Dartmouth College Institute for Security, Technology, and Society Speaker Series, Hanover, NH, USA, 2011.

2010

L. Sassaman, “Minimizing Attack Surfaces with Language-Theoretic Security,” EIDMA/DIAMANT Cryptography Working Group, Utrecht, NL, 2010.
J. C. Anderson, L. Sassaman, and E. You, “The rise of Distributed, Decentralized, Amateur/Citizen Science and Do It Yourself Biology: Safety and Security Concerns,” Open Science Summit 2010, Berkeley, CA, USA, 2010.
M. L. Patterson, and L. Sassaman, “Exploiting the Forest with Trees,” Black Hat Briefings, Las Vegas, NV, USA, 2010.
M. L. Patterson, and L. Sassaman, “Exploiting Computational Slack in Protocol Grammars,” PH-Neutral, Berlin, DE, 2010.
L. Sassaman, “Language Theoretic Security Attacks: Exploiting Computational Slack in Protocol Grammars,” COSIC Seminar, Leuven, BE, 2010.
L. Sassaman, “Ethical Guidelines for Computer Security Researchers: “Be Reasonable”,” In Workshop on Ethics in Computer Security Research 2010, Lecture Notes in Computer Science, Springer-Verlag, 6 pages, 2010.
L. F. Cranor, E. Kenneally, and L. Sassaman, “Towards a Code of Ethics for Computer Security Research,” Workshop on Ethics in Computer Security Research (WECSR 2010), Tenerife, ES, 2010.
D. Kaminsky, M. L. Patterson, and L. Sassaman, “PKI Layer Cake: New Collision Attacks Against the Global X.509 Infrastructure,” In Financial Cryptography and Data Security - Fourteenth International Conference, FC 2010, Lecture Notes in Computer Science 6052, R. Sion (ed.), Springer-Verlag, 16 pages, 2010.

2009

L. Sassaman, “Lessons in Vulnerability Disclosure: So You Broke The Internet -- What Now?,” COSIC Seminar, Leuven, BE, 2009.
D. Kaminsky, and L. Sassaman, “Breaking Web Security: Practical Attacks on X.509,” Black Hat Briefings, Las Vegas, NV, USA, 2009.

2008

G. Danezis, and L. Sassaman, “How to Bypass Two Anonymity Revocation Schemes,” In Privacy Enhancing Technologies - Eighth International Symposium, PETS 2008, Lecture Notes in Computer Science 5134, N. Borisov, and I. Goldberg (eds.), Springer-Verlag, pp. 187-201, 2008.
L. Sassaman, and B. Preneel, “The Byzantine Postman Problem,” In Proceedings of the Twenty-Ninth Symposium on Information Theory in the Benelux, Werkgemeenschap voor Informatie- en Communicatietheorie, pp. 129-135, 2008.
L. Sassaman, “A Review of the OLPC XO Security Model,” Stanford University Security Seminar, Stanford, CA, USA, 2008.
M. L. Patterson, L. Sassaman, and D. Chaum, “Freezing More Than Bits: Chilling Effects of the OLPC XO Security Model,” In Usability, Psychology, and Security 2008, E. Churchill, and R. Dhamija (eds.), USENIX, pp. 5:1-5:5, 2008.
L. Sassaman, “Freezing More Than Bits: Chilling Effects of the OLPC XO Security Model,” University of California, Berkeley Security Reading Group, Berkeley, CA, USA, 2008.
L. Sassaman, “Toward an Information-Theoretically Secure Anonymous Communication Service,” Master thesis, Katholieke Universiteit Leuven, B. Preneel (promotor), 94 pages, 2008.

2007

L. Sassaman, “Anonymity for 2015,” Twenty-Fourth Chaos Communication Congress, Berlin, DE, 2007.
L. Sassaman, “Anonymity and its Discontents,” Black Hat Briefings, Las Vegas, NV, USA, 2007.
L. Sassaman, and B. Preneel, “Solving the Byzantine Postman Problem,” Technical Report ESAT-COSIC 2007-004, 15 pages, 2007.
K Kursawe, P. Palfrader, and L. Sassaman, “Echolot and Leuchtfeuer: Measuring the Reliability of Unreliable Mixes,” Technical Report ESAT-COSIC 2007-005, 15 pages, 2007.
M. L. Patterson, and L. Sassaman, “Subliminal Channels in the Private Information Retrieval Protocols,” In Proceedings of the Twenty-Eighth Symposium on Information Theory in the Benelux, Werkgemeenschap voor Informatie- en Communicatietheorie, 8 pages, 2007.
L. Sassaman, “The Faithless Endpoint: How Tor puts certain users at greater risk,” Technical Report ESAT-COSIC 2007-003, pp. 1-4, 2007.
L. Sassaman, and B. Preneel, “The Byzantine Postman Problem: A Trivial Attack against PIR-based Nym Servers,” Technical Report ESAT-COSIC 2007-001, pp. 1-7, 2007.

