keyxor

Keyxor Söze

keyxor is a tool for secret sharing by splitting up a key into multiple pieces which need to be XOR'd together to get the original private key. A key XOR, if you will.

Status: Alpha. Implementation is there, needs audit.

Design

Given an input key, generate N-1 cryptographically secure random values of the key size. XOR the random values against the private key, producing N components (not including the original key) which need to be XOR'd together to produce the original key.

Usage

$ keyxor --help
Usage:
  keyxor [OPTIONS] [merge | split]

Application Options:
  -v, --verbose  Show verbose logging.
      --version  Print version and exit.
      --base32   Encode output and decode input as Base32

Help Options:
  -h, --help     Show this help message

Available commands:
  merge  Merge secure pieces into the original secret
  split  Split a secret into secure pieces

Example:
  $ echo "hunter2" > secret.txt
  $ keyxor split secret.txt --num=3
  $ ls secret.*
  secret.txt   secret.txt.1   secret.txt.2   secret.txt.3
  $ cat secret.txt.{1,2,3}
  [... random symbols]
  $ keyxor merge secret.txt.{1,2,3}
  hunter2

# Use your fav key generator!
$ ssh-keygen -f key
$ ls
key            key.pub

# Split the private key into 3 pieces
$ keyxor split --num=3 ./key
$ ls
key            key.1            key.2            key.3            key.pub

# Merge the 3 pieces back together
$ keyxor merge ./key.* > key.new
$ shasum key key.new
<same hash>  key
<same hash>  key.new

Is it any good?

It's a very simple tool that doesn't do much heavy lifting but it's very handy if you want to require exactly N secret key components to decrypt something.

This can be applied to a symmetric key or the private half of a public-private keypair, depending on the security model you're trying to achieve.

Keyxor does not support M of N secret sharing, like Shamir's Secret Sharing scheme. Keyxor uses a trivial method which only works for M=N. You need all the pieces to get the original key. Simple is good, right?

Audit?

Please do. The meat is inside soze/soze.go.

• @mveytsman, after an informal audit on c2d26906:

  There's not enough code here to be interesting. ¯\_(ツ)_/¯

License

MIT