7 years ago I exported the multibit classic wallet and private key, both encrypted. Only remember the key password now. Problems occurred when I tried to decrypt the key in following ways:
installed MultiBit Classic 0.5.17 from web (might be dangerous).
Created a new wallet and tried "tools--import private key". Chose the old key, input the password and clicked "decrypt". The password seemed correct because there wasn't a fail note, which always appeared for other passwords.
Then, when I clicked "import private key", a fail note said "could not understand address in import file".
To compare I exported a new encrypted private key and followed steps above. It worked well. Though the new key had a wrong timestamp in 2014, it didn't hinder the import.
Used openssl in cmd to do direct decryption, found the only code:
openssl enc -d -p -aes-256-cbc -md md5 -a -in multibit.key -out key.txt -pass 'pass:myPassword'
that can decrypt the new key successfully. When decrypting the old key, it didn't show any error either, no "bad decryption". But the plain text was garbled like
Tried lots of text-code-converter and they only gave different garbled text...
How would this happen? Was the old key exported incorrectly in 2013? Is there any hope?