MESSAGE
| DATE | 2016-05-02 |
| FROM | Ruben Safir
|
| SUBJECT | Re: [Hangout-NYLXS] Basic Cyprtography
|
On 05/02/2016 05:44 AM, Rick Moen wrote:
> Quoting Ruben Safir (mrbrklyn-at-panix.com):
>
>> this is what you sound like at 3AM Pacific time
>
> I could convert the rot13 to rot26 for you. My understanding is that
> it's twice as secure a cipher!
> _______________________________________________
> hangout mailing list
> hangout-at-nylxs.com
> http://www.nylxs.com/
>
Textbook on Block Ciphers:
Instead, block ciphers typically use functions that simulate randomly
permuted tables. An example (adapted from [Kaufman 1995]) of such a
function for k = 64 bits is shown in Figure 8.5. The function first
breaks a 64-bit block into 8 chunks, with each chunk consisting of 8
bits. Each 8-bit chunk is processed by an 8-bit to 8-bit table, which is
of manageable size. For example, the first chunk is processed by
the table denoted by T 1. Next, the 8 output chunks are reassembled into
a 64-bit block. The positions of the 64 bits in the block are then
scrambled (permuted) to produce a 64-bit output. This output is fed back
to the 64-bit input, where another cycle begins. After n such cycles,
the function provides a 64-bit block of ciphertext.
The purpose of the rounds is to make each input bit affect most (if not
all) of the final output bits. (If only one round were used, a given
input bit would affect only 8 of the 64 output bits.) The key for this
block cipher algorithm would be the eight permutation tables (assuming
the scramble function is publicly known).
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Is this an 8 bit table or a table of 2^8 applied to 8 bits.
http://www.nylxs.com/docs/textbooks/com_net.pdf
Cpter 8 Cipher block chaining..
--
So many immigrant groups have swept through our town
that Brooklyn, like Atlantis, reaches mythological
proportions in the mind of the world - RI Safir 1998
http://www.mrbrklyn.com
DRM is THEFT - We are the STAKEHOLDERS - RI Safir 2002
http://www.nylxs.com - Leadership Development in Free Software
http://www2.mrbrklyn.com/resources - Unpublished Archive
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http://www.brooklyn-living.com
Being so tracked is for FARM ANIMALS and and extermination camps,
but incompatible with living as a free human being. -RI Safir 2013
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