Data Encryption Standard Algorithm in Cryptography | iCert Global

Nowadays, we spend much time on the internet. Whether we save our personal data, watch videos, shop, or work, we rely increasingly on the internet.

Since we make use of the internet a lot, it's extremely vital to protect our information. Data encryption is one of the methods of securing information on the internet, and it's also one of the oldest and most widespread methods. When discussing encryption, we cannot exclude DES.

What is Data Encryption Standard (DES)?

DES is short for Data Encryption Standard. There are computers that exist specifically to attempt to decrypt the DES encryption, but it's still very popular.

What is the DES Algorithm in Cyber Security?

The DES (Data Encryption Standard) algorithm is an encryption technique used to secure information. It was developed in the early 1970s by IBM and then later became a US government standard.

Initial Permutation (IP)

When we start encrypting information using DES, we first divide the plain text into smaller chunks of 64 bits. Next, the Initial Permutation (IP) is performed. This is similar to scrambling the positions of the bits in the chunk.

Step 1: Key Transformation

The DES uses the key of 56 bits. But this key is derived from a key of 64 bits by stripping off some of its bits. This process converts the 56-bit key into a 48-bit key.

Step 2: Expansion Permutation

Secondly, we extend the Right Plain Text (RPT) of 32 bits to 48 bits. We divide the 32-bit block into 8 small 4-bit blocks. Two additional bits are appended to each block, and the bits are re-arranged. This will form a 48-bit block.

Triple DES Algorithm

Triple DES is a more secure version of DES. Triple DES employs three keys: k1, k2, and k3.

Key Takeaways

• DES was superseded because its 56-bit key grew too small as computers became more powerful. Encryption strength relies on the key size, and with more sophisticated technology, DES was unable to match the requirement for stronger security.

How Does DES Work? – The Basic Steps

1. Begin with the 64-bit plain text.

2. Use the Initial Permutation (IP) to randomize the bits.

3. Divide the permuted text into Left Plain Text (LPT) and Right Plain Text (RPT).

DES Encryption Process – More Details

1. Key Transformation: Convert the 56-bit key into a 48-bit key.

2. Expansion Permutation: Convert the 32-bit RPT into 48 bits.

3. S-Box Permutation: Utilize special tables (referred to as S-boxes) to swap and substitute bits.

DES Modes of Operation

The DES algorithm can be implemented in various modes based on how you prefer the encryption to be performed. Below are the five primary modes of operation for DES:

1.Electronic Codebook (ECB): Each 64-bit data block is encrypted and decrypted individually.

2. Cipher Block Chaining (CBC):Each 64-bit plaintext block is XORed with the preceding block's ciphertext prior to encryption.

3. Cipher Feedback (CFB): The last ciphertext is applied as the input to the encryption algorithm, producing a new result that is thereafter XORed against the plaintext.

4. Output Feedback (OFB): Likewise with CFB, except that rather than applying the encryption algorithm to the ciphertext, the algorithm applies it to the result of the preceding DES encryption pass.

5. Counter (CTR): A ciphertext block is XORed against every plaintext block, and the counter is incremented to produce each and every next block.

Applications of DES Algorithm

Even though DES is not commonly used in contemporary security networks because of its comparatively weak 56-bit key, there are a few areas where DES remains utilized, particularly in old systems. Some of these areas include:

1. Random Number Generation: DES may be utilized to create random numbers for different purposes, although it tends to be replaced by newer secure algorithms now.

2. When Not-so-Strong Encryption is Needed: For some situations where high security isn’t required, DES can still be used because it’s fast and easy to implement.

3. Triple DES (3DES): This is a stronger version of DES that applies the DES algorithm three times, using three different keys, which makes the encryption much more secure (168-bit key length). Triple DES is still used extensively even now, though it's being replaced by newer encryption algorithms such as AES.

Advantages and Disadvantages of DES Algorithm

Advantages of the DES Algorithm:

1. Government Standard: DES was made a standard by the U.S. government, meaning it was well accepted and trusted for decades.
2. Faster on Hardware: When applied on hardware (such as dedicated encryption devices), DES is quicker than software implementations. This is the reason it was frequently utilized in systems where speed was a high priority.

3. Triple DES (3DES) for Increased Security: Triple DES uses the DES algorithm three times with three different keys (168-bit key total), making it more difficult to break. This significantly enhances security over the original DES.

Disadvantages of the DES Algorithm:

1. Poor Security: DES has a 56-bit key, which is too small according to today's cryptographic standards. Therefore, it is susceptible to all kinds of attacks.
2. Susceptible to Brute Force Attacks: Due to the tiny key size, DES is vulnerable to brute force attacks, where the attacker attempts all possible keys until the correct key is discovered. With today's computing power, a brute force attack on DES can be conducted quite easily.
3. DES Cracker Machines Availability: Special purpose machines such as the Deep Crack machine have been constructed to decrypt DES using the method of trying all possible keys. This proves the vulnerability of DES against new technology and advancing computational capabilities.

