Do you think IIT Guwahati certified course can help you in your career?
Introduction
Data Encryption Standard, abbreviated as DES, is a block cipher and a symmetric cipher, i.e., the same key is used for encryption and decryption.
The entire Data Encryption Standard procedure marks the input as a 64-bit plain text block and output as a 64-bit ciphertext. The key length of DES is 56 Bits.
The four steps for the Data Encryption standard are as follows:
Initial Permutation
16 Feistel Rounds
Swapping
Final Permutation(also known as inverse initial permutation)
Key Features of Data Encryption Standard (DES)
Symmetric Key Cryptography in DES
Data Encryption Standard (DES) uses symmetric key cryptography, which means the same secret key is used for both encryption and decryption. In other words, the sender and receiver must share the same key in advance to communicate securely. When a sender encrypts the data using this key, the receiver uses the same key to decrypt and read the original information.
This method is faster and more efficient than asymmetric key cryptography because it requires less processing power. However, it also raises security concerns. If someone gains access to the shared key, they can easily decrypt the data. So, key management and secure key exchange are critical.
DES works well for closed systems where key exchange can be controlled securely. While newer encryption methods have replaced DES in many areas, the concept of symmetric key cryptography remains widely used due to its speed and simplicity.
Difference between Block Cipher vs Stream Cipher
DES is a block cipher, which means it processes data in fixed-size blocks, typically 64 bits at a time. It takes each block of plaintext, encrypts it using the same key, and produces a block of ciphertext. This approach helps in maintaining structure and is easy to implement.
On the other hand, a stream cipher processes data one bit or byte at a time, encrypting each piece as it flows. This makes stream ciphers more suitable for real-time applications, such as voice and video transmission, where low latency is important.
Block ciphers like DES are generally more secure for file encryption because they work well with structured data and allow for various modes of operation (like ECB, CBC). Stream ciphers are faster for continuous data streams but may be more vulnerable if the key is reused.
DES uses a block cipher because it offers a good balance between security, efficiency, and flexibility, especially for files and stored data that can be processed in chunks.
Working of Data Encryption Standard
The same cycle works when there is a need to produce a 56-bit key.
Removal of every eighth bit
The specifications required for data encryption standard are as follows:
Additional Processes: Initial and Final Permutation
Round Function
Scheduled Key
Initial and Final Permutation
Initial and Final Permutation works like the inverse of each other with the depiction of Permutation Boxes(also known as P- Boxes). They do not have any cryptographic significance in Data Encryption Standard.
Round Function
The entire performance of Data Encryption Standard as Cipher Feistel is based on the Round Function. The function signifies producing a 32-bit output with the application of a 48-bit key to the rightmost 32 bits.
1. Expansion Permutation Box: As the right input only consists of 32-bit and the round key consists of 48 bits, there is a need to expand the right input from 32 bits to 48 bits.The graphical representation of permutation logic in the Data Encryption Standard specification is below:
2. XOR: Data Encryption Standard performs XOR operation between the expanded right input and the round key. This is the only step that involves the usage of the round key.
3. S-Boxes: The S-Boxes deal with the real mess. Data Encryption Standard uses 8 S-Boxes, consisting of 6-Bit input and a 4-Bit output.
4. Straight Permutation: The 32-bit output obtained from the 8 S-boxes traverses through the straight permutation based on the following depiction:
Analysis of Data Encryption Standard
The Data Encryption Standard customizes the satisfaction of both the properties of the block cipher. The properties are described as
Complete Structure: Ciphertext consists of transforming many bits of plain text.
Avalanche Effect: Single change in plain text results in a drastic change in Cipher Text.
During the last few years, cryptanalysis has discovered some flaws in DES when the keys used are weak ones. These keys are should be avoided.
DES has proven to be an exceptionally well-designed block cypher. Except for an exhaustive key search, there have been no notable cryptanalytic attacks on DES.
