Fields of Bitcoin wallet hashes

The following content was written by CryptCrypt on April 06, 2021, 06:30:15 PM in the thread Wallets from 2014 vs Wallets from 2021. All content is owned by the author of the bitcointalk.org post. (original)

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Hello, today I bring you a classic.

I am trying to recover a wallet.dat with date Feb 2014 of which I DO NOT REMEMBER THE KEY !!!
Wait, wait … Don’t go yet, this gets better …

Actually, I remember half of the password, so I downloaded btc-qt v0.21.0 and loaded the wallet and, initially, there was no problem and I loaded it without errors. Indeed, the wallet is encrypted.

Well, I downloaded btcrecover , as I said, I will only need 4/5 characters to get it and I have a couple of powerful GPUs …
So I have tried btcrecover with a wallet of btc-qt v0.21 (just created, so I know the key) and I made it difficult for btcrecover. After 19million passwords I got the correct one.

At this point, I tried the wallet from 2014 and there was no way. HOWEVER, I had other wallets from 2015 (ltc, doges) and another from btc from 2016 of which I DID NOT REMEMBER THE KEY. The 2015 ones I didn’t get any but the 2016 btc one did found it (I put patterns, etc and it took it out after 3h testing).

Furthermore, the size of the 2014 wallet is 70kb while an empty wallet from 2021 is 1.5mb

I downloaded a snapshot of Arch Linux from 2014 that included the btc v0.9.0 , with which I created the original wallets and YES it’s size is 70kb . I changed the passphrase of this one and the key was recovered by btcrecover .

I thought that the format of the Wallet would be different but … no. I still find it very strange that I do not get the btc key but I do with the other currencies / versions …

I passed the wallets through the bitcoin2john.py (which I don’t know very well what it does, I suppose it decrypts it … but without a password or anything? Any ideas?) And it got me the next.




As you can see, those of 2014 and 2015 have one less character. I don’t know if this has something to do with it or not.
The btc-qt v0.21 does not give me errors when loading the 2014 and 2015 wallets , in fact it detects the movements that there were. The btcrecover does not show any error either (I don’t know, something like the wallet was not formatted correctly or something like that, but no …)

I’m also not sure what each fields represents:



At this point, I’m a bit stuck. I’m not sure what to do… Before leaving computers for eons trying to get the password, I prefer to exhaust the possibilities and understand well the fields of wallets and everything that surrounds them.

So my doubts are:
1. What does bitcoin2john.py do?
2. What does each field of the wallet represent? ? Link with info?
3. Any ideas about wallet versioning?
4. Any place where I can find technical information of this level?
5. And more importantly … Any ideas to keep trying to decrypt the wallet?

PS: In 2015/2016 I took out almost all the bitcoins, there were only a few satoshis that today are worth 8€ … so it pisses me off, but I don’t want to commit suicide thinking I’m a millionaire xD

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The following content was written by achow101 on April 06, 2021, 07:10:42 PM in the thread Wallets from 2014 vs Wallets from 2021. All content is owned by the author of the bitcointalk.org post. (original)

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This is expected. Prior to BIP 32 HD wallets (introduced in Bitcoin Core 0.13 in 2016), wallets pregenerated 100 keys (for both receiving and change). After BIP 32 HD wallets, wallets pregenerated 2000 keys (1000 for receiving, 1000 for change). This causes the size difference.

The format has not changed. Compatibility is maintained.

It does not. That 3rd parameter is a number of iterations to do and is based off of a benchmark of your computer that is done at the time encryption is added.

This is expected. Compatibility is maintained.

The format is as follows:

length of encrypted key is always 64. The encrypted key is a 32 byte key which means it is 64 characters.
encrypted key is the encryption key which itself is encrypted with your passphrase. Your passphrase is hashed to get the key that is used to encrypt this encrypted key.
length of salt is always 16. The salt is 8 bytes which means it is 16 characters.
salt is the salt. It is randomly generated. The salt is combined with your passphrase to generate the key used to encrypt the actual encryption key.
derivation method iteration count> is the number of times to run the hash function that is used to derive the encryption key from your passphrase.
length of derivation method is always 2. The derivation method is stored as a single byte number, so it is always 2 characters.
derivation method is an integer that indicates the function to be used to derive the encryption key from the passphrase. Currently there is only one method, SHA512, and it is indicated with the number 0.
length of additional parameters is always 2. There are no additional parameters, so it is represented by a single byte of 0, which makes the length 2 characters.
is always 00. There are no additional parameters, so it is always a 0 byte.

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The following content was written by NotATether on April 07, 2021, 06:11:10 AM in the thread Wallets from 2014 vs Wallets from 2021. All content is owned by the author of the bitcointalk.org post. (original)

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People mainly run bitcoin2john on wallet files to get the hash, which can then be attacked by hashcat.


Achow gave you a good answer for this so I will skip to the next one.


If a new wallet version ever changes how the hash is created, the outputs of bitcoin2john will have different values, for example salt length or number of rounds. It just scrapes this information from the wallet file.


The next step is to download and run hashcat and run it with the options hashcat -a 0 -m 11300 {paste the hash here} {dictionary file}. -a 0 stands for attack mode 0 which just uses a dictionary file with a password on each line, it’s good if you have a large number of passwords you think you used or you used an easy-to-guess password. There’s also a “mask mode” you can toggle to construct a pattern to match each characters of a potential pattern against. -m 11300 interprets the hash as one from a Bitcoin or Litecoin wallet.dat file, and it’ll probably work for your dogecoin wallet too. Then you paste the hash

For the hash you need to paste the entire line you for from bitcoin2john.py. Then you need to make a dictionary file or download one from the internet. But if you remember using some unique password then you’re probably better off making the file yourself.

Instead of putting the hash on the command line you can also put all 5 hashes in a file and pass that in place of the hash.

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You don’t need to understand every field of the bitcoin hash because the important part is just pasting it into into hashcat and it’ll do the brute forcing work for you.

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