What is DES algorithm?

Safalta Expert Published by: Aryan Rana Updated Mon, 19 Sep 2022 10:42 PM IST


DES is a block cypher algorithm. It changes blocks of 64-bit plaintext into blocks of 48-bit ciphertext using symmetric keys. The IBM team created the DES Algorithm in the 1970s. The National Institute of Standards and Technology has since approved it (NSIT).

Table of Content

1. Describe the DES algorithm
2. DES Triple Algorithm
3. DES Algorithm Procedure
4. Modes of Operation for DES
5. Implementation of the DES Algorithm
6. Uses for the DES algorithm
7. Advantages of the DES Algorithm
8. Disadvantages of the DES algorithm
9. Conclusion

Understanding data encryption is a crucial cyber security ability. The DES algorithm has been used for data encryption for many years. Learning how it operates and how it may be put into practice makes sense. We'll talk about the DES algorithm's operation and application in this blog. The triple DES algorithm will also be covered.  If you are interested in Digital Marketing or Graphic Designing and want to learn these interesting courses then click on the links mentioned Digital Marketing Course and Graphic Designing course

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Describe the DES algorithm

DES is a block cypher algorithm. It changes blocks of 64-bit plaintext into blocks of 48-bit ciphertext using symmetric keys.

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The IBM team created the DES Algorithm in the 1970s. The National Institute of Standards and Technology has since approved it (NSIT).

Symmetric keys are those employed by the DES encryption algorithm, which encrypts and decrypts data using the same key.

DES Triple Algorithm

Block encryption called Triple DES uses the DES algorithm three times. Typically, it employs the three keys k1, k2, and k3. Three keys are utilised: the first key, k1, the second key, k2, and the third key, k3, which is used to re-encrypt.

There is a version of the triple DES that only needs two keys, where k1 and k3 are the same.

DES Algorithm Procedure

Let's examine the steps that make up the DES algorithm:
  • The 64-bit plaintext block is given to the initial permutation (IP) function.
  • The plaintext is used when doing the IP.
  • The permutated block is then divided in half by the IP. The right text and left plain text (LPT) are the names of the two parts (RPT).
  • All LPTs and RPTs are 16 times encrypted.
  • After joining the LPT and RPT, this block is subjected to the final permutation (FP).
  • It's time to create the 64-bit ciphertext.

There are five stages in the encryption procedure (step 4):
  • Important transition
  • Swap, S-Box permutation, P-Box permutation, XOR, and expansion permutation
  • The same procedure is used for decryption, but with the 16 keys' order inverted.

Modes of Operation for DES

The various DES modes of operation include the ones listed below:

Electronic Codebook (ECB): In this mode, each 64-bit block is encrypted and decrypted separately.
Cipher Block Chaining (CBC): In this mode, each 64-bit block is reliant on the one that came before it. 
Cipher Feedback (CFB): In this mode, the encryption algorithm is fed the preceding ciphertext as its input. The output is pseudorandom as a result. The plaintext and this output are then XORed. The following ciphertext unit is so produced.
Output Feedback (OFB): This mode is similar to CFB with the exception that the output of the preceding DES serves as the input for the encryption process.
CTR counter: Every block of plaintext in this mode is XORed with an encrypted counter. For each subsequent block, the counter is increased.

Implementation of the DES Algorithm

For the DES algorithm to be used, a security provider is required. The initial step in the implementation process must involve choosing one of the various providers that are offered on the market. Your choice of supplier will be influenced by the language you employ. This might be Java, C, Python, or MATLAB.

After deciding on the supplier, you must choose how the key will be generated. You have the option of having the key created at random by the key generator or making your own key. For this, you can use either plaintext or a byte array.

It is essential to test the encryption so you can be sure it is being used correctly.

Uses for the DES algorithm

When weak encryption is required, the DES algorithm is utilised. It can be applied to permutation generators or random number generators. The development of triple DES legacy systems with three keys is one of the DES algorithm's most significant practical applications.

Advantages of the DES Algorithm

The benefits include the following:
  • Since 1977, the algorithm has been in use. Technically speaking, the algorithm has no flaws. The most effective methods of attack against the DES algorithm remain brute force ones.
  • The US government established DES as the benchmark. Every five years, the government must recertify DES, and if necessary, it must request its replacement.
  • DES has also been recognised as a standard by the American National Standards Institute (ANSI) and the International Organization for Standardization (ISO). This indicates that the algorithm is available for everyone to use and learn.
  • Although DES was created for hardware, it is only somewhat quick in software.

Disadvantages of the DES algorithm

The drawbacks include the following:
  • The 56-bit key size of the DES algorithm is arguably its worst drawback. A million DES operations may be encrypted and decrypted by chips in a second. For $1 million, you may get a DES cracking machine that will search all the keys in around seven hours.
  • Hardware can readily implement DES. However, it runs extremely slowly on it because it was not intended for software.
  • As technology advances, it has become simpler to decrypt the DES-encrypted code. AES is recommended today over DES.
  • As a symmetric encryption method, DES uses a single key for both encryption and decryption. We won't be able to get any decipherable data if that one key is gone.


64 bits of plaintext can be encrypted into 64 bits of ciphertext using the symmetric block cypher DES. Both the encryption and decryption processes use the same algorithm. The decryption process is the exact reverse of the encryption process, which is the only distinction.


Is the DES algorithm outdated?

The DES, which was adopted in 1977 for use by federal agencies to safeguard sensitive, unclassified information, is being retired because it no longer offers the security required to safeguard information held by the federal government.

Where is the DES algorithm used?

All U.S. government financial operations involving electronic cash transfers, including those carried out by Federal Reserve System member institutions, are now required to use the DES algorithm.

Why is DES viewed as being weak?

First off, the fact that DES keys are just 56 bits long and have 256 potential combinations makes them weak.

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