Question

Data Encryption Standard (DES) is insecure because of the size of the encryption key. Advanced Encryption Standard (AES) is the current NIST standard for encryption and is used in most applications. Explain the differences between the following concepts as they apply to both algorithms.

Concept	DES	AES
S-BOX
Permutation
Key Size

Answer 1

Q Data Encryption Standard (DES) is insecure because of the size of the encryption key. Advanced Encryption Standard (AES) is the current NIST standard for encryption and is used in most applications. Explain the differences between the following concepts as they apply to both algorithms.

Ans: Firstly let's know about the Data Encryption Standard (DES) and the Advanced Encryption Standard (AES) .

DES: It stands for the Data Encryption Standard.It is an algorithm for the symmetric-key of the  encryption of digital data.It is used for the cryptography.It has the key length of the 56 bits.The DES has the symmetric key block cipher.It basically takes the  64-bit plain text and 56-bit key , that produce the 64-bit Cipher text.

AES:It stands for the Advanced Encryption Standard.It is basically the secure and the fast encryption Standard that basically keeps prying eyes away from our data. AES  was basically introduced to replace the DES because we know that it uses very small cipher key and thus ,the algorithm was quite slower.It uses the S-BOX that performs the byte to byte substitution in the entire block (matrix).

Now let's see the differences between the following concepts of the DES and the AES:

Parameter DES AES

1.Key Length It's Key length is of 56 bits. It's key length varies from 128 bits,

192 bits to 256 bits.

2. Size It can encrypt 64 bits of plain text. It can encrypt 128 bits of plain text.

3. Network It's structure is based on the feistal network. it's structure is based on substitution-permutation network.

4. Rounds of Operations It perform 16 rounds of identical operations. It has the following rounds per key length:  128 bits - 10, 192 bits - 12, 256 bits - 14.

5. Security   It is basically week and in this the Triple DES(3DES) more secure as compare to the DES.

AES is more secure than the DES ,it has the de-facto world standard.

6 Derived from It  derives from Lucifer cipher. It derives from Square cipher.

S-BOX: It stands for the substitution-box.It perform the important role in the AES algorithm.That provides the confusion between the cipher text[10,11].Basically the main function of the AES is to with the use of the  a precomputed look-up-table (LUT) it has to transforms the 8 bits input data into 8 bits secret data.

In the DES , the S-BOX basically carry the  real mixing (confusion).In the DES it uses the 8 S-boxes, for each one with a 6-bit input and a 4-bit output.

Principle :

AES:  The Advanced Encryption Standard is basically works on the  Substitution and Permutation Principle.

DES: The Data Encryption Standard basically  work on Feistel Cipher structure.

THANKS, i think this will give you a better intuition about your question.If you have any doubt feel free to ask in the comment section.