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With the rapid development of internet technology and the increasing popularity of e-commerce, data encryption technology plays a very important role in data security. Information security has two aspects: security protocol and cryptographic algorithm and the latter is the foundation and core technology of information security. Advanced Encryption Standard (AES) encryption algorithm is one of the most commonly used algorithms in symmetric encryption algorithms. Such algorithms face issues when used in the context of key management and security functions. This paper focuses on the systematic analysis of these issues and summarizes AES algorithm implementation, comprehensive application and algorithm comparison with other existing methods. To analyze the performance of the proposed algorithm and to make full use of the advantages of AES encryption algorithm, one needs to reduce round key and improve the key schedule, as well as organically integrate with RSA algorithm. Java language is used to implement the algorithm due to its large library, then to show the efficiency of the proposed method we compare different parameters, such as encryption/decryption speed, entropies and memory consumption...) with a classic algorithm. Based on the results of the comparison between AES and the hybrid AES algorithm, the proposed algorithm shows good performance and high security. It therefore can be used for key management and security functions, particularly for sharing sensitive files through insecure channel. This analysis provides a reference useful for selecting different encryption algorithms according to different business needs.

In cryptography, there are many types of encryption algorithms. Generally speaking, they can be divided into three types: symmetric encryption algorithm, asymmetric encryption algorithm and single-entry encryption algorithm. Different encryption algorithms are used in security, encryption efficiency, implementation complexity, there are big differences in the best places to use. Among them, the symmetric encryption algorithm uses the same key for encryption and decryption. The algorithm is reversible or decipherable. Common algorithms include IDEA, DESX, RC4, RC5, RC6, DES, 3DES and AES. Symmetric encryption algorithms are often used in situations where large amounts of data are encrypted or data is frequently sent. Asymmetric encryption algorithm means that different public and private keys are used for encryption and decryption. Sometimes, asymmetric encryption is also called public key encryption. The algorithm is also reversible. Common algorithms include RSA, DSA, ECC, Diffie-Hellman, and El. Gamal et al. Asymmetric encryption algorithms are commonly used for public key encryption, private key decryption, private key signature, public key verification, small amount of sensitive information encryption, digital signature, and so on. The single-entry encryption algorithm and the hash encryption algorithm are unidirectional irreversible algorithms. The encrypted data cannot be decrypted. Common algorithms include MD5 and SHA. The algorithm is commonly used in non-restorable password storage, information integrity checks, etc., such as file verification, digital signature, authentication protocol, and the like How to encrypt critical information has become the focus of attention in the area of IT and networking [

In this paper we proposed to solve the problem of difficult key management of AES algorithm and low efficiency of RSA by reducing the execution round and the modification of the initial key. The complex encryption algorithm is introduced and Section 2 describes AES algorithm modification, and the RSA algorithm combination and the methodology are presented in Section 3. The simulation, experimental and the analyze of the result are presented in Section 4 and 5. By using the hybrid encryption, the encryption speed is effectively improved and the security strength is improved.

The Advanced Encryption Standard (AES), also known as Rijndael, has not been breached at this time. Nonetheless, AES cryptanalysis has not stopped and many researchers are seeking new approaches to allow us to achieve competitive efficiency. To provide a high efficiency and a malleable algorithm for different kind of business needs (e-commerce, emails, bank card...).

The following two modifications to the original AES algorithm have been made in our research:

1) Adding new key: functions are conducted as shown in

Until we do the key expansion stage of the encryption process, the additional key will be XORed with plain text first. XOR’s call this process InitialAddRoundKey. The new output resulting from the operation Initial AddRoundKey is used as plaintext for the following steps. Before that the conventional key is spent to produce the subkeys;

2) Reconfiguration in the SubBytes function: rather than the existing SubBytes operation, we inserted a new operation in the original SubBytes operation, called Modified Transport. And we update SubBytes to this function as ModSubBytes. Next, the data in the ModSubBytes process is transmitted before the values of S-Box have been replaced. The state array is divided into two halves (4 bits each) each part of the State array (a value of 8 bits) and is transferred or exchanged in order to achieve a new state value in the transportation process.

Both the methods of symmetric and asymmetric encryption are used to achieve the information confidentiality [

asymmetric algorithms. AES encryption algorithms cannot implement signatures. RSA can be used to implement electronic signatures. These two types of encryption algorithms have their own advantages and disadvantages [

The implementation process of the encryption algorithm is as follows:

1) The receiver creates the RSA public key and the private key (key pair), the receiver saves the private key, and sends the RSA public key to the sender of the data through the Internet;

2) The data sender creates the extend AES key, encrypts the AES key with the RSA public key sent by the receiver, and encrypts the plaintext data to be sent with the created AES key;

3) After receiving the ciphertext and the encrypted AES key, the receiver decrypts the AES key by using the RSA private key saved by the receiver, and then

decrypts the received ciphertext data with the key to obtain the plaintext data.

In the actual application process, if the data communication parties often send a large amount of data to each other, the encryption comprehensive operation scheme can be further optimized, that is:

1) The AES key exchange is performed by RSA at regular intervals;

2) And after the AES key is exchanged, the two parties send data using the AES key of the other party key.

The specific process is that both the sender and the receiver use RSA to generate a password pair, and send the generated public key to the other party. Each party generates an AES key, and encrypts the AES generated by the other party’s public key and sends it to the other party. After the AES password cipher text encrypted by the RSA public key, the AES password is decrypted by using the respective RSA private key and stored. In a certain period of time, both parties use the other party’s AES to encrypt and send, and the two parties receive each other’s ciphertext and then use the saved AES key to decrypt and obtain the plaintext. When adopting this scheme, the AES key must be re-reconstructed periodically and exchanged, and the probability of password leakage can be greatly reduced by the periodic replacement of the password.

