I lost the device with my Android Bitcoin Wallet late 2013. At the time, I had stored a 'wallet backup' file. It has no extension, is 240 bytes, and begins with 'U'.
With only that file, is it possible to recover the value of the Bitcoin?
Please explain what the 240-byte string is, and what else would be necessary to recover the Bitcoin value.
That is very likely to be the "Bitcoin Wallet for Android" by "Bitcoin Wallet Developers" also sometimes known as the Schildbach wallet.
Other people on Reddit discuss having a file of that size created by this wallet.
Apparently the backup format changed from text-based Base-58 encoded private keys to a binary Protobuf wallet file.
It seems likely that the backup was encrypted and that you will therefore need to know the wallet password. I've no idea if encrypting the backup was optional in that software in 2013.
The process for either form is described here:
This document describes how you can use a backup file on a standard PC to recover your Bitcoins. Normally, this shouldn't be needed. It is much preferred to just use Options > Safety > Restore wallet from within the Bitcoin Wallet app if you can.
i.e. first try installing the Bitcoin Wallet app and using its recovery menu.
Other discussion:
The 240-byte data starting with "U" can be an AES-256 encoded string containing your key.
You can easily decrypt it with the openssl command if you remember your password or have some idea of what the correct password might be.
Here is the approximate command which may decode your key:
openssl enc -d -aes-256-... ... -in bitcoin-wallet-keys.key -out bitcoin-wallet-keys.dec
This command with several additional command line switches can decode your key, so you will be able to import the decoded key it into any bitcoin wallet app.
I recently managed to decrypt my 240 byte key file created in 2013 after the Bitcoin Wallet Android app failed to import the file because they changed the wallet file format.
Do not hesitate to contact me if you need any help with that.
Regards.
