Nearly five months after the August 2008 exchange, Satoshi wrote to Adam Back one last time, the day after Bitcoin v0.1 was released. The load-bearing line of the email — Satoshi’s own announcement of the v0.1 release to one of the first cypherpunks he had contacted — reads:
Satoshi Nakamoto (email to Adam Back, January 10, 2009, 6:46:45 PM UTC)I just released the open source implementation of my paper, Bitcoin v0.1. Details, download and screenshots are at
www.bitcoin.org
To give Back a high-level sense of how the project was being received, Satoshi forwarded part of Hal Finney’s response from the cryptography mailing-list thread. The Finney quote is independently published in the metzdowd.com cryptography mailing-list archive and is also in the Finney response entry (2008-11-13); the passage Satoshi specifically forwarded was:
Hal Finney (Cryptography mailing list post, November 13, 2008, 4:24:18 PM UTC)One thing I might mention is that in many ways bitcoin is two independent ideas: a way of solving the kinds of problems James lists here, of creating a globally consistent but decentralized database; and then using it for a system similar to Wei Dai’s b-money (which is referenced in the paper) but transaction/coin based rather than account based. Solving the global, massively decentralized database problem is arguably the harder part, as James emphasizes. The use of proof-of-work as a tool for this purpose is a novel idea well worth further review IMO.
This is the last known direct communication between Satoshi and Adam Back. Back did not engage with Bitcoin until 2013, and later founded Blockstream in 2014. A 2025 profile quotes him saying he initially failed to read the whitepaper carefully, “probably my biggest mistake.” The five-email chain — running from Satoshi’s first email to Back on 2008-08-20 to this final notice on 2009-01-10 — documents Satoshi’s outreach to the creator of Hashcash, the referral that surfaced Wei Dai’s b-money, and Satoshi’s final notice that the working system had launched.
This notice to Back falls inside the same dense five-day stretch — three releases, a private email to Finney, and now this one — that the launch-environment analysis reads as evidence of an unusually concentrated block of free time around Bitcoin’s launch.
