makekey(ADM)                    19 June 1992                    makekey(ADM)


 Name

    makekey - generate an encryption key

 Syntax

    /usr/lib/makekey

 Description

    makekey improves the usefulness of encryption schemes 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 out-
    put depends on the input in a way that is intended to be difficult to
    compute (i.e., to require a substantial fraction of a second).

    The first 8 input bytes (the ``input key'') can be arbitrary ASCII char-
    acters.  The last 2 input bytes (the ``salt'') are best chosen from the
    set of digits, dot ``.'', slash ``\'', and uppercase and lowercase
    letters.  The salt characters are repeated as the first 2 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 the key, a constant string is fed into the
    machine and recirculated.  The 64 bits that come out are distributed into
    the 66 output key bits in the result.

 See also

    passwd(FP)