Contents

### Main Difference

The difference between DED and AES is that DES is data encryption standard that is plaintext block divided into two halves before main algorithm start whereas AES is advanced encryption standard in which entire block is processed to obtain the ciphertext.

### DES (Data Encryption Standard) vs. AES (Advanced Encryption Standard)

There are types of a symmetric block cipher, two main types of symmetric block cipher are DES and AES. DES is data encryption standard, and AES is advances encryption standard. There was some disadvantage in DES that was covered by AES. This is why is known as advanced encryption standard. DES is less secure because it has smaller key size this why AES was introduced. AES was introduced by National Institute of Standard and Technology. DES that is data encryption standard that was introduced by National Institute of Standard and Technology on 1977. DES is a symmetric key block cipher. DES is divided into two halves. This is why it is based on a feistel structure. DES produce 64 bit ciphertext by taking 64 bit plain text and 56 bit key. In DES 64 bit plaintext goes in initial permutation which rearranges the bits to get the complete 64 bit permuted input. 64 bit permuted input is then divided into two halves that becomes 32 bit. AES is an advanced encryption standard that is a symmetric key block cipher. After DES, AES was published in 2001 by National Institute of Standard and technology. The main purpose was to replace DES with AES as it takes 128 bit plaintext and 128 bit secret key which together forms a 128 bit block.

If we talk about the main difference, then the main difference between DED and AES is that DED is data encryption standard that is plaintext block divided into two halves before main algorithm start whereas AES is advanced encryption standard in which entire block is processed to obtain the ciphertext. This partition undergoes, again and again, this is what DES does. A final permutation is done after sixteen round. After sixteen round 64 bit ciphertext is obtained. There are functions of every round. In Expansion permutation 32 bit right portion is expanded to form 48 bit right portion. In Xor 48 bit subkey obtained from the 56 bit key. In S box function 48 bit is reduced to 32 bit. AES form 4*4 square matrix that undergoes an initial transformation. There are 16 steps in DES, but there are just 10 steps in AES. Subbytes uses S box by which it performs byte by byte substitution. In shift row rows of the matrix are shifted. In mix columns, columns are shuffled from right to left.

### Comparison Chart

### What is DES?

DES that is data encryption standard that was introduced by National Institute of Standard and Technology on 1977. DES is a symmetric key block cipher. DES is divided into two halves this is why it is based on feistel structure. DES produce 64 bit ciphertext by taking 64 bit plain text and 56 bit key. In DES 64 bit plaintext goes in initial permutation which rearranges the bits to get the complete 64 bit permuted input. 64 bit permuted input is then divided into two halves that becomes 32 bit. This partition undergoes, again and again, this is what DES does. A final permutation is done after sixteen round. After sixteen round 64 bit ciphertext is obtained. There are functions of every round. In Expansion permutation 32 bit right portion is expanded to form 48 bit right portion. In Xor 48 bit subkey obtained from the 56 bit key. In S box function 48 bit is reduced to 32 bit.

### What is AES?

AES is an advanced encryption standard that is a symmetric key block cipher. After DES, AES was published in 2001 by National Institute of Standard and technology. The main purpose was to replace DES with AES as it takes 128 bit plaintext and 128 bit secret key which together forms a 128 bit block. AES form 4*4 square matrix that undergoes an initial transformation. There are 16 steps in DES, but there are just 10 steps in AES. Subbytes uses S box by which it performs byte by byte substitution. In shift row rows of the matrix are shifted. In mix columns, columns are shuffled from right to left.

### Key Differences

- DES is data encryption standard that is plaintext block divided into two halves before the main algorithm start whereas AES is an advanced encryption standard in which the entire block is processed to obtain the ciphertext.
- DES work on feistel cipher principle whereas AES work on substitution permutation principle
- DES has 16 rounds whereas AES has 10 rounds.
- DES has a smaller key and less security whereas AES has a larger key and higher security