Two years ago when “Michael,” an owner of cryptocurrency, contacted Joe Grand to help recover access to about $2 million worth of bitcoin he stored in encrypted format on his computer, Grand turned him down.
Michael, who is based in Europe and asked to remain anonymous, stored the cryptocurrency in a password-protected digital wallet. He generated a password using the RoboForm password manager and stored that password in a file encrypted with a tool called TrueCrypt. At some point, that file got corrupted and Michael lost access to the 20-character password he had generated to secure his 43.6 BTC (worth a total of about €4,000, or $5,300, in 2013). Michael used the RoboForm password manager to generate the password but did not store it in his manager. He worried that someone would hack his computer and obtain the password.
“At [that] time, I was really paranoid with my security,” he laughs.
Grand is a famed hardware hacker who in 2022 helped another crypto wallet owner recover access to $2 million in cryptocurrency he thought he’d lost forever after forgetting the PIN to his Trezor wallet. Since then, dozens of people have contacted Grand to help them recover their treasure. But Grand, known by the hacker handle “Kingpin,” turns down most of them, for various reasons.
Grand is an electrical engineer who began hacking computing hardware at age 10 and in 2008 cohosted the Discovery Channel’s Prototype This show. He now consults with companies that build complex digital systems to help them understand how hardware hackers like him might subvert their systems. He cracked the Trezor wallet in 2022 using complex hardware techniques that forced the USB-style wallet to reveal its password.
But Michael stored his cryptocurrency in a software-based wallet, which meant none of Grand’s hardware skills were relevant this time. He considered brute-forcing Michael’s password—writing a script to automatically guess millions of possible passwords to find the correct one—but determined this wasn’t feasible. He briefly considered that the RoboForm password manager Michael used to generate his password might have a flaw in the way it generated passwords, which would allow him to guess the password more easily. Grand, however, doubted such a flaw existed.
Michael contacted multiple people who specialize in cracking cryptography; they all told him “there’s no chance” of retrieving his money. But last June he approached Grand again, hoping to convince him to help, and this time Grand agreed to give it a try, working with a friend named Bruno in Germany who also hacks digital wallets.
Grand and Bruno spent months reverse engineering the version of the RoboForm program that they thought Michael had used in 2013 and found that the pseudo-random number generator used to generate passwords in that version—and subsequent versions until 2015—did indeed have a significant flaw that made the random number generator not so random. The RoboForm program unwisely tied the random passwords it generated to the date and time on the user’s computer—it determined the computer’s date and time, and then generated passwords that were predictable. If you knew the date and time and other parameters, you could compute any password that would have been generated on a certain date and time in the past.
If Michael knew the day or general time frame in 2013 when he generated it, as well as the parameters he used to generate the password (for example, the number of characters in the password, including lower- and upper-case letters, figures, and special characters), this would narrow the possible password guesses to a manageable number. Then they could hijack the RoboForm function responsible for checking the date and time on a computer and get it to travel back in time, believing the current date was a day in the 2013 time frame when Michael generated his password. RoboForm would then spit out the same passwords it generated on the days in 2013.
There was one problem: Michael couldn’t remember when he created the password.
According to the log on his software wallet, Michael moved bitcoin into his wallet for the first time on April 14, 2013. But he couldn’t remember if he generated the password the same day or some time before or after this. So, looking at the parameters of other passwords he generated using RoboForm, Grand and Bruno configured RoboForm to generate 20-character passwords with upper- and lower-case letters, numbers, and eight special characters from March 1 to April 20, 2013.
It failed to generate the right password. So Grand and Bruno lengthened the time frame from April 20 to June 1, 2013, using the same parameters. Still no luck.
Michael says they kept coming back to him, asking if he was sure about the parameters he’d used. He stuck to his first answer.
“They really annoyed me, because who knows what I did 10 years ago,” he recalls. He found other passwords he generated with RoboForm in 2013, and two of them did not use special characters, so Grand and Bruno adjusted. Last November, they reached out to Michael to set up a meeting in person. “I thought, ‘Oh my God, they will ask me again for the settings.”
Instead, they revealed that they had finally found the correct password—no special characters. It was generated on May 15, 2013, at 4:10:40 pm GMT.
“We ultimately got lucky that our parameters and time range was right. If either of those were wrong, we would have … continued to take guesses/shots in the dark,” Grand says in an email to WIRED. “It would have taken significantly longer to precompute all the possible passwords.”
Grand and Bruno created a video to explain the technical details more thoroughly.
