Introduction to DES Algorithm
DES algorithm stands for Data Encryption Standards, also known for Data Encryption algorithm is a block cipher (works on block of text) used to encrypt a block of 64 bit plain text using 56 bit key to produce the block 64 bit cipher text. DES algorithm is based on two cryptographic attributes i.e. substitution and transpositions, consist of 16 rounds where each round performs transpositions and substitution. Two variations are available double DES and triple DES.
DES Algorithm
Data Encryption System is typically an outdated encryption technique. DES follows a symmetric-key method of data integration.
It was originated more than five decades earlier, back in the early 1970s. It was originally designed by the developers of IBM. Soon it was developed, DES was adopted by the government of the United States. The US government adopted it as an official Federal Information Processing Standard in the year 1977. Although data to be encrypted using DES algorithm were basically unclassified government computer data.
Later on, seeing the necessity and usage of the algorithm, the US government decided to disclose it for public usage. This move by the government of the United States ensured that all other industries where the need for good data encryption algorithm was 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 DES algorithm is:
It was designed by IBM and was first published in 1975. DES was derived from Lucifer.
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Triple DES, G-DES are few of its successor.
Few other details about ciphertext are that it consists of 64-bits out of which usable is 56-bits only.
And it follows 16 rounds for encrypting data.
Now, in the next section, we will like to discuss in deep about how this algorithm was applied to the sensitive data.
Creation of DES Logic/A dig deeper into Algorithm Process –
We will divide this section into two sub-categories:-
- Encryption Logic
- Decryption Logic
Let us discuss this one by one.
Encryption Algorithm
- Data Encryption Standard is a block cipher, which means that any cryptographic key and its related algorithm is applied on a block of data. This block of data is generally of 64-bit blocks. DES does not follow a bit-by-bit concept. Hence, it will not pick one bit and then process it. It computes or processes a complete block of 64 bit of data.
- Now, this each block of 64-bit data is enciphered using the secret key which in turn 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
Decryption Algorithm
- 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. Let’s have a look on that section too
Drawbacks of DES Algorithm
For any cipher, who wants to decrypt the encrypted method has to use a brute force attack. 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 hit and trial method, where intruder tries to hit again and again till he decrypts the message.
Generally, the length of this combination determines the number of possible combinations. 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 for hit and trial method or for brute force is quite low which opens lots of vulnerabilities.
Hence this is the main reason why DES algorithm was not practiced.
Explanation with Illustration
A typical example to illustrate DES algorithm is the conversion of a plain text say “It’s fun to learn” to the encrypted text. Let us assume that DES key which is to be used for this 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”
Isn’t that great !!!
Why DES Algorithm is Important?
Before moving ahead with our discussion on this topic, we would like to discuss why the DES algorithm is that much important.
You can debate easily that 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 above question is its base concept. Yes, the concept on which it was laid the i.e. concept of encrypting the message before transmitting formed the very foundation for 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 to encryption technique and provided a very first mechanism on how this encryption could be applied and achieved. It is DES algorithm which laid the foundation for other algorithms which used the very basics concept and further improved it to make better encryption technique.
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