The best solution to protect our data from cryptanalysis is through cryptography. As electronic connectivity has made significant progress, there is a need to secure information by cryptography. With the rapid growth of technology, encryption is the most powerful approach to strengthening security and preserving privacy. The main aim of encryption techniques is to secure the data and provide confidentiality, integrity, and authenticity
Is one of the classical encryption techniques in which the characters present in the original text are replaced by other characters. The substitution techniques can be classified as follows: Caesar cipher
Is another classical encryption technique in which the order of alphabets in the plaintext is rearranged to form a cipher text. The bits of plain text are permuted to other places to give cipher text. The transposition techniques can be classified as follows: The RailFence technique and columnar transposition cipher
Using classical encryption techniques, researchers proposed various algorithms
The study and review of previous research on substitution and transposition techniques
The ciphertext is so simple that the attackers could quickly identify it.
These existing techniques are vulnerable to brute force attacks, relative frequency, and known plain text.
They do not attain a high level of security.
They take more encryption and decryption time, allowing the attackers to analyze the key.
The NIST defines computer security
There are three basic steps to send secret information to the authorized user over a noisy channel. (1) Encrypting the plaintext into an unreadable format called ciphertext. (2) Sending the information over a noisy channel. (3) Decrypting the ciphertext to text using a secret key. These steps will provide secure communication to the users.
This cryptosystem uses a hybrid strategy built on substitution cipher and transposition cipher to increase security and make it harder to decrypt for cryptanalysts. We are using two of the traditional encryption approaches to increase the speed and effectiveness of the encryption and decryption mechanism. This technique uses two keys, one representing the plaintext length and the other the deleted bit length. We propose this cryptosystem based on encryption methods that remove some bits from plain text and permute them in another location to increase security. This system is secure against structural attacks. The ERN Cryptosystem's encryption mechanism's flowchart is depicted in
Plain text = EVERY DAY IS A CHANGE TO BE BETTER
Step 1 Converting the text into binary form
010001010101011001000101010100100101
100101000100010000010101100101001001
010100110100000101000011010010000100
000101001110010001110100010101010100
010011110100001001000101010000100100
010101010100010101000100010101010010
Step 2
Key 1 = 010001010110010101100101010001
000001100101010101010000000011100001
010100010001000101010001110100010001
000010010101000101010001010010
Key 2 = 010101000100100100010101001000
1101010100000011101101010100110010010
10100010101000101
Step 3 Dividing Key1 and Key2 into three equal parts
C = 01000101011001010110010101000100000110010101
D = 01010100000000111000010101000100010001010100
E = 01110100010001000010010101000101010001010010
F = 0101010001001001000101010010
G = 0011010101000000111011010101
H = 001100100101010001010100010
Step 4 Concatenating C with H, D with G, and E with F respectively
Concatenate = 01110100010001000010010
10100010101000101001000110010010101
00010101000101010101000000001110000
10101000100010001010100001101010100
00001110110101010100010101100101011
00101010001000001100101010101010001
001001000101010010
Step 5 Converting binary form into hexadecimal form
Ciphertext = 744425454523254545540385444543540ED5456565
441955449152
Step 6 End
Decryption Process
Step 1 Calculating the length of Key1 and Key2 and storing as A and B respectively
A = 132
B = 84
Step 2 Converting the ciphertext into binary form
01110100010001000010010101000101010
00101001000110010010101000101010001
01010101000000001110000101010001000
10001010100001101010100000011101101
01010100010101100101011001010100010
00001100101010101010001001001000101
010010
Step 3 First A/3 bits are E, next B/3 bits are H, next A/3 bits are D, next B/3 bits are G, next A/3 bits are C, and next B/3 bits are F respectively
C = 01000101011001010110010101000100000110010101
D = 01010100000000111000010101000100010001010100
E = 01110100010001000010010101000101010001010010
F = 0101010001001001000101010010
G = 0011010101000000111011010101
H = 001100100101010001010100010
Step 4 Writing the Key 1 and Key 2 by concatenating C, D, E and F, G, H respectively
Key 1 = 0100010101100101011001010100
0100000110010101010101000000001110
0001010100010001000101010001110100
0100010000100101010001010100010100
10
Key 2 = 010101000100100100010101001
0001101010100000011101101010100110
01001010100010101000101
Step 6 Inserting 4 bits from Key 2 after every 6 bits of Key 1 and writing the string by converting it into text form
Decrypted Text = EVERYDAYISACHANGETOBEBETTER
Step 7 End
Here, we have taken EVERY DAY IS A CHANGE TO BE BETTER as plaintext. On applying various steps of the encryption process to the given plaintext, we obtain ciphertext as 744425454523254545540385444543540ED5456565441955449152. After using various steps of the decryption process to the received ciphertext, we have reobtained the plaintext: EVERY DAY IS A CHANGE TO BE BETTER.
This section focuses on the time complexity and efficiency of the ERN Cryptosystem, as given before, and compares it with the algorithm based on 2's complement method




1 
96 
0.077 
0.091 
2 
184 
0.082 
0.111 

216 
0.084 

4 
336 
0.088 
0.136 
5 
360 
0.095 
0.138 
The Encoding and Decoding time taken by the ERN Cryptosystem and algorithm based on 2's complement method for five different size input files is depicted in
This study has proposed a hybrid technique for encryption and decryption using classical encryption techniques. In this technique, we have secured the data by making ciphertext stronger than the existing algorithms. We examine the encryption and decryption times of various plaintexts of various sizes and compare the proposed ERN Cryptosystem with an algorithm based on 2's complement method. A comparison table of encoding and decoding time of both the algorithms and the relevant graph of the comparison table is given. The experimental analysis shows that the proposed cryptosystem has better performance and efficiency than the algorithm based on 2's complement method. It can be used for any variable length of the text and resists brute force and relative frequency attacks. Thus, this technique is secure and efficient and can be implemented for lowscale purposes. This cryptosystem is valid only for textual data. In the future, we will improve our cryptosystem by encrypting both image and textual data using permutation techniques.
This research did not receive any specific grant from funding agencies in the public, commercial, or notforpublic sectors.