Files · Protected keys
Private keys starting with 6P: what they are
If you are looking at a piece of paper or a file with a string of letters and numbers starting with 6P, you have a password-encrypted private key. The good news: those passwords were typed by a person, not a generator, and that changes the outlook a great deal.
Where that format comes from
It became popular with paper wallets: it let you print a key on paper so that if someone found it, they couldn’t spend anything without the password. It was widely used between 2013 and 2017, especially in printed wallets and physical bitcoin gifts.
So if you have one of these, it almost certainly comes from a sheet of paper. And if it comes from paper, there is almost certainly another half on that same sheet: the address, which is public and lets you check whether it holds a balance. Do that first: see old paper wallets.
What the outlook is
| What you remember of the password | Outlook |
|---|---|
| Two or three candidates | Very good |
| The pattern or style | Good |
| Only the length | Depends; sometimes |
| Nothing | Hard |
| It was random | No |
There is one technical nuance in your favour and one against. In favour: these are human passwords from an era when hardly anyone used managers. Against: this format was designed to be deliberately expensive to test, so fewer candidates per second than an old wallet.dat. On balance, these cases work out often when there is memory to draw on.