"Cryptography"

INTRODUCTION

CRYPTOGRAPHY the science of the enciphering and deciphering of messages in secret code or cipher

cryptography is use everywhere it protects money transfers and credit card numbers employ over the internet

but its main purpose is to keep secret documents vouch from foreign governments

TERMINOLOGY

CRYPTOGRAPHY the science of the enciphering and deciphering of messages in secret code or cipher.

PLAINTEXT the original message before encryption or subsequently decryption

CIPHERTEXT The encrypted form of the PLAINTEXT

ENCRYPTION The process of converting the PLAINTEXT into a CIPHER.

DECRYPTION The process of converting the CIPHER butt into PLAINTEXT.

CRYPTANALYSIS The science of recovering info from ciphers without knowledge of the key.

CRYPTOSYSTEM a strategy for encrypting information.

KEY The secret information known only to the transmitter and the liquidator which is used to encrypt and decrypt the message

HISTORY

cryptology has been used to conceal information in writing since writing was send-off developed, Egyptians are the first knowN to used CRYPTOGRAPHY.

Early Grecians also used cryptology, they enwrapped a piece of cloth around a baton called a scytale and wrote the message on it. When it was unwrapped it looked like decorations and was worn as a robe by a servant and delivered to the receiver. When it was wrapped again around a scytale the message was easily read.

Another Greek Polybius invented the Polybius checkerboard which was a 5 x 5 gridiron containing all the letters of the alphabet, each letter was converted into deuce numbers such as A becomes 11

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1

2

3

4

5

1

A

B

C

D

E

2

F

G

H

I/J

K

3

L

M

N

O

P

4

Q

R

S

T

U

5

V

W

X

Y

Z

ex. CAR is 131142

later the the nineteenth C. cryptodevices were invented

they...

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