makekey - generate encryption key
makekey improves the usefulness of encryption schemes depending on a
key by increasing the amount of time required to search the key space.
It reads 10 bytes from its standard input and writes 13 bytes on its
standard output. The output depends on the input in a way intended to
be difficult to compute (i.e., to require a substantial fraction of a
The first eight input bytes (the input key) can be arbitrary ASCII
characters. The last two (the salt) are best chosen from the set of
digits, ., /, and uppercase and lowercase letters. The salt
characters are repeated as the first two characters of the output.
The remaining 11 output characters are chosen from the same set as the
salt and constitute the output key.
The transformation performed is essentially the following: the salt is
used to select one of 4,096 cryptographic machines all based on the
National Bureau of Standards DES algorithm, but broken in 4,096
different ways. Using the input key as key, a constant string is fed
into the machine and recirculated a number of times. The 64 bits that
come out are distributed into the 66 output key bits in the result.
makekey is intended for programs that perform encryption (e.g., ed(1)
and crypt(1)). Usually, its input and output will be pipes.
crypt(1), ed(1), passwd(4).
Hewlett-Packard Company - 1 - HP-UX Release 11i: November 2000