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Latest Articles

Encryption 2

Arrow Image How to decrypt a Substitution cypher while building an understanding on basics of cryptography.



////////////////////////////////////////////
Encryption 2 Article
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\
\' If spoilers exist, I\'d ask
\' that the admins ammend this article to
\' their approval rather than remove it.
\'
\' I only leave spoilers, because, it only
\' hurts the person who just uses it just to
\' complete the challenge without getting a
\' grasp on the material. Otherwise, spoilers
\' can help just as much as hints.
\'
\' Read, Learn, Apply
\' -Sent
////////////////////////////////////////////

Overview:
This is an excellent challenge for several reasons...
1. It provides a great example of a very basic cypher.
2. It gives those of you, whom are new to cryptology a foundation to build on.

I\'ll elaborate...

Tools:
PolyCrypt: http://tws.serveftp.org/hbh/tools/PolyCrypt.zip


Let\'s Begin:

Our solution in cyphered form which we are given:

05171606.05161220.16\'12.1810161118.0510.132005.1605.241313.22101220.100405;.05171606.05161220.
1612.1810161118.0510.0605241121.0409.241121.0617100405;.16.22072422142021.05171606!.


To an untrained eye this looks like scrambled numbers/puncuation. So to begin, we start a quick lesson
on basic cryptography.
->> The best cryptographers not only need to posess skills in mathematics, but language as well. <<-
This includes learning the most common: vowel, consonants, two-letter, three-letter words, articles.
Also, how sentences are constructed. Basically study the english language statistcally speaking.


In this article we will learn fundamental cryptography in Substitution Encryption.
You will also begin to notice many commonalities within our language.

To start, examine the cyphered string.
Notice how between each \".\" is an equal amount of numbers.
Now we\'re not sure what the solution really contains: numbers? letters? both? symbols? punctuation? ...
but we\'ll guess that the numbers mean something.

To figure that out, we need to somehow evaluate each letter in the alphabet to a number. EASY, since there\'s only 26.


Assigned Point Value System:
Screenshot: http://tws.serveftp.org/hbh/articles/encryption/pvs.JPG


No take a look back at the cyphered text. It begins with [05171606]. Well according to our point value system, there is no \"zeroth\" position, so let\'s

try splitting it up in two\'s.

We get [05 17 16 06]. This looks logical. So take each pair and write in the letter which corresponds with the number on our point system.

->> If you did it right, you\'d get [EQPF]

Now apply this to the entire cypher:

->> If done correctly, you\'d get: (POSSIBLE SPOILER! ADMINS PLEASE EDIT IF NOT SATISFIED)

(CAPITALIZED)
EQPF.EPLT.P\'L.RJPKR.EJ.MTE.PE.XMM.VJLT.JDE;.EQPF.EPLT.RJPKR.EJ.FEXKU.DI.XKU.FQJDE;.P.VGXVNTU.EQPF!.

(lowercase)
eqpf.eplt.p\'l.rjpkr.ej.mte.pe.xmm.vjlt.jde;.eqpf.eplt.pl.rjpkr.ej.fexku.di.xku.fqjde;.p.vgxvntu.eqpf!.

Use either one, I prefer looking at it capitalized, but at the end we\'ll have to change that.


OK! Halfway done! Now here\'s where a little bit of knowledge about language statistics comes in hand.

A substitution cypher is quite simply: A system in which taking an existing alphabet and assigning new letters to existing ones.

Lets now open PolyCrypt and select the \"Substitution\" tab.
Paste our new cypher in the top box.

Our goal is to figure out which letters correspond with the right letter to make this cypher readible.
I\'ll start you off.

The solution couldn\'t be a complete sentence with all these periods in it; It would just be fragments. So let\'s asign \".\" to a new letter.
In this case, lets assign it to \" \"; a space. I defintelly looks like it would apply.

In PolyCrypt, for each char you put into the Original alphabet text, you assign it a new char in the New alphabet text.

