Data Encryption Standard - Step by Step

AARRRGH

Hello

I'm currently reading this document -

http://www.nic.funet.fi/pub/crypt/mirrors/ftp.dsi.unimi.it/docs/des-how-to.txt

- to understand DES step by step.

It's still a bit complicated for me

Do any of you know an even simplier step by step guide to how this algorithm works?

Thanks

Martyr

The wiki entry on it isn't bad..do you just want to implement it?
perhaps studying other peoples source code while reading the document would help.
FIPS-46-3 is the main documentation released by NIST.

the document you reference would probably make a little more sense if its design decisions had been revealed by its chief architects, IBM/NSA.

AARRRGH

Thanks for your reply.

Well what I'm looking for I guess is a plain English step by step explanation of the algorithm.

For example...

You start with 64 bits.
The least significant bit is stripped off each byte.
You split the remaining 56 bits into two 28 bit halves.
You rearrange half one like this:

etc etc.

I've found lots of explanations but they're written from the perspective of a maths teacher...

probe

dublindude wrote: »

Thanks for your reply.

Well what I'm looking for I guess is a plain English step by step explanation of the algorithm.

For example...

You start with 64 bits.
The least significant bit is stripped off each byte.
You split the remaining 56 bits into two 28 bit halves.
You rearrange half one like this:

etc etc.

I've found lots of explanations but they're written from the perspective of a maths teacher...

I presume that you are studying it from an academic perspective, (ie as a piece of history). DES has been broken over and over, and is 1980s technology.

.probe

Cantab.

3DES is quite insecure.

Can be cracked using the Copacobana in around 6 days (2007).

AARRRGH

Got it.

http://www.aci.net/Kalliste/des.htm

Very simple to understand.

PS I'm aware DES is old technology etc., but it's an important encryption algorithm and IMO worth understanding if you're interested in cryptology.