Which is more secure -- FHSS or DSSS?

[Green Xenon]

Hi:

 

Which method of radio transmission/reception for wireless computers is more secure -- Frequency-Hopping Spread Spectrum or Direct-Sequence Spread Spectrum?

 

I believe the former is more secure than the latter because it does not constantly remain on the same frequencies. Am I right?

 

 

Thanks,

 

Green

[StringJunky]

I found this which seems to support your thought:

 

" 7.- Security

The issue: Protecting the transmission against eavesdropping

IEEE 802.11 compliant DSSS systems use one well known spreading sequence of 11 chips, and

can modulate one of the 14 channel defined in the standard. As the sequence used is apriori

known, the carrier frequency is fixed for a given system, and the number of possible frequencies is

limited, it would be quite easy for a listener to “tune in” on the DSSS transmission. Message

protection should be achieved by encrypting the data. This option increases the price of the

product, while lowering its performance, because of the processing power needed for the

encryption process.

In FHSS, the frequencies to be used in the hopping sequence may be selected by the user. In the

unlicensed band, any group of 26 frequencies or more (out of the 79 available) is legal. To “tune

in”, a listener should know the number of frequencies selected in the system, the actual

frequencies, the hopping sequence, as well as the dwell time! The FHSS modulation acts as a

layer 1 encryption process. There could be no need for application level encryption!"

 

http://www.sorin-schwartz.com/white_papers/fhvsds.pdf