Satoshi's 2009 bitcoin.exe rebuilt byte for byte after 17 years, with Opus 5.5 reverse-engineering his build machine

A developer known as t4t5 used Claude Opus 5.5 to work backward to Satoshi Nakamoto's build environment and rebuilt the original 2009 Bitcoin executable, identical down to the byte.

According to the GitHub repository 'bitcoin-0.1-rebuilt', published Oct 18, the file built from source has the same SHA-256 hash as the 6,440,960-byte exe Satoshi shipped in January 2009. The release archive also matches the MD5 and SHA-1 published by the Satoshi Nakamoto Institute.

Bitcoin 0.1 was built once, on Satoshi's own Windows XP machine, and nobody had reproduced it from source. Reading traces left in the binary, the developer matched the compiler (MinGW gcc 3.4.5), library versions and build order. The work also shows Satoshi built his libraries around Nov 28, 2008, upgraded binutils midway, and finished the exe at 23:16 UTC on Jan 10, 2009, then packed it with a WinRAR version that was already over three years old.

Asked whether it is useful, he wrote 'not really,' but 'we can now confirm with certainty that the executable people downloaded matches satoshi's published source code exactly.' The post passed 2,000 likes and 270,000 views.

The repo notes this is the Jan 10 update, not the Jan 8 launch build, of which no verified copy is known to survive.