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Piss Issue 40
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- P.I.S.S. Philez Number 40 =
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- CRYPTOGRAPHY - an intro =
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- by PhrostByte =
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BASIC (GLR)
crypto is bein used more and more these days 'cause ppl want privacy.
well, in this phile and maybe a few to come, i'll talk about a few general
types of crypto, including a few examples.
1st let's look at one of the most basic types of crypto, general letter replacement.
GLR werks like it sounds. so i won't insult your intellegence. instead i'll skip to an example.
message: slap mah fro
alphabet key: fghijklmnopqrstuvwxyzabcde
encrypted message: xqfu rfm kwt
as you can see, this is very ez to break using general logic, such as:
the most common 2 vowels: E A
most common consonants: R S T L N
A common type of GLR is reverse alphabetic encryption.
where 'a' corresponds to 'z' and 'y' to 'b' etc.......
but this is probably the most simple type. let's move on to matrices.
MATRICES
matrices, like magic, make encryption many times stronger than GLR does. in fact, it is magic...
and if you believe that load of bullshit then you MUST reformat your hard drive now...
anyway, a basic matrix encryption type is polybius. it uses a 5x5 matrix as shown below.
1 2 3 4 5
#------------------
|
1 | a b c d e
|
2 | f g h ij k
|
3 | l m n o p
|
4 | q r s t u
|
5 | v w x y x
notice the 'i' and the 'j' share the same square and if you know basic math, you can figure out
why.
so you get number coordinates for the letters. but for more secure encryption, you need different
matrices. I would also now like to introduce keys.
vigenere encryption:
this is based on the following matrix:
ABCDEFGHIJKLMNOPQRSTUVWXYZ
BCDEFGHIJKLMNOPQRSTUVWXYZA
CDEFGHIJKLMNOPQRSTUVWXYZAB
DEFGHIJKLMNOPQRSTUVWXYZABC
EFGHIJKLMNOPQRSTUVWXYZABCD
FGHIJKLMNOPQRSTUVWXYZABCDE
GHIJKLMNOPQRSTUVWXYZABCDEF
HIJKLMNOPQRSTUVWXYZABCDEFG
IJKLMNOPQRSTUVWXYZABCDEFGH
JKLMNOPQRSTUVWXYZABCDEFGHI
KLMNOPQRSTUVWXYZABCDEFGHIJ
LMNOPQRSTUVWXYZABCDEFGHIJK
MNOPQRSTUVWXYZABCDEFGHIJKL
NOPQRSTUVWXYZABCDEFGHIJKLM
OPQRSTUVWXYZABCDEFGHIJKLMN
PQRSTUVWXYZABCDEFGHIJKLMNO
QRSTUVWXYZABCDEFGHIJKLMNOP
RSTUVWXYZABCDEFGHIJKLMNOPQ
STUVWXYZABCDEFGHIJKLMNOPQR
TUVWXYZABCDEFGHIJKLMNOPQRS
UVWXYZABCDEFGHIJKLMNOPQRST
VWXYZABCDEFGHIJKLMNOPQRSTU
WXYZABCDEFGHIJKLMNOPQRSTUV
XYZABCDEFGHIJKLMNOPQRSTUVW
YZABCDEFGHIJKLMNOPQRSTUVWX
ZABCDEFGHIJKLMNOPQRSTUVWXY
next we take the message:
piss roxxors yer fro
and come up with a key:
defenestrator
then we do this:
piss roxxors yer fro
defe nestrat ord efe
now we have the coordinates in the graph of the cipher text. after that, we get the cipher using
(column, row) substitution.
(p,d) (i,e) (s,f) (s,e) (r,n) (o,e) (x,s) (x,t) (o,r) (r,a) (s,t) (y,o) (e,r) (r,d) (f,e) (r,f) (o,e)
smxw espqfrl mvu jws
PLAYFAIR
playfair is actually one of my faves as far as simple matrix encryption goes. first you come up
with a key.
PHROSTBYTE
then you take out double letters:
PHROSTBYE
then you add all the missing alphabet letters to the matrix (except 'j' which is paired with 'i':
PHROSTBYE
GXLNDUIQA
WZCMVFK--
now you make another matrix (5x5) by reading the columns:
P G W H X
Z R L C O
N M S D V
T U F B IJ
K Y Q E A
now that we have our key matrix, we can encipher a message
message: get cantaloop script
you find the letters for the encrypted text by first splitting it into 2 letter pairs:
ge tc an ta lo op sc ri pt
then you use the pattern of (row,column) (column,row) to find the cipher text.
row 'g' column 'e' = Y
column 't' row 'c' = Z
row 'a' column 'n' = K
column 't' row 'a' = K
row 'l' column 'o' = Z (note if two letters are in the same row, you take the letter to the right, and the matrix wraps around so we get 'Z')
column 'o' row 'p' = X
row 's' column 'c' = D
column 'r' row 'i' = U
row 'p' column 't' = K (likewise, if 2 letters are in the same column, take the letter below)
so the encrypted message is......
YZKKZXDUK
now if you really wanted to make the code hard to crack, you could encode the coded message again
using playfair or another type of encoding. i think it's useful to use a GLR on the code, then
run it backwards and reencode it with playfair or another type.
now we get into very secure stuph.
GEOMETRIC ENCODING
This can be done in several ways. The way i would generally use it is to take an already
encoded message and do some GLR. Then put it in a matrix like this (let's say we use the message
"sacrifice your gerbil and submit to the fro gods they will straighten your crooked fro"):
s a c r i f i c e
y o u r g e r b i
l a n d s u b m i
t t o t h e f r o
g o d s t h e y w
i l l s t r a i g
h t e n y o u r c
r o o k e d f r o
then you make a geometric key....which is basically a pattern you run through the matrix to
include the entire message.
I could go diagonally:
saycolruatirntgfgdooiiestdlhcruhsltrebbetseoimfhtnoirerykoyaoewiudgrfcro
or any number of the hundreds of millions of ways.
this is an excellent way to encrypt when used in conjunction with other methods.
now go write a proggie that encrypts and decrypts. remember, be creative, try new things, and
make damn sure that if you write an encryption proggie it werks both ways before you destribute
it to yer frendz dammit (assuming you have frendz).
cya in hell.
PhrostByte
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[Phrosty writes! About time. Nice ascii, he knows I can't draw worth
shit. Lots of hidden (not really) messages in here. Hope he will write
some software using this, because there's no way in hell I will. -Def]
----------------------------------------------------------------------
PISS - People into Serious Shit
Founderz - Defenestrator, PhrostByte
Memberz -
Author Parselon
Wu Forever
kQs
CGibbons
Extinction
Faekon/Homarid
Grench
Greenseed
Tim 121
Rhodekyll
Dial Tone
Psycho Phreak
Djdude
Circular Reclusion
Havok Luther
AT2Screech
Contributors-
Sameer Ketkar
Phantom Operator
PISS, the author, and anyone else does not take responsibility for what
you do with the stuph contained in this phile. If you get busted,
don't cry to us. We don't care.
Want more stuph? Go to http://piss.home.ml.org
The site will change as soon as Phantom Operator puts up his damn domain.
E-mail the group at davematthews@rocketmail.com
(C) Copyright 1997 PISS Publications and also copyrighted by the author.
This file may be posted freely as long as this notice stays on the end.
All rights reserved.
