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- John Cantrell has published an article that shows how he hacked into a Bitcoin address to win 1 BTC.
- The Hack was part of a competition organized by the CIO of Altana Digital.
In an article on Medium the developer John Cantrell, told how he was in a Bitcoin address hack in order to receive a reward. In the framework of a competition organized by the CIO of Altana Digital, Alistair Milne, took Cantrell 30 hours to find approximately 1.1 trillion possible Mnemo-phrases for 4 words, 8 of Milne specified words. The address required to enter the 12-word Seed Phrase.
Milne launched the competition in may and published hints on his Social Media Accounts. In this way, the participants should be the words of a 12-word Seeds to guess that protected the Bitcoins. The last notes of the 4 words should be posted, according to Milne at the same time, to prevent someone guesses it. But Cantrells performance showed that only 8 were needed. Although, as the developers said, substantial efforts will be required.
How to crack a Bitcoin address?
In order to be able to guess the remaining words and win the Bitcoins, has written to the developer first, a program to measure the time, the estimated performance and the real possibility to guess the 4 remaining words, as Cantrell stated:
The strategy that I wanted to apply was to calculate a starting and an ending, between which I had to iterate on the basis of a set of known command words. For each number I would calculate this number, corresponding address and then check if it was the address with 1 BTC. If it was the address, I would then create a transaction and sign it, to send the money in a controlled Wallet.
According to the estimates of the developer, he would have needed 25 years to guess the 4 words. So he had to rent a more powerful machine: a 32-core CPU-optimized machine from Digital Ocean. This enabled him to examine of 8,000 per second.
However, this was not enough and would have needed a lot of time and 1000 times the computing power to guess that the first four words. So he rented about a dozen graphics cards on one GPU marketplace, and leased 40 GPUs of Microsoft’s Azure network. In total, he spent about $ 500 in order to obtain more computing power. The result was as follows:
At the peak, I tested about 40 billion Mnemomic phrases per hour. This means that the Test of the 1 trillion Mnemonics is expected to have about 25 hours it lasted. I knew that it should take, on average, only 50% of the time (depending on what the 9. The word was actually).
After several hours without a result, the developers began to Worry. For a Moment he lost hope and was going to the Computer to turn off a new Version to try out, but after he had tried 91% of the possibilities, he found the solution.
With the four remaining words, he was able to gain access to the Wallet. Out of fear that someone might try to prevent the transaction, he set a high fee of 0.01 BTC, in order to accelerate the validation. Minutes later, validated his transaction, and in a Block included. The Bitcoins belong to him irrevocably. On the question of a community member Cantrell replied that he would have used the same mechanism 309.485.009.821.345.068.724.781.056 days to guess the 12 words in the whole Seeds, in order to obtain access to the address.
Last updated on June 19, 2020–
