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SUPER ENCRYPTION & PERFECT ALGORITHMKriptografi - Week 6

Aisyatul Karima, 2012

Standar Kompetensi Pada akhir semester, mahasiswa menguasai pengetahuan, pengertian,

& pemahaman tentang teknik-teknik kriptografi. Selain itu mahasiswadiharapkan mampu mengimplementasikan salah satu teknik kriptografiuntuk mengamankan informasi yang akan dikirimkan melalui jaringan.

Mahasiswa menguasai langkah super enkripsi Mahasiswa menguasai teknik rahasia algoritma sempurna Mahasiswa mampu menyelesaikan soal teknik one time pad Mahasiswa mampu menganalisa teknik enigma rotor machine

Kompetensi Dasar

Contents

1

Secret Perfect Algorithm2

Enigma Rotor Machine

3

Super Encryption

5

One Time Pad

Super Enkripsi

Super Encryption is the concept that uses two ormore combination of substitution technique andcode permutation to get the strong algorithm. Step of super encryption : Encrypt the message with substitution technique The encode message / ciphertext encrypt again with

transposition technique

Super Enkripsi

Example : Plaintext :

Encryption process:• Use the substitution technique with the Caesar

algorithm which key = 6

• The encoded message = … ??

KENAIKAN HARGA BBM MEMBUAT RAKYAT KECIL MENDERITA

A B C D E F G H I J K L M N O P Q R S T U V W X Y ZG H I J K L M N O P Q R S T U V W X Y Z A B C D E F

Super Enkripsi• Use the transposition technique with permutation

diagonal technique which the key = 4

• The result = … ??? Super encryption is important and most used for making

the algorithm.

Q K T GO Q G TN G X MG H H SS K S HA G Z XG Q E GZ Q K IO R S KT J K XO Z G X

Secret Perfect Algorithm

Cryptography is sending the secure message tosender uses code to make the messageunknown by the third party. Based on the reason, need the algorithm which

guarantee the message although the messagemove to the third party.


For the preventive the cryptanalyst break themessage, the message will be sending doesn’tfall to the third party. The system which reach this subject is called by

perfect secrecy.


Example : The director of company, Mr.X will make the

decision on company stock. If make the buy decision, so increase the

company. If the decision is sell, so decrease thecompany.


Mr.X sending the decision using the publicnetwork. The message has been sent to the stockbroker is

ciphertext. The other choice can use two key, there are K1

and K2.

Key Buy SellK1 0 1K2 1 0


Based on the example Mr.X always send themessage use the same algorithm. The opportunitiesfor guessed is 100%. If use the different algorithm or use 2 algorithm on

sending message process, so the opportunities is50%.

One Time Pad

There is the strong encoding which unbreakable.It is One Time Pad (OTP) encoding. At first, OTP has been introduced by Gilbert

Vernam on 1st world war.

One Time Pad

OTP encoding is one of substitution variantmethod with provide the specific terms of thekeywords used. This method made from the character or random

letter ( random key / pad ) and therandomization does not use a specific formula.

One Time Pad

OTP encoding produce by summing /subtracting the plaintext for the key. Utilization the key is single use only. To decrypt the ciphertext through the add /

subtracting process the ciphertext with the keyas the reverse process.

One Time Pad

At first, the alphabet convert into the number 1until 26 with A = 1; B = 2; until Z = 26. In the computation, the algebra is the modulus

26 number. The strength of OTP encryption method is based

on the randomness of the key, so that the keythat used for the encryption process must bewell protected.

One Time Pad

Example : Random Key :

Plaintext :

Algorithm• Ciphertext = Plaintext + Key

FGHJV KVLIH POKNH BESAG VMHBK BLQML OPUTT EXDFJ MIKNY GQDXS EQOIK HYGFBMIUYW UIOVC FDWUM KJLOK BTYVG KJABH SVQCG NBCVG FSJFJ HOSHZ VBQNZ BXCMSGDUFO GWZMF IPMSA BNAPD QWMOC PAJSB MSGYQ KWNAY ZHALU

DUNIA TELAH SEMAKIN DATAR MAKA BELILAH TV LAYAR DATAR

One Time Pad

Encoding process add with the 26 modulus number

The Ciphertext = … ??

Key : F= 6 G= 7 H= 8 J=10 V=22 K=11 V=22 L=12 I= 9 H= 8 P=16 O=15 K=11Plaintext : D= 4 U=21 N=14 I= 9 A= 1 T=20 E= 5 L=12 A= 1 H= 8 S=19 E= 5 M=13Ciphertext : ....................................................................................................................


Enigma is the coding machine to deliver the secretmessage which relate with the strategic state message.

Enigma machine has been found by Arthur Scherbiusfrom German.

This machine originally used for commercial purposes But, based on the war need from German ( rezim Adolf

Hitler,Nazi ) so that this machine used as a strategic toolof war .


German uses this machine as the reliable tool to encryptthe secret message.

Based on that makes USA tries to snatch this machine topeek the secure message of Axis German (German,Italia, Japan).

This machine was brought by : Wehrmacth (army) Kriegsmarine ( navy ).

The name Enigma comes from Latin language“aenigma” it means puzzles.


Enigma machine has severalitems :

keyboard with 26 letter, Lamp board with 26 letter, 3 sets rotator wheel, a reflector and a plug board

• (the amount of rotator different ineach variant, the 3 raotator usedfor Enigma M3 variant )


Enigma machine has a way of working where when wetype the word / phrase on the keyboard then thissentence will be in the right reflector then randomized by3 existing Rotator, Rotator each have 26 contacts onboth sides.

Each contact on one side connected to a contact onanother side with a different rotators and arrangement ofletters between rotators in random formation.

For each letter which is pressed on the keyboard, theright wheel rotators are rotated one letter, produces adifferent mapping for existing connections inside.


The diagram of the working way of enigma machine :


A Rotator has one or more notches that causes the nextrotators will shift in one position.

It is produce the different code for each letter whichpressed on the keyboard.

Keyboard is consist of 26 buttons, it’s called A until Z. When the button is pressed, say letter Q, the rotator will

be rotate on one new position and the contact isconnected.


When a letter key is pressed, an electric currentwill flow in this machine which starting withpasses a plug board, then continue past the 3Rotor. Upon arriving at the Reflector, electric current

passes through 3 Rotator reversed subsequentlyforwarded to the plug board and then encryptedletters shown on the lights on. The rotator is rotate after the ciphertext is lights

on.

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