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1  Economy / Auctions / Hard drive with 1000+ BTC, totally inaccessible. on: July 09, 2019, 04:19:18 AM
Selling a hard drive I had lost back in 2011 which had a few thousand bitcoins (not sure how much, I'd estimate 3000, definitely more than 1000). The wallet is not encrypted but the hard drive itself (My Passport 1 TB) is encrypted with a password which I for the life of me cannot remember. I know it has 10 characters exactly but that's about it, and it's not feasible for me to bruteforce.

Starting price: 0.03 BTC
Increments: 0.005 BTC
Buy now: 1 BTC

2  Bitcoin / Development & Technical Discussion / Need some help with recovering one of my old wallets on: July 08, 2019, 09:13:29 AM
It's been a while since I've been a part of the bitcoin project. Got extremely bitter after Gox collapsed since I had 90% of my holdings on there. After a recent attic cleaning, I found my old drive, which is supposed to have the other 10% (I believe it was in the thousands of bitcoins, definitely more than one thousand, not exactly sure). I tried every possible password combination I could remember, but it didn't work. The only thing I know for sure is that the password is 10 characters long.

This isn't feasible for me to bruteforce on my home computer, so I was wondering if anybody has experience with smarter algorithms that would be able to decode my wallet passphrase in a shorter amount of time (I'm hoping within a week or so). I've been in a financial crunch recently, and to be honest, had mostly forgotten about cryptocurrencies, so finding my old drive was a very welcome surprise. Feels good to be back in the game. Also, if anyone has contacts with some good wallet recoverers, please let me know, and I will do my best to arrange for an in-person meeting.
3  Bitcoin / Development & Technical Discussion / Stop using floating point! on: June 09, 2011, 03:15:45 AM
Can we stop with this nonsense?

+    if (params[0].get_real() != 0.0)
+        nAmount = AmountFromValue(params[0]);        // rejects 0.0 amounts


          if (strMethod == "sendtoaddress"          && n > 1) ConvertTo<double>(params[1]);
+        if (strMethod == "settxfee"               && n > 0) ConvertTo<double>(params[0]);


Please learn to use fixed-point arithmetic, people... this is not a pet project anymore, it's a financial application that at the moment holds $181 million USD worth of people's savings.

I think you might need a lesson on how floating point works.
In short, results of rounding, calculations and comparisons may vary depending on compiler, optimizations, or architecture used.
Furthermore, there are other non-obvious semantics, such as negative zeros, infinities, NaNs, etc.

I know in this case the comparison with 0.0 is probably not problematic, but for instance, you don't want someone to send a transaction of 0.12345678 bitcoins and then due to rounding conversions you actually send 0.12345679 bitcoins instead. Or someone to set a transaction fee of 0.2 and instead it gets set to 0.19999999.

It is NOT acceptable for financial applications to use floating point numbers to represent monetary values.
Governments have strict regulations against this for banks, for obvious reasons.

Please, please avoid using floating point arithmetic and educate yourselves why you should do that.

For example, there's a reason why Satoshi avoided floating point calculations in many places (e.g. difficulty calculations... you really don't want different machines having a different concept of what the difficulty is).

What you really want is to convert strings directly to fixed-point numbers (probably with BigDecimals if uint64 is not enough for 21,000,000*10^8 individual units) and vice-versa.
Always do calculations, comparisons and range checks with fixed-point arithmetic.

http://objectopia.com/2009/07/03/stop-using-floating-poin/
http://programmers.stackexchange.com/questions/62948/what-can-be-done-to-programming-languages-to-avoid-floating-point-pitfalls
http://www.theregister.co.uk/2006/08/12/floating_point_approximation/
http://hal.archives-ouvertes.fr/docs/00/28/14/29/PDF/floating-point-article.pdf

... and so on and on...

Same advice goes for the code of any website that deals with bitcoins (MtGox and mining pools come to mind...).
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