DESexample

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

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

ENCRYPTION Original input:

(1) Apply IP:

0 1 1 1 0 1 0 0

(2) Apply f_Key1:

f_Key1(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:

(B) Add Key1:

0 0 0 0 0 1 1 1

(D) Apply P4:

1 1 1 0

f_Key1(0 1 1 1 0 1 0 0) = ((0 1 1 1) XOR (1 1 1 0) , (0 1 0 0)) =

(3) Apply SW:

0 1 0 0 1 0 0 1

(4) Apply f_Key2:

f_Key2(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:

(B) Add Key2:

0 0 1 0 1 0 0 1

(D) Apply P4:

0 0 1 0

f_Key2(0 1 0 0 1 0 0 1) = ((0 1 0 0) XOR (0 0 1 0) , (1 0 0 1)) =

(5) Apply IP^-1:

0 0 1 1 0 1 1 0

* Example by Laura Sanchis , Colgate University.