Don't do what the previous poster said, that isn't necessary

Do this instead:

1- Close Bitcoin-qt
2- PRESS WINDOWS + R key.
3- Write: %APPDATA%
4- PRESS ENTER
5- CUT the file wallet.dat and paste in other location like C:\ (this is a backup of your wallet.dat, should you ever remember your password you can use this to access your lost Bitcoins again)
6- Open Bitcoin-qt again

Tada: Fresh wallet

Same problem here

Seems to be down?

He doesn't seem to be active anymore I'm afraid

Last Active:   May 09, 2013, 09:48:36 AM

First of all, I know the altcoin section might be more appropriate for my questions, but I have already asked my question there, but there wasn't anybody able to help me, so hopefully I'm allowed to ask for help here.

Now on to my problem! I saved a wallet with about ~1600-1700 Yacoin which is worth over 0.25 BTC. I wanted to sell these, but upon opening my wallet, I'm getting the following error:



What I've tried:

1) Deleting everything in the Yacoin folder except the wallet.dat. Same thing.
2) Use the -salvagewallet option. This resulted in the following error:



3) Pywallet. It takes a bit of fiddling to get it to work on Yacoin via the otherversion switch, but I managed to get it to work with a fresh Yacoin wallet. No success with my corrupted version It threw the following errors:

Traceback (most recent call last):
  File "C:\Users\Jaap\Desktop\pywallet.py", line 2059, in parse_wallet
    d['txIn'].append(parse_TxIn(vds))
  File "C:\Users\Jaap\Desktop\pywallet.py", line 2028, in parse_TxIn
    d['sequence'] = vds.read_uint32()
  File "C:\Users\Jaap\Desktop\pywallet.py", line 1942, in read_uint32
    def read_uint32(self): return self._read_num('  File "C:\Users\Jaap\Desktop\pywallet.py", line 1981, in _read_num
    (i,) = struct.unpack_from(format, self.input, self.read_cursor)
error: unpack_from requires a buffer of at least 4 bytes

4) I used an old Yacoin client, which I used during the time I mined those Yacoin. Didn't work either.
5) I inspected the wallet.dat with an Hex Editor. I managed to find the label of the address which holds my Yacoin and I found the address in plaintext. Looking on the Block Explorer, my Yacoin are still there.


I also managed to find a lot of instances of "63 6B 65 79 21 02" or in ASCII "ckey!.", which presumably indicates an encrypted private key follows, correct?

My main questions:
1) How long (in bytes) is the encrypted private key that follows?
2) What algorithm is used to encrypt these private keys and how can I manually decrypt these? (I know the passphrase)
3) I found 244 instances of "63 6B 65 79 21 02" or in ASCII "ckey!.". Is there any way how I can find out which of those belongs to the address which I found in plaintext in the wallet, or will I have to try them all to find the correct one?
4) Once I find the decrypted private key, I can import these via the console with importprivkey, correct?


Thank you very much in advance!

Does anyone happen to know a formula to calculate how long it would take on average to find a block at the difficulty X with hashingpower Y?

Yes.

Still had an old version on my of my mining PCs, but it's crashing with the same error as the one in my first post

Yeah, this wallet is quite old, so it was made with an old version

Pywallet works fine on a new wallet, but fails on the corrupted wallet. I'm getting the following error:

Traceback (most recent call last):
  File "C:\Users\Jaap\Desktop\pywallet.py", line 2059, in parse_wallet
    d['txIn'].append(parse_TxIn(vds))
  File "C:\Users\Jaap\Desktop\pywallet.py", line 2028, in parse_TxIn
    d['sequence'] = vds.read_uint32()
  File "C:\Users\Jaap\Desktop\pywallet.py", line 1942, in read_uint32
    def read_uint32(self): return self._read_num('  File "C:\Users\Jaap\Desktop\pywallet.py", line 1981, in _read_num
    (i,) = struct.unpack_from(format, self.input, self.read_cursor)
error: unpack_from requires a buffer of at least 4 bytes

Okay, so I'm looking through the wallet.dat with a hex editor, and I've managed to find the Yacoin public address that contains my Yacoin in plaintext. Where exactly is the private key stored? And how would I decrypt it manually?

