QR Code
Quick Response Code
A two-dimensional barcode that stores data (URLs, text, contact info) readable by cameras and scanners.
Technical Detail
QR Code is a critical component of information security infrastructure. The Web Crypto API (crypto.subtle) provides browser-native implementations of cryptographic algorithms including AES-GCM, RSA-OAEP, ECDSA, and SHA family hash functions. All operations execute in constant-time to prevent timing attacks. Client-side security processing ensures sensitive data (passwords, keys, encrypted content) never leaves the user's device — a property that cannot be guaranteed by server-side alternatives.
Example
```javascript
// QR Code — Web Crypto API example
const data = new TextEncoder().encode('sensitive data');
const hash = await crypto.subtle.digest('SHA-256', data);
const hex = Array.from(new Uint8Array(hash))
.map(b => b.toString(16).padStart(2, '0')).join('');
```