Defcon Speaker Discusses Rescuing $300K Worth Of Bitcoin From An Encrypted File

Defcon speaker discusses rescuing $300k worth of bitcoin from an encrypted file. Defcon 28 “safe mode” presentations became interesting on August 5, when ex-Google employee Mike Stay shared a tale about how he saved bitcoin ( BTC) worth $300k from an encrypted zip file.

He said “About six months ago, a Russian guy contacted me on Linkedin with an intriguing offer,” May said on Youtube. “He had hundreds of thousands of dollars in Bitcoin keys locked in a zip file, and he couldn’t remember the password. Could I break into it for him?”

The anonymous Russian investor wanted access to the bitcoins worth roughly $300,000. Stay said the anonymous client found his name when he stumbled upon an old cryptanalysis paper he wrote 20 years ago.

Stay explained that the Russian purchased all the coins in 2016 for around $10k. However, the investor put the bitcoin into an encrypted zip file and after some time passed, he forgot his password.

“In that attack, I needed five files to break into a zip archive,” Stay recalled. “This one only had two files in it. Was it possible? How much would it cost? We had to modify my old attack with some new cryptanalytic techniques and rent a GPU farm, but we pulled it off.” 

According to Stay, it costed him around $7k to pull off the attack against the encrypted zip file. Stay said that he also received help from the CEO of Pyrofex, Nash Foster who is also an ex-Google employee. Stay detailed that he built his own program to try different password techniques and at first the job was very difficult.

[image: Markus Spiske]

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