2005

L. Sassaman, B. Cohen, and N. Mathewson, “The Pynchon Gate: A Secure Method of Pseudonymous Mail Retrieval,” In Proceedings of the Fourth ACM workshop on Privacy in the electronic society (WPES 2005), S. De Capitani di Vimercati, and R. Dingledine (eds.), ACM, pp. 1-9, 2005.
R. Dingledine, P. Palfrader, and L. Sassaman, “Panel: Future Anonymity Systems,” What The Hack, Liempde, NL, 2005.

2004

L. Sassaman, “Privacy Issues in Identity Management,” Thirteenth CACR Information Security Workshop & Fifth Annual Privacy and Security Workshop, Toronto, ON, CA, 2004.
L. Sassaman, “Making Privacy Enhancing Technology a Reality,” TOORCON, San Diego, CA, USA, 2004.
C. Diaz, L. Sassaman, and E. Dewitte, “Comparison between two practical mix designs,” In Ninth European Symposium on Research in Computer Security (ESORICS 2004), Lecture Notes in Computer Science 3193, D. Gollmann, P. Ryan, and P. Samarati (eds.), Springer-Verlag, pp. 141-159, 2004.
L. Sassaman, “The Anonymity Toolkit,” Black Hat Briefings, Las Vegas, NV, USA, 2004.
L. Sassaman, “Ten Years of Practical Anonymity,” The Fifth HOPE Conference, New York, NY, USA, 2004.

2003

L. Sassaman, and C. Wysopal, “Panel: How can Independent Researchers be adequately compensated for the valuable service they provide to vendors and customers while encouraging responsible reporting?,” CyberSecurity, Research & Disclosure, Stanford, CA, USA, 2003.
G. Danezis, and L. Sassaman, “Heartbeat Traffic to Counter $(n-1)$ Attacks: Red-Green-Black Mixes,” In Proceedings of the Second ACM workshop on Privacy in the electronic society (WPES 2003) ACM 101039, P. Samarati, and P. F. Syverson (eds.), ACM, pp. 89-93, 2003.
R. Lackey, P. Palfrader, and L. Sassaman, “Behind the Remailers: The Operators and Developers of Anonymity Services,” DEFCON 11, Las Vegas, NV, USA, 2003.
R. Dingledine, and L. Sassaman, “Attacks on Anonymity Systems: Theory and Practice,” Black Hat Briefings, Las Vegas, NV, USA, 2003.
L. Sassaman, “Designing Useful Privacy Applications,” Black Hat Europe Briefings 2003, Amsterdam, NL, 2003.
L. Sassaman, “Anonymity in Practice,” COSIC Seminar, Leuven, BE, 2003.
L. Sassaman, “Introduction to Anonymity Techniques,” University of Cambridge Security Seminar, Cambridge, UK, 2003.
S. Kopsell, L. Sassaman, and A. Shostack, “Panel: Experiences Deploying Anonymous Communication Systems,” Workshop on Privacy Enhancing Technologies 2003, Dresden, DE, 2003.

2002

L. Sassaman, “The Promise of Privacy,” Sixteenth Conference on Systems Administration (LISA 2002), Philadelphia, PA, USA, 2002.
L. Sassaman, “Anonymity Services and The Law,” DEFCON 10, Las Vegas, NV, USA, 2002.
L. Sassaman, “Forensic Dead-Ends: Tracing Users Through Anonymous Remailers,” Black Hat Briefings, Las Vegas, NV, USA, 2002.
L. Sassaman, “BOF: Future Directions for Anonymous Remailers,” Computers, Freedom, and Privacy, San Francisco, CA, USA, 2002.

2001

L. Sassaman, “Fundamental Flaws in the SSL Certificate Authority Model,” DEFCON 9, Las Vegas, NV, USA, 2001. 2000
L. Sassaman, “The State of the OpenPGP Keyserver Infrastructure,” North American Network Operators Group, Twentieth Conference, Washington, DC, USA, 2000.

