Hi Mauro,

Maverick Thunder wrote:

> I agree that there is no 100% secure thing but let me explain
> my point with another example: TV Cable digital signals,
> for e.g., DCT-700 decoder made by motorola used in several
> countries.
>
> Only very few people that works in Motorola knows the key
> pairs used but it is known that it uses 3DES algorithm. Well,
> there is too many people around the world trying to hack the
> encryption to see cable tv free and/or sell "tweaked"
> decoders but for now there is no success. Also you have
> access to millons and millons of rows alias packets you can
> analyze because cable company are sending them always in
> their transmition.

"no success": so their PR is working then. :-)

The millions of rows of cable data and the millions of blocks
of an encrypted volume are not the same as millions of rows of
database data in which a field was encrypted via (a typical)
UDF implementation. Until you understand the differences you
will not understand why the typical UDF approach is usually
much weaker (there are additional precautions possible when you
know what you need).

If you want to read about the smartcard technology used by pay-
TV and many other industries, and how to crack it, this book
makes excellent reading:
Security Engineering, by Ross Anderson
http://www.cl.cam.ac.uk/~rja14/book.html

If you are interested enough to read about how real encryption
actually works you could try:
Applied Cryptography, by Bruce Schneier
http://www.schneier.com/book-applied.html

It is much heavier going than the prior book but covers the
sort of stuff you need to understand before trying to write
your own encryption routines - even when using a proven
algorithm.

--
Geoff Worboys
Telesis Computing