Decrypt .key old multibit wallet

[evergreentrone]

Hello Guys ! 

I find an old file .key from multibit that i used a long time ago. The file is encrypted and i try to put in multibit software but doesn't work !

I don't remember if i use a password but when i used multibit i just open the software and used it..
I think when i use the software for payment, there is a creation of file.key ?? and it is automatically encrypted ? i'm not sure of the functioning

Somebody have an idea to decrypt .key file ? and a procedure to do it ? 

Thanks brothers ! 

[NeuroticFish]

Make a copy of the key file and open it with a text editor (notepad?)

In the file ignore the lines that start with #.
If you have at least one line that looks like
Kxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx 2021-12-02T11:28:19Z
or
Lxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx 2021-12-02T11:28:19Z
(obviously another chars instead of x) then you're good, you can import the private key into Electrum.
Please don't post it anywhere online.

If the file looks different, i.e. it starts with U2F, then it's encrypted and you need to remember your password (and if you don't remember it then you have a problem).
If it's not password protected, you can import it into Electrum as P2PKH:Kxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

(Make sure you've got Electrum from electrum.org and verified it too.)

[o_e_l_e_o]

To follow on from NeuroticFish's comment:

If the file is encrypted, then you can decrypt it via OpenSSL. The instructions for doing so are here: https://github.com/Multibit-Legacy/multibit/wiki/Export%20and%20limited%20import%20of%20private%20keys

The command you need to run is:

Code:

openssl enc -d -p -aes-256-cbc -a -in \<ciphertext file\> -out \<plaintext file\> -pass pass:\<password\>

If it is encrypted and you cannot remember the password, then you can use btcrecover to attempt to bruteforce it if you have a vague idea of what it might be: https://btcrecover.readthedocs.io/en/latest/

[evergreentrone]

Thanks you guy ! i will check your comments and come back to you soon