## What Is AES?

**AES** is an acronym
for **Advanced Encryption Standard (AES),**also known by its original name **Rijndael**,
is a symmetric block cipher chosen by the U.S government to protect classified
information and is implemented in software and hardware throughout the world to
encrypt sensitive data. AES was established by the U.S National Institute Of
Standards and Technology (NIST) in 2001. AES comprises three block ciphers
AES-128, AES-192 and AES-256. Each cipher encrypts and decrypts data in blocks
of 128-bits using cryptographic keys of 128, 192 and 256-bits respectively.

In 2003, the AES became a default encryption algorithm for classified information as well as the first publicly accessible and open cipher approve by the NSA for top-secrete information. From 2003 to today, AES has remained as the most popular algorithm used in symmetric key cryptography.

Among cryptography experts, AES is more secure than its predecessor DES as the algorithm uses longer key lengths. It also faster in encryption when compared to DES and this makes it ideal for use in software applications, firmware and hardware that require either low latency or high throughput, such as firewalls and routers.

### Application

AES is used in many protocols such as Secure Sockets Layer (SSL), Transport Layer Security (TSL) and can be found in most modern applications and devices that need encryption functionality.

### What You Need To Know About AES

- AES was published as FIPS 197 standard in 2001. AES data encryption is more mathematically efficient and elegant cryptographic algorithm, but its main strength rests in the option for various key lengths.
- AES was designed by Vincent Rijmen and Joan Daemen.
- AES is derived from square cipher.
- AES is faster.
- AES allows the data length (plaintext size) of 128, 192 and 256-bits.
- AES divide plaintext into 16 bytes (128-bit) blocks and treats each block as a 4×4 state array and supporting three different key lengths, 128, 192 and 256 bits.
- AES algorithm structure is based on substitution-permutation principle, which involves a series of substitution and permutation steps to create an encrypted block.
- AES algorithm is more secure when compared to DES cipher algorithm and is the de-facto world standard.
- AES has a large secret key which is more secure.
- The rounds in AES are Byte Substitution, Shift Row, Mix Column and Key Addition (Addroundkeys).
- In AES, the plain text goes through 10 rounds for 128-bit algorithm, 12 rounds for 192-bit algorithm and 14 rounds for 256-bit algorithm.
- There are no known crypt-analytical attacks against AES but side channel attacks against AES implementation possible. Biclique attack have better complexity than brute-force but still ineffective.

## What Is DES?

**DES** is an acronym
for **Data Encryption Standard (DES)**and is a symmetric-key block cipher originally developed in the early 1970s by
researchers at IBM and based on an earlier design by Horst Feistel. DES was the
first encryption algorithm approved by the U.S government for public
disclosure. The simplicity of DES eventually made it to start being widely used
in a variety of embedded systems, smart cards, SIM cards and network devices
requiring encryption like modems, set-top-boxes and routers.

DES is an outdated symmetric-key method of data encryption, it works by using the same key, to encrypt and decrypt a message, and so both the sender and the private receiver must know and use the same private key.

It uses 16 round Feistel structure. The block size is 64-bit. Though the key length is 64-bit, DES has an effective key length of 56 bits, since 8 of the 64 bits of the key are not used by the encryption algorithm (function as check bit only).

### What You Need To Know About DES

- DES is a symmetric-key block cipher originally developed in the early 1970s by researchers at IBM and is based on an earlier design by Horst Feistel.
- DES algorithm was designed by researchers at IBM.
- DES cipher algorithm is derived from Lucifer cipher.
- DES is comparatively slower.
- Data encryption standard takes 64-bit plaintext as an input and creates 64-bit Ciphertext i.e it encrypts data in a block size 64-bits per block.
- In DES plaintext, message is divided into size 64-bit block each and encrypted using 56-bit key at the initial level.
- The DES algorithm structure is based in Feistal Cipher network which divides the block into two halves before going through the encryption steps.
- DES algorithm has known security vulnerabilities.
- DES has a smaller key which is less secure.
- The rounds in DES algorithm are Expansion, XOR operation with round key, Swap, S-box, P-box, Substitution and Permutation.
- In DES, the plaintext and right plaintext goes through 16 rounds of encryption process along with 16 different keys for each round.
- The known attacks against DES include Brute-force, Linear crypt-analysis and Differential crypt-analysis.

