Symmetric Key Encryption

Symmetric encryption is a type of encryption where only one key (a secret key) is used to both encrypt and decrypt electronic data.

Steps for creating Cipher block and pattern

Cipher

Plain text abcdefghijklmnopqrstuvwxyz

Now for example if you choose key 5 and key 18 and key 3 and key 6, the key 1 and 2 would start from d and g

Key 1 fghijklmnopqrstuvwxyzabcde

Key 2 stuvwxyzabcdefghijklmnopqr

Pattern

21221

Plain text abcdefghijklmnopqrstuvwxyz

Key 1 fghijklmnopqrstuvwxyzabcde

Key 2 stuvwxyzabcdefghijklmnopqr

Now suppose you have a message "ENCRYPTION IS FUN"

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

Z

F

G

H

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M

N

O

P

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S

T

U

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W

X

Y

Z

A

B

C

D

E

S

T

U

V

W

X

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Z

A

B

C

D

E

F

G

H

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J

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N

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So what you need to do here is take the first letter of your message in plain text, so here it is E, now go to the Key 2 and see what row it falls on, here we can see it falls on W now for N go to Key 1 and see what row it falls on.

ENCRYPTION IS FUN
WSUJDIYAGS AK XMS

The pattern here was 21221 that means first you need to check the second key then first key then second key (2) then first key H

How emails are encrypted is because of programs. The programs code the product.

We need to send the receiver the cipher to decode and there comes the security problem, hence you see numerous cryptography evolution.

The disadvantage of any encryption is how to transport the cipher key.