So put: (without quotes)
Orig alphabet: \".\"
New alphabet: \" \"

Click \"Decrypt\" and watch the new text appear with all \".\" changed to \" \".

Now...
The most common vowel used in the enlish language is \"E\".
The most common consonant is \"T\".
The most word is \"THE\".
There are so many statistics that can be recognized, and we never even realise it when speaking. It really is quite fascinating if do a little

research on it.

Anyway...
In the entire string, we see this [EQPF.EPLT] repeatedly.
So lets take an educated guess and say that:

E = T
&
Q = H (Most common letter found following a \"t\")

Fill in the new variables, and decrypt!

Screenshot: http://tws.serveftp.org/hbh/articles/encryption/enc2_2.JPG


Now try to finish the rest of this challenge using logic by examining the cryptic words.
To solve the challenge, capitalization and punctuation must be correct.


Good Luck. Hope this helped.
Comment if you\'d like; I\'d like to write more for HBH.

-Sent

Comments

TWS_Sentinelon August 30 2006 - 19:43:29
Sorry if the screenshots didn't work for you. I had switch OS's, but the server is up on both now so should work.
keiran420on August 30 2006 - 23:10:23
we already have articles on this, y not do an articleon one there aint 1 for, like enc 3?
TWS_Sentinelon August 30 2006 - 23:47:00
Will do, once I continue the encryption section ... trying to finish up the last two app challenges first.
sevenMSon August 31 2006 - 09:16:14
GREAT one.. clearly tutorial..
What_A_Legendon August 31 2006 - 13:53:14
wow i wish this article was about when i was wokring on the encryption great work Pfft
-The_Flash-on September 01 2006 - 16:01:59
Best tutorial... other than my encryption of course xD lies *sigh*
JohnDoeon November 04 2006 - 12:50:30
wicked man, the right info i needed for this challenge Wink
untraced_shadowon November 12 2006 - 04:44:21
Great it got me started in he right direction.Pfft
hacker_jacobon November 29 2006 - 19:48:50
THAT WAS AWSOME, NICE ARTICLE
cainamon December 19 2006 - 07:03:22
Very good job!!!:ninja:
ARCANE_UNDERDOGon February 19 2007 - 04:52:49
great job buddy actually i decrypted it up to [EQPF......] but was confused due to the dots
8i11yb0bon June 12 2007 - 03:46:21
i thought it was a smart idea for you to include a short history lesson in this tutorial, because its very helpful Smile a few years ago i taught myself to read braille using the same idea you had (most common word- the, vowel- e...etc.) also the only words that are one letter are "a" and "I"... so it elped to know that
HackingForceon July 18 2007 - 20:18:42
Awesome article, great Job!, LOVE it!Shock Rated Awesome
Ayr4on July 24 2007 - 22:42:27
Wery good article...tho i havent managed to complete it yet:/
KANOon August 31 2007 - 19:46:43
Loved it. Although it didn't accept my answer first time. Great article though.
nooberon October 28 2007 - 01:58:21
is there a decrypter that shows the letter you changed in a diffrent color or something? makes it hard when you cant tell if the letter on the bottom is a decryted one or undecrypted with out looking back and forth
dork5002002on December 11 2007 - 17:56:59
I noticed an error in one of your text strings. Your capitalized and lowercase strings are not the same. Your capitalized one is missing a PL
dork5002002on December 11 2007 - 17:57:11
I noticed an error in one of your text strings. Your capitalized and lowercase strings are not the same. Your capitalized one is missing a PL
loxaXcrackeron December 26 2007 - 23:44:55
the images don't work... but the article is awesome!! Grin
Syntaxeon May 20 2008 - 01:02:25
Nice article! =) and btw, if the host of the PolyCrypt.zip file is down, you may use additional mirror like http://files.crac. . .ycrypt.zip
jelmeron September 09 2008 - 01:20:54
links are down mate :angry:
77mod77on January 22 2010 - 16:31:01
B)B)B)B)B)B)B)B)B)B)
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