In the digital world, though, it’s a simple matter to then transfer those Bitcoins to another address. And another. And another. This is done to obscure a trail and mask the flow of funds, kind of like money laundering. By May 27, the FBI had identified at least two dozen different Bitcoin addresses used in the distribution. Then, finally, most of it, 69.6 Bitcoins in total, was funneled back to one last address.
It’s here that the feds pounced — and where the story gets murky.
Somehow, they had the private key for this last address. Most cryptography works on a public-private key protocol. The public key can be thought of as similar to an email address, and the private key the password. Except these passwords are extremely long and almost impossible to guess.
Law enforcement agencies don’t like to share their tradecraft, so how the FBI managed to get the key to this stash isn’t yet public. There’s a chance that the FBI hacked the hackers, or that someone else did and passed the key to the Bureau. Or maybe an informant handed it over.
There’s also the possibility that this final address didn’t actually belong to the hackers, but to a cryptocurrency exchange….