**Also Read:** *Difference Between Poly-alphabetic Cipher And Mono-alphabetic Cipher *

# Difference Between AES And DES Algorithms In Network Security In Tabular Form

BASIS OF COMPARISON | AES | DES |

Description | AES was published as FIPS 197 standard in 2001. AES data encryption is more mathematically efficient and elegant cryptographic algorithm, but its main strength rests in the option for various key lengths. | DES is a symmetric-key block cipher originally developed in the early 1970s by researchers at IBM and is based on an earlier design by Horst Feistel. |

Design | AES was designed by Vincent Rijmen and Joan Daemen. | DES algorithm was designed by researchers at IBM. |

Derivation | AES is derived from square cipher. | The DES cipher algorithm is derived from Lucifer cipher. |

Speed | It is faster. | It is comparatively slower. |

Plaintext | AES allows the data length (plaintext size) of 128, 192 and 256-bits. | Data encryption standard takes 64-bit plaintext as an input and creates 64-bit Ciphertext i.e it encrypts data in a block size 64-bits per block. |

Plaintext | It divides plaintext into 16 bytes (128-bit) blocks and treats each block as a 4×4 state array and supporting three different key lengths, 128, 192 and 256 bits. | In DES plaintext, message is divided into size 64-bit block each and encrypted using 56-bit key at the initial level. |

Basis Of The Structure | AES algorithm structure is based on substitution-permutation principle, which involves a series of substitution and permutation steps to create an encrypted block. | The DES algorithm structure is based in Feistal Cipher network which divides the block into two halves before going through the encryption steps. |

Security | AES algorithm is more secure and is the de-facto world standard. | DES algorithm has known security vulnerabilities. |

Size Of The Key | It has a large secret key which is more secure. | It has a smaller key which is less secure. |

Rounds | The rounds in AES are Byte Substitution, Shift Row, Mix Column and Key Addition (Addroundkeys). | The rounds in DES algorithm are Expansion, XOR operation with round key, Swap, S-box, P-box, Substitution and Permutation. |

Number Of Rounds | In AES, the plain text goes through 10 rounds for 128-bit algorithm, 12 rounds for 192-bit algorithm and 14 rounds for 256-bit algorithm. | In DES, the plaintext and right plaintext goes through 16 rounds of encryption process along with 16 different keys for each round. |

Attacks | There are no known crypt-analytical attacks against AES but side channel attacks against AES implementation possible. Biclique attack have better complexity than brute-force but still ineffective. | The known attacks against DES include Brute-force, Linear crypt-analysis and Differential crypt-analysis. |

**Also Read:** *Difference Between Transposition Cipher And Substitution Cipher Technique*

### Advantages Of AES Over DES

- It is most robust security protocol; it is implemented in both hardware and software.
- It is one of the most popular and widespread open source solutions all over the world.
- For 128-bit, about 2^
^{128 }attempts are needed to break. This makes it very difficult to hack it as a result it is very safe protocol. - It uses higher length key sizes such as 128, 156 and 256 bits for encryption.

### Disadvantages of AES

- AES is in counter mode is complex to implement in software taking both performance and security into consideration.
- It uses too simple algebraic structure.

### Advantages Of DES

- For encryption, DES uses the 56-bit key. Moreover, there are 256 possible keys, which means it difficult to hack.
- Change in the plaintext will drastically change the cipher text.
- Each bit of Ciphertext depends upon multiple bits of plaintext.
- DES is not a group cipher; hence DES instances can be applied many times to a plaintext.

### Disadvantages Of DES

- According to experts, there is a configuration weakness in the design of the cipher.
- S-box creates same output with two chosen input.
- The initial and final permutation is ambiguous (not exactly clear).

**Also Read:** *Difference Between Block Cipher And Stream Cipher*