A simple (2, n) secret-sharing scheme that allows the user to split a secret into n shares, and require at least two shares to recover the secret.
This works by generating a line which has the secret as the y-intercept. The "shares" are then generated as random points on this line. With one share it is impossible to know the line, but with any two points one can recover the line and thus recover the secret.
Split a secret in secret.txt into 5 shares:
./twon.py split secret.txt 5
Recover a secret from the first two shares (lines) in shares.txt:
./twon.py recover shares.txt
To read from stdin, use - as a filename.