Create an S-Box

[drew99]

Someone is able to explain to me the construction and operation of the DES S-Box, which from n input bits input, produces an output of m bits, with m <n?

I found some material, but I can't understand it:
http://it.wikipedia.org/wiki/S-Box
http://en.wikipedia.org/wiki/DES_supplementary_material

Thanks in advance for your answers.

[LB]

Please don't create multiple threads. You already have one here:
http://www.cplusplus.com/forum/general/83489/

[drew99]

Yes, but someone considered it cross posting, so I re-opened it in order to obtain some advice rather than unuseful messages.

[LB]

The topic was not closed, someone just pointed out that you were spamming support sites with the same question. You can still use the same thread for discussion.

[meganewbie]

responding to original thread http://www.cplusplus.com/forum/general/83489/

[drew99]

If it isn't cross-posting, can someone remove "meganewbie" messages?
Then, can somebody explain me this part of the algorithm?
Thanks to all.