The system implements the encryption scheme combining AES and RSA algorithm, and uses two fixed encryption algorithms to test the encryption algorithm. The time used for encryption and decryption by AES is basically the same. The time used for RSA public key encryption and the AES encryption time are basically the same. The difference is not big, but the time required to decrypt using RSA private key is more, the test result (

In order to test the performance, by transmitting an 11 M size electronic contract document for simulation transmission test, a 128-bit encryption key is first generated on the sender, and the key is encrypted by the RSA asymmetric algorithm and then sent to the receiver for reception. After receiving the contract ciphertext and the symmetric key, the party successfully completed the decryption of the contract, and the combination of decryption takes about 20 seconds. The asymmetric encryption algorithm is used to encrypt the contract. After sending, it is decrypted again. The decryption process takes about 180 seconds. Therefore, the efficiency of using hybrid encryption algorithms is much better than that of asymmetric encryption algorithms. Simulation test (as shown in

It is proved by experiments that the complex encryption algorithm is close to the symmetric key encryption algorithm in terms of running speed. From the test data, the complex encryption algorithm is only 0.8 seconds longer than the

TYPE | Amount of data | Encrypted data (M) | Encryption time (s) | Decryption time (s) |
---|---|---|---|---|

AES | 1 | 2.034 | 0.153 | 0.305 |

5 | 10.172 | 0.763 | 1.525 | |

10 | 101.724 | 3.813 | 15.253 | |

20 | 2034.472 | 19.067 | 305.064 | |

RSA | 1 | 1.001 | 2777.778 | 229,166.667 |

5 | 5.007 | 13,888.889 | 1,145,833.333 | |

10 | 25.035 | 69,444.444 | 11,458,333.333 | |

20 | 125.174 | 347,222.222 | 229,166,666.667 | |

Hybrid encryption | 1 | 2.134 | 0.183 | 0.405 |

5 | 11.172 | 0.963 | 1.895 | |

10 | 109.724 | 4.213 | 16.153 | |

20 | 2087.472 | 19.867 | 315.064 |

symmetric encryption algorithm for 20 M data. For this kind of encryption application, the algorithm can meet the daily use of a large number of applications.

Through experimental tests, the complex encryption algorithm is based on security. The complex encryption algorithm (hybrid encryption) uses AES for the main data. From the perspective of data security, it is safer, and the AES encryption key is through RSA. Encrypted, so the encrypted data is more secure than AES.

Above, we compare our method approach with performance of other methods for that we use a text.txt (

Graph 1. Encryption and decryption time comparison AES standard vs hybrid algorithm.

Methods | #chars | Ciphertext size(kb) | Encryption time(s) | Decryption time(s) |
---|---|---|---|---|

Vigila and Munees [ | 409 | 459.118 | 1.95 | 0.83 |

Dimas, faisal, dewi [ | 409 | 15.587 | 0.263 | 0.206 |

Proposed | 409 | 17.966 | 0.258 | 0.312 |

but we still need to improve our performance by optimizing the decryption 0.312.

For implementation, various encryption techniques require different memory sizes. The needed memory depends on the number of operations the algorithm must perform, the key size used, the vectors used for initialization and the types of operations. Memory used Program Affect Costs [

Graph 2 and

Algorithm | Memory Used(KB) |
---|---|

AES | 14.7 |

RSA | 31.5 |

Hybrid encryption | 17.756 |

Graph 2. Memory consumption comparison.

A popular and classical measure of uncertainty in the theory of knowledge was described in 1948 by (Shannon, 1948) [

Shannon suggested that entropy H(X) could be determined by the average amount of information of a discrete random variable X.

H ( X ) = ∑ i = 1 n p ( x i ) log 2 p ( x i )

on the following terms:

· X consists of a finite of a sample space x 1 , x 2 , x 3 , ⋅ ⋅ ⋅ , x n ;

· P(x_{i}) probability distribution, x i ≥ X ;

· And ∑ i n 1 p ( x i ) .

We present security analyses of the proposed here. Theoretical analysis indicates that the proposed algorithm overcomes security problems, key management problem the key management is easier by bringing in a trustworthy third party [

AES already represents a safe algorithm that goes beyond cryptanalysis. Hackers often aim to find the cryptanalysis cipher key, which can be used to decode cipher text [

key. The question now is how long does it take for brute force to locate the actual key? The time for brute force attack depends on key size. This can be found very easily if the size of the key is small. But if the key size is longer than it can take quite a long time to locate the actual key.

In this paper, the encryption system combining AES and RSA algorithm makes full use of the advantages of symmetric key and asymmetric key. The session key used in the file is encrypted by RSA, and the encryption of data file is encrypted by AES. The system’s encryption processing efficiency is high. The encryption algorithms commonly used in cryptography are analyzed and summarized. The AES encryption algorithm is implemented based on JAVA language. The algorithm is packaged and designed for the mixed use of AES and RSA encryption algorithms, which can reduce the understanding of encryption algorithms. Finally, the system analysis of the commonly used encryption algorithm is carried out. Through the system design of the encryption algorithm, it can help the relevant user.

The authors declare no conflicts of interest regarding the publication of this paper.

Lu, Z.M. and Mohamed, H. (2021) A Complex Encryption System Design Implemented by AES. Journal of Information Security, 12, 177-187. https://doi.org/10.4236/jis.2021.122009