Updated March 14, 2023
Difference Between DES and AES
In this topic, we will learn about the difference between DES vs AES with the introduction, key differences, and head-to-head comparison table provided below.
DES (stands for Data Encryption Standard) and AES (Advanced Encryption Standard) are symmetric block cipher. Before learning DES vs AES, do we know what the block cipher is? So let’s understand what a block cipher is. Block cipher is a cryptographic algorithm used to encrypt the plain text to produce the encrypted text (also called ciphertext) in which a cryptographic key is applied to the whole block rather than on individual bits. This algorithm always works on fixed-length blocks using the shared/ secret key. The same secret key is used to both encrypt and decrypt the text. This key is shared with both parties to encrypt and decrypt the data using it and hence protect the data from external attacks.
What is DES?
It is a symmetric block cipher that was introduced by the National Institute of Standard and Technology (NIST) in 1977. It is an implementation of Feistel Structure (a multi-round cipher that divides the whole text into two parts and works on each part individually). It works on 64- bit input key and uses 56- bit shared key to produce the ciphertext of 64-bit. In DES, whole plain text is divided into two parts of 32- a bit each before processing and the same operations are performed on individual parts. Each part undergoes an operation of 16 rounds, and after those operations, the final permutation is done to obtain the 64-bit ciphertext.
The various functions involved in the rounds are Expansion, Permutation, and Substitution, XOR operation with a round key. Decryption follows the same process as encryption but in reverse order. Although DES was considered to be less secure to encrypt the highly confidential data of government as it uses the smaller shared key, to overcome this, triple-DES was introduced, but it was also not considered as a good algorithm as it turns out to be very slow to encrypt data. Even a small change in input text produces a whole different ciphertext in DES.
What is AES?
It came into the picture after triple-DES as it was found to be slow. It is one of the most widely used symmetric block cipher algorithm used nowadays. It was introduced by the National Institute of Standard and Technology in 2001. It is at least six times faster than triple DES. Unlike DES, it works on the principle of ‘Substitution and Permutation’. It follows an iterative approach. AES works on bytes rather than bits.
In AES, plain text is considered 126 bits equivalent to 16 bytes with the secret key of 128 bits, which forms a matrix of 4×4 (having 4 rows and 4 columns). After this step, it performs 10 rounds. Each round has its subprocesses in which 9 rounds include the process of Sub bytes, Shift Rows, Mix Columns and Add Round Keys and the 10th round does include all the above operations excluding ‘Mix columns’ to produce the 126- bit ciphertext. In AES number of rounds depends on the size of the key, i.e. 10 rounds for 128- bit keys, 12 rounds for 192- bit key and 14 rounds for 256- bit keys. It is used in many protocols like TLS, SSL and various modern applications that require high encryption security. AES is also used for hardware that requires high throughput.
Head To Head Comparison Between DES and AES (Infographics)
Below are the top 9 differences between DES vs AES.
Key Differences between DES and AES
Let us discuss some of the major differences between DES vs AES.
- The main difference between DES vs AES is the process of encrypting. In DES, the plaintext is divided into two halves before further processing, whereas in AES whole block, there is no division, and the whole block is processed together to produce the ciphertext.
- AES is comparatively much faster than DES and can encrypt large files in a fraction of seconds compared to DES.
- Because of the small bit size of the shared key used in DES, it is considered to be less secure than AES. DES is considered more vulnerable to brute-force attacks, whereas AES has not encountered any serious attacks.
- Implementation of the Algorithm is evaluated on the basis of flexibility, and AES is comparatively more flexible than DES as it allows the text of various length, including 128, 192, 256 bits, whereas DES allows the encryption of text of fixed 64 bits.
- Functions used in the processing of DES rounds are Expansion, Permutation, and Substitution, XOR operation with round key, whereas the functions used in rounds of AES are Sub bytes, Shift Rows, Mix Columns and Add Round Keys.
- AES is practically efficient with both hardware and software implementations, unlike DES, which was initially efficient with only hardware.
DES vs AES Comparison table
Below is the topmost comparison between DES vs AES:
Basis of Comparison |
DES |
AES |
Developed | DES was developed in 1977 | AES was developed in 2001 |
Full-Form | DES stands for Data Encryption Standard | AES stands for Advanced Encryption Standard |
Principle | DES follows the principle of Feistel Structure | AES s based on the principle of Substitution and Permutation |
Plaintext | The plaintext is of 64 bits. | The plaintext can be 128, 192, 256 bits. |
Ciphertext | Generate Ciphertext of 64 bits | Can Generate Ciphertext of 128, 192, 256 bits |
Key Length | The key length is 56 bits. | Key length can be 128, 192, 256 bits. |
Rounds | DES contains a fixed number of rounds, i.e. 16 | AES contains a variable number of rounds depending on the size of the input, i.e. 10 rounds for 128 bit, 12 rounds for 192 bit and 14 rounds for 256 bits |
Security | DES is less secure and hardly used now | AES is much more secure than DES and is widely used nowadays. |
Speed | DES is comparatively slower than AES | AES is faster than DES |
Conclusion
Both DES vs AES is used to encrypt the data and are useful in their own way. AES came as the successor of DES to overcome its drawbacks. AES is also accepted by the U.S. government and has been accepted as a reliable algorithm to secure classified information. Although DES had made great contributions in the field of data security, it is now replaced by AES in the areas of high security.
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