Public-domain DES commands, library and utilities by Phil Karn, KA9Q
This file last updated 21 Dec 1987

The makefile compiles everything and runs test data (from the NBS
certification suite) through DES.  Everything runs as-is under MS-DOS. 
For UNIX, change the name of the console in getpass.c.  For big-endian
machines like Pyramid and the 68000 (Macintosh, Sun, Amiga), comment out
the definition of LITTLE_ENDIAN in the makefile.  DEC VAXen and the
Intel 8086 family (IBM PC) are little-endian, so this definition should
be left in for them regardless of the operating system.  If you get the
byte order wrong, the test output in "certify" will say "ENCRYPT FAIL"
instead of "OK"; just change the flag and recompile.

The des executable (source in main.c) is a encrypt/decrypt filter
compatible with Sun's des command.  Included are uuencode/uudecode
utilities for encoding and decoding the binary ciphertext from des into
printable ASCII for secure transmission through mail systems.

Radlogin is an experimental program for secure login over insecure
channels (like packet radio).  It runs under Berkeley UNIX only.  Make
it the shell for a special, password-free login (e.g., "radio").  When
it starts the user will be asked his REAL login name, which is then
looked up in /etc/rkeys.  (This file must be protected since it contains
DES keys).  The time of day is then printed in hex as a challenge, and
the user must encrypt it using DES and his key and type the answer back. 
The user uses the program "descalc" to perform his local calculation. 
All this is very clumsy; at a minimum it requires Doubledos (net.exe in
one partition, descalc in the other) and manual retyping of the
challenge in plain and ciphertext form.  Ideally this should be part of
net.exe, invoked perhaps by a special telnet option after the user's
name is entered.  If the client telnet refuses the option, it sends an
ordinary password prompt; otherwise it does the authentication and
bypasses the password. 

The format of /etc/rkeys is as follows:

user_name<sp>DES_key_in_hex
karn 0123456789abcdef
n4hy fedcba987654321

This is all experimental, of course; improvements are most welcome.

Phil