Practical Applications of DES
How DES Was Used in Early Security Systems
In the 1970s and 1980s, the Data Encryption Standard (DES) played a key role in protecting digital information. Developed by IBM and adopted by the U.S. National Institute of Standards and Technology (NIST) in 1977, DES became the first federally approved encryption standard for securing sensitive but unclassified data.
At the time, DES was widely trusted and used in various industries. It was commonly implemented in secure communication systems, early computer networks, and digital data protection tools. DES allowed organizations to protect confidential data from unauthorized access, especially in systems where online data exchange was just emerging.
One of its most notable early uses was in securing banking transactions and financial records, where it helped prevent data breaches. Government agencies also adopted DES for non-classified data encryption, ensuring confidentiality in growing digital systems.
Despite its eventual replacement, DES marked a major step forward in standardized digital security.
DES in Banking, Military, and Government
During its peak, DES was a standard encryption tool in critical sectors like banking, military, and government. In the financial industry, DES was used to secure ATM transactions, credit card payments, and electronic fund transfers. Banks relied on DES to encrypt PINs, account details, and transaction data, ensuring safe and private operations for customers worldwide.
In the military, DES protected internal communications and mission-sensitive information. While not used for top-secret data, it served as a reliable solution for encrypting routine communications and databases within the armed forces.
Government agencies adopted DES to secure non-classified yet sensitive information, offering a balance between performance and security. One major supporter was the Financial Services Technology Consortium (FSTC), which promoted DES in financial systems to protect data across networks used by multiple institutions.
As computational power increased, DES’s vulnerabilities became more apparent. This led to its gradual phase-out and replacement by stronger encryption methods like Triple DES (3DES) and AES. However, DES laid the groundwork for modern encryption standards and remained a trusted solution for many years.
The Future of Data Encryption
Why DES Is No Longer Considered Secure
The Data Encryption Standard (DES) is no longer secure in today's digital world because of its short key length of 56 bits. While 56 bits were enough in the 1970s, modern computers can now try all possible key combinations in a short time using brute-force attacks.
In 1998, the Electronic Frontier Foundation (EFF) built a special machine that cracked DES in just a few days. This event clearly showed that DES could no longer protect sensitive data from attackers with advanced tools and resources.
As hardware became faster and cheaper, DES’s weakness became more obvious. Hackers could break the encryption without needing a lot of time or money. Because of this, security experts and organizations stopped using DES for protecting confidential information.
Due to these serious security flaws, DES was officially retired and replaced by stronger encryption methods like Triple DES (3DES) and later, AES (Advanced Encryption Standard).
The Shift to Advanced Encryption Standard (AES)
To solve the weaknesses of DES, the Advanced Encryption Standard (AES) was introduced in 2001. AES offers longer key lengths—128, 192, and 256 bits—making it much harder for attackers to break through brute-force methods.
AES was chosen after a public competition held by the National Institute of Standards and Technology (NIST). It stood out for its high performance, strong security, and efficiency across different platforms. Unlike DES, AES can secure large amounts of data quickly without slowing down systems.
AES quickly became the new standard for encryption used by governments, businesses, and software developers worldwide. It protects data in VPNs, secure web connections (SSL/TLS), mobile apps, and encrypted file systems.
In comparison to DES, AES offers stronger protection, supports larger key sizes, and is more resistant to modern attacks. Because of these features, AES has replaced DES in nearly all encryption systems today and remains the most trusted encryption algorithm used globally.
Frequently Asked Questions
How many iterations are there in DES Algorithm?
There are 16 iterations in Data Encryption Standard Algorithm.
What is the key length of the Data Encryption Standard Algorithm?
The key length of the Data Encryption Algorithm is 64 Bits.
What is the size of the initial permutation matrix?
The size of the initial permutation matrix is 8*8.
What is the size of the round key in the DES algorithm?
The size of the round key in the DES algorithm is 48 bits.
What is the size of round input in the DES algorithm?
The size of round input in the DES algorithm is 32 bits.
Conclusion
Congratulations on finishing the blog!! After reading this blog, you will grasp the concept of the Data Encryption Standard.
34+ registered 
