🚀 go-pugleaf

jmount+@CS.CMU.EDU (John Mount) writes:
[ previous posters' discussing UNIX crypt deleted ]
> 
> No I don't think you understand how crypt works (or have it confused with
> the unix password encryption scheme, which is intended to be one way).  Crypt
> doesn't use DES (see below man page), it is a wimpy Enigma machine.  DES 
> IS invertible (ie. people do decrypt DES messages).
>
[ man page on crypt deleted, except ...] 
> 
> SEE ALSO
>      ed(1), makekey(8)
> 

Crypt DOES use DES through makekey(). The gist of the process goes
something like this:

 1) Pass a seed and user password to makekey() and get
    back a DES'sed password.
 2) Using the new, improved password create the rotor assembly
    for the translational encryption.
 3) Read a plaintext char from stdin and translate through rotor
 4) Spit out cyphertext char to stdout, advance rotor, do 3 till EOD.

To decrypt, the rotor "assembly" is reversed, so you are effectively
using the previous cyphertext as the plaintext in the above process.

[sensing impending doom, our author puts on a cancer causing asbestos suit]
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