Affiliated projects

Lead developer of FreeCert
Assisted with Bastille Linux
Assisted with GnuPG
Assisted with PGP Public Key Server
Assisted with micq
Assisted with echolot
Assisted with Mixminion
Lead developer of Mixmaster
Assisted with CryptNET: Public Key Server

Known aliases and handles

rabbi was Sassaman’s most commonly known and used handle.
Sion used in Multi-User Dungeon (MUD) online games
SIrabbi used on the Advogato website. Advogato is a Portuguese word meaning Lawyer and the website description read: “A network of technically sophisticated spies working together to bring freedom and democracy to China and America.”

Quickie.Net

This was a shared server situation hosting many subdomains and user homes.

Early website: http://quickie.net (offline)
Early website: http://sion.quickie.net (offline)
Early email: lhs@quickie.net
Early email: rabbi@quickie.net
Early email: sysadmin@quickie.net

Oddly, Wayback Machine scans of the same IP on November 30, 2001 show a different website about gaming titled GAME and WEB HOSTINGS : TVO PRODUCTIONS with the following footer content:

Best viewed with Microsoft Internet Explorer over Netscape at 800 x 400 and not 1024 x 768 pixels
TVO PRODUCTIONS © 2001 since 1997 / v2.3 / / tho@thovo.com

Perhaps this is explainable by Quickie.Net taking over a recently active IP address, but whatever the case, the next scan to occur on January 21, 2002 reveals the Quickie.Net page content:

Quickie.Net

Site under construction, offline until further notice.

If you are looking for the homepage of L. Sassaman , follow this link.
For Andrew Schaefer follow that.
For Sankin, go here.
And for Mycroft, go there.

Academic

Email: len.sassaman@esat.kuleuven.be
User space: https://securehomes.esat.kuleuven.be/~lsassama/ (offline)

Anonymizer

Email: rabbi@anonymizer.com

Crypto Rights

Email: rabbi@cryptorights.org

DEOR-SOI MUD

Email: len@deor.org (“I can be reached at len at deor dot org.”)
- This email address appears in the Adobe database breach.
Email: rabbi@deor.org

INetU

(www.inetu.net)

An Allentown, Pennsylvania based managed hosting company

Email: lhs@inetu.net

Melon Traffickers

Website: http://www.melontraffickers.com (offline)
Email: rabbi@melontraffickers.com

Network Associates Inc.

Email: Len_Sassaman@nai.com

Nomen Abditum Services

(“Hidden Name Services”)

Website: http://www.abditum.com (offline)
User space: http://www.abditum.com/~rabbi (offline)
Email: rabbi@abditum.com
- Appears in Evite breach data
- Appears in 2021 IntelX paste scrape data
- Appears in LiveJournal breach data
- Appears in Verifications IO breach data

PGP

Email: len@pgp.com

Talon

Email: lhs@talon.net
Email: rabbi@talon.net

Unconundrum

Email: LSassaman@unconundrum.com

PGP public keys

uid	fingerprint	key	packets
L. Sassaman (Archival Key – not for email use)	566b5ca8a73334aaa482586f38d9dba83af92bd0	key	packets
L. Sassaman rabbi@quickie.net	ba48e94bfc3c6ed6e5458e299fdd29eef05144c9	key	packets
L. Sassaman rabbi@quickie.net	7a1a407fb1ca7e4eae85e7303d8af1b209ac0a6a	key	packets
L. Sassaman len@pgp.com

Forums and mailing lists

Some of the forums and mailing lists that Sassaman participated in or subscribed to:

Bugtraq Unix
Cypherpunks
FreeBSD Hackers
FreeBSD Ports
FreeBSD Ports Bugs
OpenSSL Dev
OpenSSL Users

Usenet

List of some newsgroups that Sassaman participated in:

alt.bored
alt.celebrities
alt.clearing.technology
alt.cotse
alt.privacy
alt.security.pgp
alt.troll
alt.tv.millennium
mpc.lists.freebsd.questions

Bitcoin onchain testimonial

Dan Kaminsky presented at Black Hat USA 2011, and shared a testimonial to Sassaman written to the Bitcoin blockchain in block 138725 with transaction hash 930a2114cdaa86e1fac46d15c74e81c09eee1d4150ff9d48e76cb0697d8e1d72:

