PAPERKEY(1) General Commands Manual PAPERKEY(1)
NAME
paperkey - extract secret information out of OpenPGP secret keys
SYNOPSIS
paperkey [--secret-key=FILE] [--output=FILE] [--output-type=base16|raw]
[--output-width=WIDTH]
paperkey --pubring=FILE [--secrets=FILE] [--input-type=auto|base16|raw]
[--output=FILE] [--ignore-crc-error] [--comment=STRING] [--file-format]
paperkey --version
MOTIVATION
As with all data, secret keys should be backed up. In fact, secret
keys should be backed up even better than other data, because they are
impossible to recreate should they ever be lost. All files encrypted
to lost keys are forever (or at least for a long time) undecipherable.
In addition to keeping backups of secret key information on digital me-
dia such as USB-sticks or CDs it is reasonable to keep an if-all-else-
fails copy on plain old paper, for use should your digital media ever
become unreadable for whatever reason. Stored properly, paper is able
to keep information for several decades or longer.
With GnuPG, PGP, or other OpenPGP implementations the secret key usu-
ally contains a lot more than just the secret numbers that are impor-
tant. They also hold all the public values of key pairs, user ids, ex-
piration times and more. In order to minimize the information that has
to be entered manually or with the help of OCR, QR code or similar
software, paperkey extracts just the secret information out of OpenPGP
secret keys. For recovering a secret key it is assumed that the public
key is still available, for instance from public Internet keyservers.
DESCRIPTION
paperkey has two modes of operation:
The first mode creates "paperkeys" by extracting just the secret infor-
mation from a secret key, formatting the data in a way suitable for
printing or in a raw mode for further processing.
The other mode rebuilds secret keys from such a paperkey and a copy of
the public key, also verifying the checksums embedded in the paperkey.
This mode is selected when the --pubring option is used, which is re-
quired in that case. If a passphrase was set on the original secret
key, the same passphrase is set on the rebuilt key.
Input is read from standard-in except when the --secret-key or --se-
crets option is used; output is printed to standard-out, unless changed
with the --output option.
SECURITY CONSIDERATIONS
Please note that paperkey does not change the protection and encryption
status of and security requirements for storing your secret key. If the
secret key was protected by a passphrase so is the paperkey. If the
secret key was unprotected the paperkey will not be protected either.
OPTIONS
--help, -h Display a short help message and exit successfully.
--version, -V
Print version information and copyright information and exit
successfully.
--verbose, -v
Print status and progress information to standard-error while
processing the input. Repeat for even more output.
--output=FILE, -o
Redirect output to the file given instead of printing to stan-
dard-output.
--comment=STRING
Include the specified comment in the base16 output.
--file-format
Paperkey automatically includes the file format it uses as com-
ments at the top of the base16 output. This command simply
prints out the file format and exits successfully.
OPTIONS FOR EXTRACTING SECRET INFORMATION
--output-type=base16, --output-type=raw
Select the output type. The base16 style encodes the informa-
tion in the style of a classic hex-dump, including line numbers
and per-line CRC checksums to facilitate localizing errors in
the input file during the recovery phase. The raw, or binary,
mode is just a raw dump of the secret information, intended for
feeding to barcode generators or the like.
--output-width=WIDTH
Choose line width in the base16 output mode. The default is 78
characters.
--secret-key=FILE
File to read the secret key from. If this option is not given
paperkey reads from standard-input.
OPTIONS FOR RE-CREATING PRIVATE KEYS
--input-type=auto, --input-type=base16, --input-type=raw
Specify that the given input is either in base16 format, as pro-
duced by paperkey, or in raw format. The default, auto, tries
to automatically detect the format in use.
--pubring=FILE
File to read public key information from. It is assumed that
the user can get the public key from sources like public Inter-
net keyservers.
--secrets=FILE
File to read the extracted secrets, the paperkey, from. If this
is not given then the information is read from standard-input.
--ignore-crc-error
Do not reject corrupt input and continue despite any CRC errors.
EXAMPLES
Take the secret key in key.gpg and generate a text file
to-be-printed.txt that contains the secret data:
$ paperkey --secret-key my-secret-key.gpg --output to-be-printed.txt
Take the secret key data in my-key-text-file.txt and combine it with
my-public-key.gpg to reconstruct my-secret-key.gpg:
$ paperkey --pubring my-public-key.gpg --secrets my-key-text-file.txt
--output my-secret-key.gpg
If --output is not specified, the output goes to stdout. If --se-
cret-key is not specified, the data is read from stdin so you can do
things like:
$ gpg --export-secret-key my-key | paperkey | lpr
SEE ALSO
gpg(1), http://www.jabberwocky.com/software/paperkey/
AUTHORS
paperkey is written by David Shaw <dshaw@jabberwocky.com>.
PAPERKEY June 2012 PAPERKEY(1)
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