1.7 KiB
Paper-Secret
Shamir Secret Sharing on paper using gfshare.
Installation
PyPi
Dependencies
Required and optional dependencies with example how to install them for Arch Linux.
gfshare is required to split (enpaper) and merge (depaper) the secret.
See man gfshare for an explanation of Shamir Secret Sharing in gf(2**8).
sudo pacman -S --needed libgfshare
qrencode and imagemagick (convert) are required to create and merge QR-codes during the split process.
One can pass -q to enpapaer to skip this step.
sudo pacman -S --needed qrencode imagemagick
enscript and ghostscript (ps2pdf) are required to create a PDF containing the split secret in text form.
One can pass -t to enpaper to skip this step.
sudo pacman -S --needed enscript ghostscript
Usage
Create a file with secret content:
cat > secret.txt
Split the secret into 5 lines:
enpaper secret.txt
Manually delete up to 2 of the 5 lines in secret.txt_txt.txt.
Then recreate the secret:
depaper secret.txt.split-text.txt
Print the secret:
cat secret.txt.split-text.txt.merged.txt
Notes
Manually reconstructing the secret from k strings:
- For each string of the k strings
- Create a file which name begins with
partand ends with a dot and the first three characters of the string- For example
part.112
- For example
- Convert the 3rd to last character from base64 to binary and insert it into the file
- Create a file which name begins with
- Execute
gfcombine part.* - The file
partcontains the reconstructed secret