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encryption and authentication are outlined in the following URLs. Many computer soft-
ware libraries contain subroutines to support secure communications. If the data stream
moves too fast for software encryption, hardware chips are available that can encrypt
the information faster. Popular encryption standards are listed at www.cs.auckland
.ac.nz/ pgut001/links/standards.html and include the Data Encryption Standard
™
(DES), RSA, and Pretty Good Privacy (PGP) .
DATA ENCRYPTION STANDARD (DES)
DES has won the backing of the government and is present in many commercial trans-
actions today. The calculation methods are fairly straightforward and chipsets are avail-
able for high-speed implementations. Further information on DES can be found at the
following URLs:

http://axion.physics.ubc.ca/crypt.html#aDES
www.tropsoft.com/strongenc/des.htm
www.tropsoft.com/strongenc/des3.htm

RSA

RSA security is based on the fact that it’s very difficult to factor large numbers. If a
hacker could factor a huge number in less than a few years, the hacker could break into
the communications link. So far, it’s proven too difficult (see www.rsasecurity.com/).

PRETTY GOOD PRIVACY (PGP)™
™
PGP security is also based on difficult mathematical calculations and is offered in sev-
eral versions, as detailed at the following sites:

www.pgp.com/
www.neiu.edu/ ncaftori/PGP.htm
www.scramdisk.clara.net/pgpfaq.html
Dos attacks happen when a determined hacker sends packets to the robot that it can-
not handle. Some DoS attacks involve sending packets with an illegal data structure;
other DoS attacks involve sending too many packets so the channel gets clogged up. Be
sure your software can handle packets with illegal structures, and consider testing it
with simulated DoS attack data. Some web sites speak to this issue, such as www.
geocities.com/solarsistem/gif/docs/dos.htm and www-arc.com/sara/coe/distributed_
denial_of_service.html