لطفا منتظر باشید ...
Recipe 7.17 Backing Up a Private Key
7.17.1 Problem
You want to protect against losing your
private key or forgetting your passphrase. (And thereby losing the
ability to decrypt your files.)
7.17.2 Solution
Store your key pair in an
offline, physically secure location, together with a throwaway
passphrase. First change the passphrase temporarily to something you
do not use for any other purpose. This will be your
"throwaway" passphrase.
$ gpg --edit mykey_id ...
Command> passwd
...follow the prompts...
Then make a copy of your key pair that uses this throwaway
passphrase, storing it in the file mykey.asc:
$ gpg -a -o mykey.asc --export mykey_id
$ gpg -a --export-secret-keys mykey_id >> mykey.asc
Finally, restore the original passphrase to your key on your keyring:
$ gpg --edit mykey_id ...
Command> passwd
...follow the prompts...
You now have a file called mykey.asc that
contains your key pair, in which the private key is protected by the
throwaway passphrase, not your real passphrase. Now, store this file
in a safe place, such as a safety deposit box in a bank. Together
with the key, store the passphrase, either on disk or on paper.To guard against media deterioration or obsolescence, you can even
print mykey.asc on acid-free paper and store the
printout with the media. Or maybe have the key laser-engraved on a
gold plate? Whatever makes you feel comfortable.
7.17.3 Discussion
Imagine what would happen if you forgot your passphrase or lost your
secret key. All your important encrypted files would become useless
junk. Even if you are sure you could
never forget your passphrase, what if you become
injured and suffer amnesia? Or what about when you die? Could your
family and business associates ever decrypt your files, or are they
lost forever? This isn't just morbid,
it's realistic: your encrypted data may outlive you.
So plan ahead.If gpg could output your secret key to a file
unencrypted, we would do so, but it has no such option. You could get
the same effect by temporarily changing to a null passphrase and then
doing the export, but that's dangerous and awkward
to describe, so we recommend a throwaway passphrase instead.Storing your plaintext key anywhere is, of course, a tradeoff. If
your passphrase exists only inside your head, then your encrypted
data are more securebut not necessarily
"safer" in the general sense. If
losing access to your encrypted data is more worrisome than someone
breaking into your safety deposit box to steal your key, then use
this procedure.Other cryptographic techniques can address these issues, such as
secret-sharing, or simply encrypting documents with multiple keys,
but they require extra software support and effort. A secure,
plaintext, backup copy of your private key ensures that your data
will not be irretrievably lost in these situations. You can, of
course, create multiple keys for use with different kinds of data,
some keys backed up in this way and others not.While you're visiting your safety deposit box, drop
off a copy of your global password list as well. [Recipe 6.15] Your heirs may need it someday.
7.17.4 See Also
gpg(1).
