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+---- Thread: Classical Encryption Tutorial (/showthread.php?tid=3065321)
Classical Encryption Tutorial - baymandernam - Dec 2, 2012
Hey all! Welcome to my Classical Encryption Tutorial!
There are many different types of classical encryptions, some of which include:
- Beale cipher
- Transposition ciphers
- ceasar cipher
- atbash cipher
- playfair cipher
- polyalphabetic substitution
- Columnar transposition
In this tutorial we will be focusing on the Columnar transposition, and the polyalphabetic substitution cipher. Lets get started
The Polyalphabetic cipher
This cipher is a simple substitution cipher which an alphabet that changes.
For example:
Original text: ABCDEFGHIJKLMNOPQRSTUVWXYZ
Cipher Alphabet 1:BCDEFGHIJKLMNOPQRSTUVWXYZA
Cipher Alphabet 2:DEFGHIJKLMNOPQRSTUVWXYZABC
as you can see, this cipher just increments the letters by a certain amount. Cipher 1 is incremented by 1 and cipher 2 is incremented by 3.Thus, "Hello World" In cipher 1 would be: IFMMP XPSME
To decode one of these ciphers one must know the amount each letter is incremented by, For example if I just game you: HNUMJW decrypting it would take a long time. However, if i told you that each letter was Incremented by +5 (goes forward A-Z 5 for each letter) then you would be able to tell me that HNUMJW translated to CIPHER.
In addition, Text can be encrypted more than once. For example, If I used +5,-3,+4 on the word "DEATH" It would translate to: JKGYM
This is so because:
DEATH + 5 = IJFYM
IJFYM - 3 = FGCVJ
FGCVJ + 4 = JKGYM
Challenge(answers at bottom of thread):
Translate This: URYYB JBEYQ the cipher is 14.
Translate This: SVCM
Columnar transposition cipher
The Columnar transposition cipher is a cipher that consists of writing the original text as a column and then separating each column:
For Example:
Original text: HELLO FRIEND
HELL
OFRI
END
HOE EFN LRD LI = HELLO FRIEND
This cipher is very strong when used with others such as the polyalphabetic cipher.
To decrypt one of these ciphers you need to put each line of text into a column:
HOE
H
O
E
EFN
E
F
N
LRD
L
R
D
LI
L
I
Final:
HELL
OFRI
END
HELLOFRIEND = HELLO FRIEND
Challenge(answers at bottom of thread):
Translate This: GNT OI OG DH
Translate This: IE LY OO VU
CONCLUSIONS
When used together ciphers can be a very powerful way of protecting data. For Example:
If I write "KILL THEM ALL" with the cipher of +4,columnar, + 2 I will get: QZG ONR RKR RS
In addition, If I encoded any word and didnt tell you what the cipher was, you would have a really tough time decoding it.
Challenges(answers at bottom of thread):
Translate This: SHW ZOC WW PZ encoded with: +14, columnar, -2, columnar
Translate This: KGJ JO CC VV encoded with +2,columnar
I hope you liked this tutorial, keep an eye out for new program releases and tutorials by me! Thanks!
CHALLENGE ANSWERS:
POLYALPHABETIC CIPHER:
CHALLENGE 1: HELLO WORLD
CHALLENGE 2: LOVE
COLUMNAL CIPHER:
CHALLENGE 1: GOOD NIGHT
CHALLENGE 2: I LOVE YOU
CUMULATIVE CHALLENGE:
CHALLENGE 1: HELLO WORLD
CHALLENGE 2: I HATE MATH