Advanced Encryption Standard (AES) is the symmetric key cryptography and Rivest, Shamir, and Adleman (RSA) encryption is the asymmetric cryptography. Before learning AES vs RSA, let’s understand what is symmetric and asymmetric cryptography? Symmetric Key Cryptography uses a single key to encrypt data. In this algorithm both sender and receiver share a same secret key for encrypting and decrypting the message. While Asymmetric Cryptography uses two keys to encrypt data. One key is used for data encryption, while the other key is used for data decryption. Sender uses first key (public key) to encrypt the message and receiver uses second key (private key) to decrypt the message.

## AES vs RSA Encryption with comparison table

Parameters | AES Encryption | RSA Encryption |

Full Form | AES stands for Advanced Encryption Standard | RSA stands for Rivest, Shamir, and Adleman |

Cryptography Type | AES is symmetric key cryptography | While RSA is asymmetric key cryptography |

Number of Keys | AES uses only single key for both encryption and decryption | RSA uses two keys one for encryption and second for decryption |

Key Length | Key length varies from 128 bits, 192 bits to 256 bits | In RSA, key length is more than 1024 bits. |

Block Size | Block size can be of 128, 192, or 256 bits – depending upon the key length. | While in RSA minimum block size is 512 bits. |

Encryption Speed | AES encryption speed is faster than RSA Encryption | RSA encryption takes time for encryption and decryption |

Security | AES is more secure than RSA. | RSA is least secure as compared to AES and DES. |

Number of Round | In AES, Number of rounds depends on key length 128 bits – 10 Round 192 bits – 12 Round 256 bits – 14 Round | While RSA perform only one round |

Designed By | AES was designed by Vincent Rijmen and Joan Daemen & standardized in 2001. | RSA is created by MIT scientists (Rivest, Shamir, and Adleman) in 1977. |

## Advanced Encryption Standard (AES)

The Advanced Encryption Standard (AES) algorithm is a symmetric-key block cipher (block size 128 bit) encryption designed & by published by the National Institute of Standards and Technology (NIST) in 2001. AES is widely used today as it is a much stronger than DES and 3DES. In Advanced Encryption Standard number of rounds depends on the key length, 10 rounds for 128-bit keys, 12 rounds for 192-bit keys and 14 rounds for 256-bit keys.

Advanced Encryption Standard takes 128 bits plain text as input and produced 128 bits cipher text as output. It’s encryption process is based on a substitution-permutation network, also referred as an SP network. It consists of a series of linked operations, including replacing inputs with specific outputs (substitutions) and others involving bit shuffling (permutations).

## Rivest, Shamir and Adleman (RSA)

The RSA algorithm is an asymmetric cryptography algorithm, uses two different but mathematically linked keys –one public and one private. The Public key is used for encryption, and the Private Key is used for decryption. The public key is well known and shared publicly, but the private key is secret and it is known only to the user who owns the key and must not be shared with anyone. This algorithm was invented by Rivest, Shamir and Adleman in year 1978 that’s why name RSA algorithm.

In RSA algorithm, public key consists of two numbers where one number is multiplication of two large prime numbers. And private key is also derived from the same two prime numbers. Encryption strength totally depends upon the key size and if we increase the key size, the strength of encryption increase and the size of key is 1024 or 2048 bits. RSA is widely used in Virtual Private Networks (VPNs), email services, web browser (TLS), digital signing for code and certificates. Certificates can be used to verify the public key’s owner, by signing it with the private key of the key pair owner.

## When do we use AES and RSA encryption?

AES is commonly used for protecting data at rest. For example, we encrypt data which is in database, we will decrypt data when we need to access the data from database. In AES algorithm encryption & decryption will take place on the same platform. Another example of AES encryption is hard drive encryption – we encrypt the data when we write to the disk, and decrypt it when we read from the disk.

RSA is commonly used for protecting data at transit or we have two geographically different end-points. For example, one endpoint will encrypt the data in New Delhi, and other endpoint will decrypt it in New York. RSA uses public/private key for encryption/decryption of the data and this unique public/private key aspect of RSA algorithm helps us be secure when we are separated by many kilometers of insecurity.

## DES vs AES vs RSA

Parameters | DES Encryption | AES Encryption | RSA Encryption |

Full Form | DES stands for Data Encryption Standard | AES stands for Advanced Encryption Standard | RSA stands for Rivest, Shamir, and Adleman |

Cryptography Type | DES is symmetric key cryptography | AES is symmetric key cryptography | While RSA is asymmetric key cryptography |

Number of Keys | DES uses only single key for both encryption and decryption | AES uses only single key for both encryption and decryption | RSA uses two keys one for encryption and second for decryption |

Key Length | The size of key length is of 56 bits | Key length varies from 128 bits, 192 bits to 256 bits | In RSA, key length is more than 1024 bits. |

Block Size | The block size is 64 bits in DES | Block size can be of 128, 192, or 256 bits – depending upon the key length. | While in RSA minimum block size is 512 bits. |

Encryption Speed | The encryption process is time-consuming | AES encryption speed is faster than RSA Encryption | RSA encryption takes time for encryption and decryption |

Security | DES can be broken easily as it has known vulnerabilities. And due to smaller key, which make it less secure. | AES is more secure than RSA. | RSA is least secure as compared to AES and DES. |

Number of Round | DES involves 16 rounds of identical operations | In AES, Number of rounds depends on key length 128 bits – 10 Round 192 bits – 12 Round 256 bits – 14 Round | While RSA perform only one round |

Designed By | DES was designed by IBM. And established as a standard in 1977 | AES was designed by Vincent Rijmen and Joan Daemen & standardized in 2001. | RSA is created by MIT scientists (Rivest, Shamir, and Adleman) in 1977. |

## Conclusion

All DES, AES and RSA are used for encryption of the data and are useful in their own way. AES came as the successor of DES and RSA to overcome its drawbacks. DES is the older algorithm and AES is the advanced algorithm which is faster and more secure than both. That’s why all modern day applications rely on AES instead of the DES and RSA algorithm for secure encryption. Although DES had made great contributions in the field of data security, but now it is replaced by AES in the areas of high security.

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