Try It Yourself - SyntaxStudy Editor

HTML / CSS / JS

<?php
// Demonstrating CIA triad concepts in code

// --- CONFIDENTIALITY: encrypt sensitive data at rest ---
$plaintext = 'user credit card: 4111-1111-1111-1111';
$key       = random_bytes(32);   // 256-bit key
$iv        = random_bytes(16);   // 128-bit IV for AES-CBC

$ciphertext = openssl_encrypt($plaintext, 'AES-256-CBC', $key, OPENSSL_RAW_DATA, $iv);
$encoded    = base64_encode($iv . $ciphertext); // store IV with ciphertext
echo "Encrypted: $encoded
";

// --- INTEGRITY: hash-based message authentication code (HMAC) ---
$message   = json_encode(['user_id' => 42, 'action' => 'transfer', 'amount' => 500]);
$secretKey = bin2hex(random_bytes(32));
$hmac      = hash_hmac('sha256', $message, $secretKey);

// Verify on receipt
$incoming = $message;
$expected = hash_hmac('sha256', $incoming, $secretKey);
if (hash_equals($expected, $hmac)) {
    echo "Integrity check passed
";
} else {
    echo "WARNING: message tampered
";
}

// --- AVAILABILITY: rate-limit login attempts ---
function checkRateLimit(string $ip, int $maxAttempts = 5, int $windowSeconds = 300): bool
{
    // Pseudo-code using a cache/Redis counter
    $key     = "login_attempts:$ip";
    $current = cache()->increment($key);
    if ($current === 1) {
        cache()->expire($key, $windowSeconds);
    }
    return $current <= $maxAttempts;
}