cst - cryptographical file split.

cst allows to split (or share) "secret" files, like private keys, into number of equal parts. After that, secret can only be recovered by collecting all parts together. If any of this parts is lost, the secret is lost too.

cst is based on idea of one-time pad's (OTP). Security of cst is heavily depends on strong pseudo-random number generator, so look for good random(4) implementation, or any other useful entropy pool.

Example of splitting/compiling private key

Splitting

  $openssl genrsa -out the_secret

  $cst -S -n 2 -e /dev/random the_secret
  generating 493 byte key-parts, this can take a while.
  generating key-part 1.
  generating key-part 2 (hashing keys).
	

Restoring

  $cst -C -O the_secret key-part-*
  hashing keys.
	

Download