Edit: Trying to use pywallet now to salvage the private key. What value should I pass to the --otherversion= switch so it looks for Yacoin addresses rather than Bitcoin?

Edit2: Since addresses are base58 encoded and since Yacoin addresses start with an Y, that would be 31, correct? Let's see if this works

Edit3: Meh, not working. I've tried the following two commands:

C:\Users\Jaap\Desktop>pywallet.py --datadir="C:\Users\Jaap\AppData\Roaming\YaCoin" --otherversion=31 --dumpwallet

and

C:\Users\Jaap\Desktop>pywallet.py --datadir="C:\Users\Jaap\AppData\Roaming\YaCoin" --otherversion=31 --dumpwallet --passphrase=mypassphrase

Thanks for the link! Unfortunately when I use the -salvagewallet option I'm getting a different error:

Bump

Already tried that. I am getting that error with a completely empty data folder except the wallet.dat file.
Removing the wallet.dat as well and Yacoin loads just fine.

How?

Edit: I'm not sure if that backup was encrypted. I'm fairly positive it was though, but I know the password, so it shouldn't be an issue.

I have an old backup of a YAC wallet containing ~1600 YACoins, but the wallet seems to be corrupt. When I try to start Yacoin with the wallet.dat in the correct directory I'm getting the following error:



I'm offering 100 YAC to whoever can help me recover my ~1600 YAC.

I was wondering if it is possible to use sendmany to specify a change address. Say I want to send 1 BTC to address A while address B is the address from which the client is sending the Bitcoins (Because it's the only address in the wallet containing any BTC), which contains 5 BTC. Can I use sendmany to do the following:

Create a sendmany transaction that:
-Sends 1 BTC to A
-Sends 4 BTC to B

Because address B is the only address containing any BTC, it will use the BTC from that address as the inputs. Since the output amount equals the input amount, this leaves no unspent inputs, so the client won't send any change to a new address C.

So would this be possible? Or will I have to use raw transactions for this? I prefer not to use raw transactions if I don't have to, because of the added risks of bugs causing BTC losses.

Where can I get the latest coin control fork? And will I have to change anything at all to my current API calls to Bitcoind, or will it automatically send change back to the same address from where it came?

I know that Bitcoin-qt generates new addresses to send change to, but I was wondering if this behavior is the same for Bitcoind? If it is, is it possible to disable this feature? I'd like the change to go to the same address as where it came from, so I can always check the balance of a remote wallet. I'm aware of the implications this has for my anonymity. Thank you very much in advance!

OP, please read this page and hopefully you will understand why it's not possible to losslessly compress any data. Some data will actually get bigger: http://en.wikipedia.org/wiki/Pigeonhole_principle

Now I have a _very_ simple example for you. Lets say we want to "compress" 2 bits of data. All the possible datasets are:

00
01
10
11

Now please compress those 4 datasets so that they will all get smaller. Impossible. Unless you use something like:

00 -> 0
01 -> 1
10 -> 10
11 -> 11

But then my next question will be:

Now please compress

0
1

Impossible again, since you've already used 0 and 1 to "compress" 00 and 01. So these 2 "datasets" will have to get bigger by definition, or you will have a collision.

The reason why compression works, is that it encodes sequences and often reoccurring patterns. But as we just saw, there will be datasets (random data) that will actually increase in size if a lossless compression algorithm is used on it. And it just so happens that movies and pictures are very similar to random data. Unless, of course, you use raw pictures/movies, but these files are huge. And believe me when I say you won't beat current algorithms which have been developed over the years by a lot of skillful people.

The thing I think you're missing, is this: You are talking about reference points. This dictionary to which these reference points point, also needs to be stored somewhere. And even if you use referencing, you will still run into the Pigeon Hole Principle. 2 bits of data have 4 possible combinations, so in order to be able to reference to those 4 possible combinations you need 4 different reference points.....Which require 2 bits of data.

Hope this helps.