[I do not design a cracker!]

For more than 9 months I have been developing a treasure hunter that will allow to return lost bitcoins in abandoned wallets. https://bitcointalk.org/index.php?topic=5213781.msg53484243#msg53484243
I do not design a cracker! It will not be able to crack modern wallets (created after 2012), old abandoned wallets only (containing up to 60% of coins, by the way) using their flaws.
Initially, it was a individual device using mining chips as a coprocessor(s) for a number of operations. This can significantly reduce the cost of the device compared to a fully FPGA solution.
However, in just a few days many popular ASICs (T9/S9 etc.) will become scrap. These are millions of free co-processors. Design a control board that can turn them into "seed-pick" seems like a good idea.

I would like to know the opinion of the community, will such a control board for the resurrection of bitmain scrap be interesting for ASIC's owners?

PS. A little about the reliability of wallets, millions years of searching and similar nonsense. Both in mining and in hunting, luck is at the basis. Finding a block using one ASIC is also difficult like finding a treasure with my device. The pool is effective in both cases.

[Update. 6 march 2020.]

Happy New Year at all!

On this forum have repeatedly discussed ways to crack wallets in the Bitcoin blockchain. Typical hacking methods are key enumeration (LBC https://lbc.cryptoguru.org/about) and dictionary attack / brain wallets (https://eli5.eu/brainwallet/).
It is believed that breaking a wallet takes millions of years, but let me disagree. These calculations were done for household PCs.
In fact, there are only two bottlenecks. This is the key generation speed and the key verification speed.

Today, the mining chips make 71 Gh/s (BM1387). Bitfury Clarke is already 120 Gh/s. BM1391 produces 170-200 Gh/s, 1397 - already 440-500 Gh/s (in S17+). Do not forget that this is the speed of a double SHA-256 (SHA-256).
If we take the standard algorithm for addresses calculating (https://gobittest.appspot.com/Address) it is not difficult to notice that most of the steps are the same SHA-256 and SHA-256 (SHA-256). One RIPEMD-160 stage and several bit shifts. Is it possible to use the mining chip as a coprocessor when generating keys? Yes, it is possible, but more on that later.

The second bottleneck is checking the balance at the address found. The system should turn to the blockchain and make sure that there are bitcoins on the addresses belonging to the key pair. Compared to hashing speed, it is very slow.
The situation changes if you know a wallet or a private key with a balance. In this case, you should only verify a few bytes.

Armed with this knowledge, I assembled the simplest device based on the S9 hashboard and Cyclone IV FPGA evaboard. This works correctly and I was able to crack test wallets with a simple (low order) key.

Findings:
1. A hashboard is poorly suited for simultaneous computing. It is necessary to connect the chips in parallel, but not in a daisy chain.
2. It is necessary to organize the instruction pipelining in the FPGA for acceleration of calculations.

Now a little about the economy. Why is all this necessary?
I do not want to steal user funds. This is not possible in my system if your wallet is not generally known.
However, there are a lot of forgotten wallets in the blockchain. Some wallets contain thousands of bitcoins. And these wallets remain motionless for many years. You can consider this as a treasure, which has the right to change the owner, imho.

Take for example the Antminer S17e (64Th), whose current profitability is 0.5 btc/year.
The device contains 144 BM1397 chips with approximately 440 Gh at each.
We’ll make the calculation for a wallet protected by seed phrase with a 12-word. The English BIP39 dictionary contains 2048 words. With high probability the old wallet is encrypted in English (or Hex, lol).
((2048 ^ 12) / (144 * (440^9))) / (86400 * 365) = 1939618 years it will take one ASIC to search for all the combinations.
However, if we’ll track 10,000 wallets, then 1939618/10000 = 194 years to search for at least one match. And even if we have 100 ASICs, it turns out 2 years to search for at least one match (based on average luck).
These calculations are very simplified, but they show the order of numbers.

For 2 years, these same 100 ASICs will get 2*100*0.5 = 100 bitcoins. Provided there are no changes in the network’s hashrate and the power of ASICs (no).

At the same time, the difficulty of the seeds of abandoned wallets will never change.
And finding at least one wallet like 1FeexV6bAHb8ybZjqQMjJrcCrHGW9sb6uF can pay for the mining of 100 ASICs for 1600 years. Their name is Legion 12ib7dApVFvg82TXKycWBNpN8kFyiAN1dr, 12tkqA9xSoowkzoERHMWNKsTey55YEBqkv, 1PeizMg76Cf96nUQrYg8xuoZWLQozU5zGW etc.

Thus, mining abandoned addresses is more profitable than mining new coins. Over time, the situation will change in this direction IMHO.

WBR, Ossy.

Update. 6 march 2020.
Pic1 - Structure
Pic2 - Algorithm
1. Defined prototype architecture.
2. The distribution of tasks is determined.
3. Alpha version of bitstream is tested.

Tasks are shared between mining chips and FPGA. In current configuration the prototype is capable to generate (and compare) up to 1500G keys (addresses) per second.
The current prototype is contains only 20 mining chips. After improving the technology computing power will be multiplied.