Data Encryption Standard: How It Works? [DES vs AES vs 3DES]

Data encryption standard is a secret code making technique. This actually refers to an encryption algorithm that is being widely used in the world.

It was submitted in the 1970s by IBM in order to secure the sensitive data.

Then with time, this algorithm proved to be vulnerable to attacks and was then replaced by the advanced encryption standard(AES).

Read this impressive article to know how does data encryption standard work, the algorithm steps, AES vs DES, triple data encryption standard, and a lot more.

Data Encryption Standard Definition

DES is a symmetric key algorithm used to encrypt the digital data.

This block cipher encrypts the data, and the size of each block is 64 bits. In simple words, it takes 64 bits plain text as input and gives a 64 bits ciphertext output.

Its popularity declined because it was found to be vulnerable against some powerful attacks. Due to this, it has been replaced by some modern encryption algorithms.

How Does the Data Encryption Standard Work?

The DES takes a secret message as an input.

Next, it takes the 64-bit key that is used for both encryption and decryption. Then it gives a ciphertext as an output.

In this algorithm, the secret key is known to both the sender and the receiver. This way, they can communicate securely.

Step 1:

Firstly the 64-bit plain text goes through an initial permutation. Here the bits are rearranged into permuted blocks called the LPT 32 bit (left plain text) and the RPT 32 bit (right plain text).

Step 2:

Next, this LPT and the RPLt undergo 16 rounds of DES encryption with a 56-bit key.

Step 3:

Here the 64-bit ciphertext is obtained. This is done by integrating the 32 bit LPT and the 32-bit RPT after their 16th round. Now they form a 64-bit block in which the final permutation is implemented.

DES Decryption

The same DES algorithm that is used to encrypt the text is used for the text decryption too.

For the decryption, the only change is that the algorithm is reversed. The initial permutation, final permutation, and the subkeys sequence are reversed.

Advantages of DES Algorithm

It has a 56-bit key, which makes 2^56 possibilities. This means it would be a bit difficult for the hackers to get the correct key from these many possibilities.

The encryption and decryption processes are done using the same algorithm, with the exception that the algorithm needs to be reversed. This is quite convenient in terms of the hardware and software requirements.

Why is DES Insecure?

It was a superb algorithm of its time. But at the starting of the 21st century, the DES appeared to be insecure. The main reason was the length of its short secret key.

Furthermore, DES can be a victim of attack using the linear cryptanalysis.

AES vs. DES

DES is an old algorithm. Moreover, it has a short key size that can be brute-forced now.

Furthermore, it makes use of the 64-bit block, which can have issues with encrypting big data.

On the Other hand, AES works with 128, 192, and 256 bits key.

Furthermore, this algorithm makes use of a 128-bit block that is quite convenient for both the hardware and the software.

DES was developed in 1977 while the AES came in 2000.

In terms of security, DES is proven to be inadequate now, while the AES is considered to be pretty secure.

The number of rounds in AES is dependent on the length of the key. On the other hand, the DES has 16 rounds of operations.

The Triple Data Encryption Standard

This algorithm is based on DES and is quite reliable.

You can easily modify your existing software to use the triple DES. Triple DES has a longer key length and is a powerful version of the data encryption standard.

How 3DES Work?

3DES makes use of three 64 bit keys. You can also enter the complete 192 bit key rather than typing each of them individually. Then the user-provided key is broken down into three subkeys.

The keys are padded if required. Then each of them becomes 64 bits ling.

The encryption procedure in 3DES is the same as that of the regular DES with the exception that the algorithm is repeated thrice, and due to this, its name is 3DES. For decryption, the encryption process is executed in reverse.

Triple Des Algorithm Steps

In 3DES, the encryption-decryption process involves the following steps.

1. Firstly the encryption of the plaintext block occurs using the single DES with the key K1.
2. Next, the decryption of the step 1 output occurs using the single DES with the key K2.
3. Then the step2 output is encrypted using the single DES with the key K3.

This step 3 output is the ciphertext.

How to Decrypt Triple DES Algorithm?

For decryption, this process is reversed, i.e., first decryption occurs using the key K3, then the encryption with the key K2, and in the end, the decryption with the key K1.

Why is the Middle Portion of Triple-DES Decryption Rather Than Encryption?

Well, the benefit of doing so is that the 3DES users can easily decrypt the data that was encrypted by the single DES. They can decrypt it by repeating the key.

Final Words

Using the Feistel structure, a number of ciphers have been created.

DES is a popular one among these. It is a 16 round Feistel cipher that takes a 64-bit secret key and an input of 64 bit. This algorithm works in 3 steps.

Firstly, the initial permutation is performed, then the rounding function, which is repeated 16 times, and in the end, the final permutation takes place.

The DES was found to be vulnerable against some attacks, and due to this, its popularity decreased. You can use the triple DES or the AES.

Well, AES is considered to be more efficient and is exponentially stronger than the data encryption standard and the 3DES.