Caesar Cipher Web Implementation

Introduction:

The provided program is a web-based implementation of the Caesar Cipher, a simple substitution cipher technique. It allows users to encrypt and decrypt messages using a specified shift value. The program uses HTML for the structure, CSS for styling, and JavaScript for the logic behind the encryption and decryption processes.

Overview:

The Caesar Cipher is a basic encryption algorithm where each letter in the plaintext is shifted a certain number of places down or up the alphabet. In this implementation, the user can input a plain text and a shift value, and the program will generate the corresponding encrypted or decrypted text.

Time Complexity:

The time complexity of both the encryption and decryption functions is O(n), where n is the length of the input text. This is because the algorithm iterates through each character of the input text exactly once, performing constant-time operations for each character.

Best for:

This program is suitable for educational purposes, introductory cryptography exploration, or simple cases where a lightweight encryption method is needed. It's best suited for scenarios where security requirements are not high, as the Caesar Cipher is vulnerable to brute-force attacks due to its limited number of possible keys.

Not a Good Practice:

The Caesar Cipher is considered insecure for real-world applications due to its susceptibility to brute-force attacks. It has a fixed and small number of possible keys (26 in the case of the English alphabet), making it easy for an attacker to try all possible combinations.

Steps of Algorithm:

User Input:

• Accepts the plain text and shift value from the user through HTML input elements.

Encryption Function (encrypt()):

• Converts the plain text to uppercase for consistency.
• Iterates through each character of the plain text.
• Checks if the character is an uppercase letter.
• Applies the Caesar Cipher formula to encrypt the letter.
• Leaves non-alphabetic characters unchanged.
• Displays the encrypted text as the result.

Decryption Function (decrypt()):

• Converts the cipher text to uppercase for consistency.
• Iterates through each character of the cipher text.
• Checks if the character is an uppercase letter.
• Applies the reverse Caesar Cipher formula to decrypt the letter.
• Leaves non-alphabetic characters unchanged.
• Displays the decrypted text as the result.

Note:

The decryption function uses the modulo operation to handle cases where the shift goes beyond the bounds of the alphabet, ensuring a valid output.