---BEGIN TRIBUTE---
#./BitLen
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=-=-=-=-=-=-=-=-=-=
LEN "rabbi" SASSAMA
     1980-2011
Len was our friend.
A brilliant mind,
a kind soul, and
a devious schemer;
husband to Meredith
brother to Calvin,
son to Jim and
Dana Hartshorn,
coauthor and
cofounder and
Shmoo and so much
more.  We dedicate
this silly hack to
Len, who would have
found it absolutely
hilarious.
--Dan Kaminsky,
Travis Goodspeed
P.S.  My apologies,
BitCoin people.  He
also would have
LOL'd at BitCoin's
new dependency upon
   ASCII BERNANKE
:'::.:::::.:::.::.:
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----END TRIBUTE----

Related: Len Sassaman Project

Lectures and talks

Towards a formal theory of computer insecurity: a language-theoretic approach

Articles of note

Articles and research about Sassaman as Nakamoto:

Interesting coincidences

SNNO minted by obxium in 2022 on a custom Ethereum ERC-1155 contract restricted to one token.

SASSAMAN and NAKAMOTO are strings of the same length, and have a similar word shape in both morphological structure and phonological form.
Sassaman worked on PGP at Network Associates with Hal Finney.
Both Sassaman and Nakamoto have repeatedly used instances of British English in their writing.

Bram Cohen tweets

“Also I have a vague memory - mostly because Len told me about it and I wasn’t paying close attention - that there was a nym called Product Cipher which pseudonymously posted the first ring signatures implementation to cypherpunks and then disappeared.”

Source

“The implication with that one seemed to be that it was Hal or Len or some combination of the two, very unsure though, and don’t know if it got clarified later.”

Source

“Len also tried to get me to publish BitTorrent pseudonymously which seems indicative of something”

Source

The case against

A few points which cast doubt on the possibility that Sassaman was Nakamoto do exist.

Meredith Patterson

Len Sassaman’s widow Meredith Patterson doesn’t think Sassaman was Nakamoto. Commenting on the article Len Sassaman and Satoshi: a Cypherpunk History published by Evan Hatch in 2021, she Tweeted:

“It’s a very well-researched and respectful article, but to the best of my knowledge, Len was not Satoshi.”

Given their close personal and professional relationship, it’s difficult to imagine that Sassaman withheld knowledge about the creation of Bitcoin from Patterson, but not impossible.

After all Bram Cohen was close friends with Sassaman, and tweeted this on March 3, 2021:

“It’s a bit emotional for me to talk about this, but I will say that Len posted pseudonymously on the cypherpunks list constantly, including at least one fleshed-out and long-lived handle, and even I didn’t know what it was”

Sassaman’s own words on Bitcoin

Sassaman spoke publicly about Bitcoin, posting dozens of Tweets on the topic, like:

“Personally I think bitcoin is overhyped, but the hype itself is interesting.”

and showing pessimism about Bitcoin learning from prior art:

“I’d be more optimistic about BitCoin if I had the impression that they were acting on lessons learned from prior attempts.”

and engaging with Zooko Wilcox, the Zcash cryptocurrency founder:

“You have the choice to avoid using Internet banking entirely. What’s the equivalent choice with bitcoin?”

His last Tweet about Bitcoin:

“… and The Economist runs a story on Bitcoin.”

Sassaman’s public words on Bitcoin undoubtedly leave the impression that he didn’t really like Bitcoin, but one can’t wonder if all this was just a ruse.

2014 P2P Foundation forum post

Since Sassaman died in 2011, some believe that he couldn’t possibly be Nakamoto, because of this lone P2P Foundation’s forum post allegedly made by Nakamoto in 2014:

From:
Satoshi Nakamoto
Subject:
Bitcoin open source implementation of P2P currency
Date:
March 7, 2014 at 01:17:00 UTC

I am not Dorian Nakamoto.

In a wild turn of events, P2P Foundation itself revealed on September 9, 2014 that the GMX email account, which Nakamoto originally used to announce Bitcoin in the P2P Foundation’s Ning forum got hacked.

This seriously calls into question the validity of the March 7, 2014 post because that email account could have reset the password to the forum account, so whomever was controlling it at the time could have posted to appear as Nakamoto.

This author doesn’t accept the 2014 post as a true communication by the entity associated with the Satoshi Nakamoto persona.