Steps for DES Encryption:

1. Permutate the 64-bit Plaintext : The 64-bit plaintext is initially permutated through the Initial Permutation (IP). This means rearranging the bits in a particular sequence as given by the IP table.

The resulting 64-bit block is split into two halves:

• Left Plain Text (LPT) - 32 bits
• Right Plain Text (RPT) - 32 bits

2. Several Rounds of Operations: The LPT and RPT go through 16 rounds of transformations.

3. XOR Operation: It is expanded from 32 bits to 48 bits by applying an Expansion Permutation. The expanded RPT is then XORed with a 48-bit key derived from the key schedule (a different 48-bit round key is used in each round).

4. S-Box Substitution: The result is then passed through S-boxes (Substitution boxes) after the XOR.

5. XOR with Left Plain Text (LPT): The output of the S-box is then XORed with the LPT.

6. Swap LPT and RPT: The last RPT is saved in LPT for use in the subsequent round.

7. 6 Rounds Repeat: There are 16 rounds, with each round operated on by a different key (derived from the initial 56-bit key).

8. Swap and Last Permutation: Now, the last round is concluded, and then the LPT and RPT are swapped.

Steps for DES Decryption

• Decryption in the DES (Data Encryption Standard) algorithm is virtually the same as encryption, with an important distinction: the key order is reversed. That is, the same operations are used, but in reversed key order to retrieve the original plaintext from the ciphertext. These are the nitty-gritty steps:
• Reverse Order of Round Keys: During the encryption process, 16 various 48-bit keys are employed for the 16 rounds. To decrypt, you reverse the sequence of these keys.
• Key 16 becomes Key 1,
• Key 15 becomes Key 2,and so forth.
• the Encryption Process: Once the keys are reversed, use the same encryption process on the ciphertext, but with the new reversed keys.
  • This includes:
• First Permutation (IP): Begin by permuting the ciphertext in a manner similar to the plaintext for encryption.
• 16 Rounds: On each round, apply the same reversed key that was applied as the counterpart and perform XORing, substitution from S-boxes, and interchange.
• Final Permutation (IP⁻¹): Following all of these rounds, run the last inverse permutation so the original 64-bit plaintext can be formed again.

Effectively, decryption is simply encryption in reverse keys being applied.

Why Study DES Even If It's Becoming Obsolete?

Even though DES is no longer popular because of its susceptibility to brute-force attacks (thanks to its 56-bit key length), it has tremendous historical and pedagogical significance. Here are some reasons why studying DES remains important:

1. Core Knowledge: DES was the first popular encryption standard and the foundation for contemporary cryptographic schemes.
2. Historical Perspective: DES was a key component of cryptography in the 1980s and 1990s. Knowing its limitations and development is important in grasping today's cryptography landscape.
3. Cryptography Basics: Knowing DES helps you appreciate the mechanism of permutation, substitution, and key expansion, which are all important concepts for today's encryption

Want to Enhance Your Cybersecurity Expertise?

If you're interested in cybersecurity, studying encryption is only the beginning. The area is broad, and there are many different roles and specializations you can specialize in. Some of these include:

•Certified Ethical Hacking (CEH): Train to think like a hacker and learn how to defend systems from attack.

•Certified Information Systems Auditor (CISA): Learn to audit and evaluate IT systems for vulnerabilities.

• CompTIA Security+ Certification: Develop a strong foundation in cybersecurity concepts, risk management, and network security.

Key Advantages of CISSP Certification:

• In-Depth Learning: You'll receive more than 60 hours of intensive learning that addresses a broad spectrum of topics, ranging from establishing secure IT architectures to creating and sustaining secure business environments.

• Best Practices: The course instructs you in globally accepted security standards and practices, which are necessary for managing the growing complexity of cybersecurity.

• Hands-On Practice: You get five simulation test papers for practice on CISSP exam to ensure you're ready for the exam.

• CPE Credits and Exam Voucher: The course offers 30 CPEs (Continuing Professional Education) as needed and a CISSP exam voucher to enable you to pass the certification exam.

How to obtain Cyber Security certification? 

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Conclusion

The Data Encryption Standard (DES) was instrumental in the development of cryptography and the establishment of encryption algorithms used today. Although DES is no longer the most secure option because it has a vulnerability in its 56-bit key, it is still a foundational subject for any individual seeking to learn about the principles of encryption. Studying DES provides a strong foundation upon which to base the study of more complex encryption methods such as AES (Advanced Encryption Standard) and Triple DES.

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