This is some source code that does high-speed IDEA CFB encryption on
an 80x86.  The functions are not complete, in that they don't handle
blocks that are not a multiple of 8 bytes long, but it's a start, and
is included here for anybody to experiment with.  It is as efficient
as I could make it.  If USELODS is not set during assembly, a version
that uses the minimum number of instructions possible is produced.
USELODS, however, seems to be faster.  I have not tried it on a '486
yet.

Test.c is a test driver that times the code.  For real use, you'd need
to add key-unpacking code and code to handle odd-sized buffers.  The code
here is designed to be the middle part in a loop for encrypting an
arbitrary number of bytes:

xor leading odd bytes
IDEA encrypt
(xor 8 bytes and IDEA encrypt) as often as necessary
xor trailing odd bytes

It will probably become part of PGP some day.
-- 
	-Colin <colin@nyx.cs.du.edu>
