A paper key is a
machine-readable print of a
cryptographic key. The printed key can be used to decrypt data, e.g. archives or
backup data. A paper key can be the result of an
offline private key protocol. The offline private key can also function as a token in
two-factor authentication
Multi-factor authentication (MFA; encompassing two-factor authentication, or 2FA, along with similar terms) is an electronic authentication method in which a user is granted access to a website or application only after successfully presenting ...
.
The idea is that a digital key to decrypt and recover sensitive or personal data should have long-term durability and not be stored on any computer or network. The length of secure cryptographic keys restricts memorization, so the secret key takes the form of a 2D
barcode
A barcode or bar code is a method of representing data in a visual, machine-readable form. Initially, barcodes represented data by varying the widths, spacings and sizes of parallel lines. These barcodes, now commonly referred to as linear or o ...
, a machine-readable print. Early implementations of a paper key by the company Safeberg use a
Data Matrix
A Data Matrix is a two-dimensional code consisting of black and white "cells" or dots arranged in either a square or rectangular pattern, also known as a matrix. The information to be encoded can be text or numeric data. Usual data size is fro ...
barcode
A barcode or bar code is a method of representing data in a visual, machine-readable form. Initially, barcodes represented data by varying the widths, spacings and sizes of parallel lines. These barcodes, now commonly referred to as linear or o ...
. or human-readable
base 16
In mathematics and computing, the hexadecimal (also base-16 or simply hex) numeral system is a positional numeral system that represents numbers using a radix (base) of 16. Unlike the decimal system representing numbers using 10 symbols, he ...
digits.
"Paperkey - an OpenPGP key archiver"
by David Shaw
The user stores the printed key in a secure location. To avoid abuse, the key can only be used in combination with a ‘normal’ password.
The user can extract the key by creating a digital photo or scan of their paper key and feeding it to cryptographic software that extracts the key to decrypt the data.
See also
* Offline private key protocol
External links
{{DEFAULTSORT:Trusted Paper Key
Key management
Data security