4.3BSD - /usr/man/cat1/enroll.0

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NAME
       xsend, xget, enroll - secret mail

SYNOPSIS
       xsend person
       xget
       enroll

DESCRIPTION
       These  commands  implement  a  secure communication channel; it is like
       mail(1), but no one can read the messages except the  intended  recipi‐
       ent.  The method embodies a public-key cryptosystem using knapsacks.

       To  receive  messages,  use enroll; it asks you for a password that you
       must subsequently quote in order to receive secret mail.

       To receive secret mail, use xget.  It  asks  for  your  password,  then
       gives you the messages.

       To  send secret mail, use xsend in the same manner as the ordinary mail
       command.  (However,  it  will  accept  only  one  target).   A  message
       announcing the receipt of secret mail is also sent by ordinary mail.

FILES
       /usr/spool/secretmail/*.key: keys
       /usr/spool/secretmail/*.[0-9]: messages

SEE ALSO
       mail (1)

BUGS
       It should be integrated with ordinary mail.  The announcement of secret
       mail makes traffic analysis possible.


7th Edition                     April 29, 1985                        XSEND(1)