Investigating Cryptocurrencies

CHAPTER 6Wallets

“Sometimes in the quest for enlightenment the only thing that gets lighter is your wallet.”

—Steve Maraboli

The Internet says: “A cryptocurrency wallet is a secure digital wallet used to store, send, and receive digital currency like Bitcoin.” I won't tell you where that quote comes from, because I wouldn't want to embarrass them, but it's wrong. In fact, it's technically wrong in virtually every way—a wallet doesn't store your bitcoin, and because it doesn't store them, it can't send or receive them! I'm being a little picky here—I know exactly what they mean by the statement—but the reality is important: the wallet simply maintains a list of private and public keys that it can resolve. By either watching a local copy of the blockchain or communicating with a copy belonging to another full-node user, the wallet simply builds a balance from the transactions it can control.

A forensic lab contacted me some months back and asked if I could “recover a suspect's bitcoin from a hard drive.” I told the analyst that his suspect's computer never had any bitcoin stored on it in the first place. He sounded confused and told me that the suspect had admitted to storing ill-gotten gains in bitcoin on his computer. I sensed that fun could be had, so I told my new friend that I already had his suspect's bitcoin on my computer. Silence. I broke the silence by asking him if he would like me to e-mail those bitcoin to him. Silence continued. I think he was trying to decide ...