DES Algorithm

Introduction to DES Algorithm

DES algorithm stands for Data Encryption Standards, also known as Data Encryption algorithm, a block cipher (works on a block of text) used to encrypt a block of 64-bit plain text using a 56-bit key to produce the block 64-bit ciphertext. DES algorithm is based on two cryptographic attributes, i.e. substitution and transpositions, consisting of 16 rounds where each round performs transpositions and substitution. Two variations are available to double DES and triple DES.

DES Algorithm

Data Encryption System is typically an outdated encryption technique. Instead, DES follows a symmetric-key method of data integration.

It was originated more than five decades earlier, back in the early 1970s. The developers of IBM originally designed it. Soon it was developed, the government of the United States adopted DES. The US government adopted it as an official Federal Information Processing Standard in the year 1977. Although data to be encrypted using the DES algorithm were basically unclassified government computer data.

Later on, seeing the algorithm’s necessity and usage, the US government decided to disclose it for public usage. The United States government moved this move ensured that all other industries needed for good data encryption algorithms were quickly adopted. Major industries which picked up this encryption algorithm were like the banking industry, finance industry, communication industry and many more.

Some other important and fascinating data about the DES algorithm is:

• It was designed by IBM and was first published in 1975. DES was derived from Lucifer.
• Triple DES, G-DES are a few of their successors.
• Few other details about ciphertext consist of 64-bits, out of which usable is 56-bits only.
• And it follows 16 rounds for encrypting data.

Creation of DES Logic/A dig deeper into Algorithm Process

We will divide this section into two sub-categories:

• Encryption Logic
• Decryption Logic

1. Encryption Algorithm

• Data Encryption Standard is a block cipher, which means that any cryptographic key and its related algorithm are applied to a data block. This block of data is generally of 64-bit blocks. However, DES does not follow a bit-by-bit concept. Hence, it will not pick one bit and then process it. Instead, it computes or processes a complete block of 64 bits of data.
• Each block of 64-bit data is enciphered using the secret key, which turns into a 64-bit ciphertext.
• This 64-bit ciphertext is generated by using different means of permutation and substitution methods.
• This process involves 16 rounds which could run under four different modes.
• This block hence encrypted, is individually encrypted.

2. Decryption Algorithm

• The decryption algorithm is just the reverse of the encryption process.
• To decrypt the encrypted message, all steps are processed in reverse order.

As of now, we are now aware of encryption and decryption logic. However, the DES algorithm has some major drawbacks, which led to the failure of this algorithm. So let’s have a look at that section too.

Drawbacks of DES Algorithm

Any cipher who wants to decrypt the encrypted method has to use a brute force attack. A brute force attack is a way or mechanism in which several combinations are randomly applied to decrypt the message. In brute force, different combinations are applied one by one until it hits the right combination. Thus brute force works on the hit and trial method, where the intruder tries to hit again and again till he decrypts the message.

Generally, the length of this combination determines the number of possible combinations. For example, a DES uses 64 bits of encryption logic. Out of this available 64 bits, 8 bits are used for parity check. Hence effective bits now boils down to 56-bits only. These 56-bits apparently forms a maximum combination of 2^56. Hence only 2^56 attempts are required to decrypt a message using brute force logic. This particular combination of hit and trial methods or brute force is quite low, which opens many vulnerabilities.

Explanation with Illustration

A typical example to illustrate the DES algorithm is converting plain text, say, “It’s fun to learn”, to the encrypted text. Let us assume that the DES key which is to be used for encrypting this plain text is “cipher”. Now, on applying our encryption logic the ciphertext generated will be “90 61 0c 4b 7f 0e 91 dd f4 23 e4 aa 9c 9b 4b 0a a7 20 59 2a bb 2d 59 c0”. Similarly, we can use the decryption technique using the same key viz. “cipher” on the encrypted message to get our original text which is “It’s fun to learn.”

Why is the DES Algorithm Important?

• You can debate easily that the DES algorithm is already outdated; it is not in practice now. Even messages encrypted using this algorithm could be decrypted easily. So why is this so important?
• Well, a simple and straightforward answer to all the above questions is its base concept. Yes, the concept on which it was laid, i.e. concept of encrypting the message before transmitting, formed the very foundation for the whole security concept for the digitally transmitted message.
• This is the main cause of why the DES algorithm has such special and high importance.

Conclusion

DES algorithm has proved a milestone to the importance of network security, or we can say importance to the security of message which needs to be transmitted over any medium. DES algorithm laid the foundation for the encryption technique and provided the first mechanism for applying and achieving this encryption. In addition, the DES algorithm laid the foundation for other algorithms that used the very basics concept and further improved it to make better encryption techniques.

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