## EXAMPLE  OF  USING  SIMPLIFIED  DES*

Input:

 1 0 1 0 0 1 0 1

Key:

 0 0 1 0 0 1 0 1 1 1

Generating KEY1

Original key :

 0 0 1 0 0 1 0 1 1 1

After applying (A):

 1 0 0 0 0 1 0 1 1 1

After applying (B):

 0 0 0 0 1 0 1 1 1 1

After applying (C):

KEY1

 0 0 1 0 1 1 1 1

Generating KEY2

Original key :

 0 0 1 0 0 1 0 1 1 1

After applying (A):

 1 0 0 0 0 1 0 1 1 1

After applying (B):

 0 0 0 0 1 0 1 1 1 1

After applying (D):

 0 0 1 0 0 1 1 1 0 1

After applying (C):

KEY2

 1 1 1 0 1 0 1 0

ENCRYPTION

Original input:

 1 0 1 0 0 1 0 1

(1)  Apply IP:

 0 1 1 1 0 1 0 0

(2)  Apply  FKey1:

FKey1(0 1 1 1 0 1 0 0) = ((0 1 1 1) XOR  f(0 1 0 0, Key1), (0 1 0 0))

To compute  f(0 1 0 0 , Key1):

(A)  Apply E/P:
 0 0 1 0 1 0 0 0

 0 0 0 0 0 1 1 1

(C)  Pass left 4 bits through S0 and right four bits through S1:
 0 1 1 1

(D)  Apply P4:
 1 1 1 0

FKey1(0 1 1 1 0 1 0 0) = ((0 1 1 1)  XOR  (1 1 1 0) , (0 1 0 0)) =
 1 0 0 1 0 1 0 0

(3)  Apply SW:

 0 1 0 0 1 0 0 1

(4)  Apply  FKey2:

FKey2(0 1 0 0 1 0 0 1) = ((0 1 0 0) XOR  f(1 0 0 1 , Key2), (1 0 0 1))

To compute  f(1 0 0 1 , Key2):

(A)  Apply E/P:
 1 1 0 0 0 0 1 1

 0 0 1 0 1 0 0 1

(C)  Pass left 4 bits through S0 and right four bits through S1:
 0 0 1 0

(D)  Apply P4:
 0 0 1 0

FKey2(0 1 0 0 1 0 0 1) = ((0 1 0 0)  XOR  (0 0 1 0) , (1 0 0 1)) =
 0 1 1 0 1 0 0 1

(5)  Apply IP-1:

 0 0 1 1 0 1 1 0
*Example by Laura Sanchis, Colgate University.