Basics of the routine
It is a Feistel type routine although addition and subtraction are used as the
reversible operators rather than XOR. The routine relies on the alternate use of
XOR and ADD to provide nonlinearity. A dual shift causes all bits of the key
and data to be mixed repeatedly.
The number of rounds before a single bit change of the data or key has spread
very close to 32 is at most six, so that sixteen cycles may suffice and we suggest
32.
The key is set at 128 bits as this is enough to prevent simple search techniques
being effective.
This type of algorithm can replace DES in software, and is short enough to
write into almost any program on any computer.感觉作者当时想用这个取代DES