When the Cipher Fades: Len Sassaman and the Shadow That Never Appeared

The late Len Sassaman, a renowned American cryptographer and one of the earliest advocates of the cypherpunks movement, dedicated himself to the development of PGP (Pretty Good Privacy) encryption software and open-source privacy technologies. He was a doctoral student in electrical engineering at the Catholic University of Leuven in Belgium, researching P2P networks under the guidance of David Chaum, one of the inventors of several forms of cash. He was also the maintainer and main developer of the Mixmaster anonymous mail forwarder code.

(Sources: blocktempo)

According to his wife, a computer scientist, he committed suicide on July 3, 2011, at the age of 31. Bitcoin block 138,725 contains a transaction paying homage to Sassaman in ASCII art style.

I. The Rain in Leuven

It always rained in Belgium in 1999. In the computer labs of KU Leuven, 21-year-old Len Sassaman stared at flickering screens, his fingers dancing across the keyboard in a rhythm that bordered on desperation. Outside, rain traced paths down the Gothic spires like countless invisible threads.

Len still wore his shoulder-length blond hair back then, paired with faded black hoodies. His professors recalled this American exchange student as the last to leave the lab each night—“as if he were in a silent conversation with the machine.” Few knew what he was building: code that resembled encryption schemes, yet laced with odd redundancies, as if whispering secrets to an unseen recipient.

“True privacy demands absolute chaos,” he told a lone Chinese classmate one stormy evening, his blue eyes glowing unnaturally bright under the monitor’s light. The classmate later wrote in a blog that Len’s hands trembled as he spoke, as though enduring some invisible torment.

In 2001, Len joined the cypherpunk mailing list. His first post sparked immediate debate—a proposal for an anonymity network based on mixnets, ending with a poem: “Packets embrace in the dark / Like long-lost lovers / Never knowing if the other is real.”

This blend of romanticism and technical fervor would later echo in Satoshi Nakamoto’s writings.

II. The Sigh of the Mixmaster

In Berlin’s underground hacker cafes—places with steampunk copper pipes twisting overhead—Len became a fixture by 2005. He had grown gaunt, cropped his hair short, and added a silver ear stud shaped like a Bitcoin symbol, meaningless to most at the time.

“The financial system is violence,” he murmured in a corner booth to a group of young hackers, his voice barely audible over the hiss of espresso machines. “We need to build escape tunnels.” Witnesses later recalled how Len demoed a prototype encrypted payment system that night—one eerily similar to the Bitcoin whitepaper three years later.

His partner, Meredith, noted in her diary: “Len wakes at 3 a.m. in panic, then codes through the night on projects he refuses to explain. One morning, I found the study floor littered with pages of equations, a large red ‘B’ scrawled in the center.”

By spring 2008, Len’s behavior grew erratic. He deleted all social accounts yet remained hyperactive on forums under various guises. One pseudonym, linked later to early Bitcoin developer Hal Finney, bore posts in Len’s unmistakable style.

III. The Silent Key

On October 31, 2008, Satoshi Nakamoto released the Bitcoin whitepaper. That same day, Len emailed Meredith three words: “It begins. Goodbye.”

Over the next months, the cryptography world witnessed strange overlaps: whenever Satoshi faced technical challenges in forum posts, Len would publish detailed explanations elsewhere. When Satoshi vanished for weeks, colleagues confirmed Len was “in seclusion on a revolutionary project.”

Most telling was the timezone. Bitcoin forum logs showed Satoshi active during European daylight hours—while Len lived in Brussels. When pressed years later, his response was a melancholic smile: “Timezones are the easiest thing to forge.”

January 3, 2009: the Bitcoin genesis block is mined. That day, a new encrypted folder named “Genesis” appeared in Len’s repositories—requiring a 256-bit key, exactly SHA-256’s length. No one ever unlocked it.

IV. The Vanishing Hash

July 3, 2011: in their Brussels apartment, Meredith discovered Len’s body. The medical examiner timed death just hours after Satoshi’s final forum post. On the desk: a laptop with its drive physically destroyed, beside a note: “Private keys burned.”

At the funeral, cypherpunks exchanged PGP-encrypted messages quoting Len’s favorite verses. Hal Finney—another pioneer battling terminal illness—uploaded a video from his wheelchair: “Some choose total disappearance. It’s their right.”

Yet the internet rejects coincidences. Sorting Len’s belongings revealed 2007 sketches of tree-like structures resembling blockchains. A college roommate suddenly recalled Len drunkenly declaring: “I’ll create money even God can’t trace.”

Most chilling: in the weeks before his death, Len sent encrypted files to close friends. Decrypted, they contained a recording: “If you’re hearing this, I’ve become a hash… Remember, the important keys are hidden in the genesis block’s hex.”

V. The Unbreakable Will

Today, Bitcoin pilgrims visit the Brussels apartment. The building manager reports hallway lights flickering at midnight—“as if someone is checking an old mailbox.”

Cryptographers still debate the clues: Why did Satoshi avoid American idioms? (Len’s native tongue carried Dutch influences.) Why Belgian coding patterns in early Bitcoin? Why, on the day of Len’s death, did an anonymous account send a blank email to Satoshi’s old address?

Perhaps the saddest clue came from Meredith’s inventory: in Len’s wallet’s hidden compartment, a 2010 receipt for “graphics cards”—noted: “For the child that can never be named.” Early Bitcoin mining relied on GPUs.

The rain falls again. I close my screen filled with code, recalling Len’s words from an old mailing list: “Anonymity isn’t hiding—it’s the freedom to be anyone.”

Satoshi’s wallets remain untouched: a million bitcoins in eternal silence.

The numbers never lie. They have simply become his epitaph.