In PHP, what considerations should be taken into account when implementing a basic encryption algorithm for educational purposes, similar to a Caesar cipher?

When implementing a basic encryption algorithm like a Caesar cipher in PHP for educational purposes, it is important to consider the key used for encryption, the handling of special characters, and the overall security limitations of the algorithm. Additionally, ensuring that the encryption and decryption functions are properly implemented and tested is crucial for understanding the underlying principles of encryption. 

<?php
function caesarCipherEncrypt($text, $shift) {
    $result = "";
    $text = strtoupper($text);
    $length = strlen($text);
    
    for ($i = 0; $i < $length; $i++) {
        if ($text[$i] >= 'A' && $text[$i] <= 'Z') {
            $result .= chr((ord($text[$i]) + $shift - 65) % 26 + 65);
        } else {
            $result .= $text[$i];
        }
    }
    
    return $result;
}

function caesarCipherDecrypt($text, $shift) {
    return caesarCipherEncrypt($text, 26 - $shift);
}

// Example usage
$text = "HELLO WORLD";
$shift = 3;
$encryptedText = caesarCipherEncrypt($text, $shift);
echo "Encrypted Text: " . $encryptedText . "\n";
$decryptedText = caesarCipherDecrypt($encryptedText, $shift);
echo "Decrypted Text: " . $decryptedText . "\n";
?>

Keywords

PHP encryption algorithm Caesar cipher security.

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