Understanding Character Encoding

The Importance of UTF-8

UTF-8, the current web standard, can represent almost all characters worldwide. It supports all languages including Japanese, Chinese, Korean, and Arabic while maintaining ASCII compatibility.

Benefits:

• Widely adopted as global standard
• Efficient variable-length encoding
• Full ASCII compatibility
• Error detection capability

Causes and Solutions for Character Corruption

Character corruption occurs due to encoding mismatches. Main causes:

1. Encoding mismatch between save and read
2. Missing or incorrect metadata
3. Legacy system compatibility issues

Solutions:

• Always use UTF-8
• Proper BOM handling
• Accurate Content-Type headers
• Use encoding detection tools

Utilizing Regular Expressions

Regular expressions are powerful tools for text processing, useful for pattern matching, replacement, and validation.

Basic Patterns:

• \d+ - Sequence of digits
• \w+ - Sequence of word characters
• ^...$ - Line start and end
• (...)\1 - Duplicate detection with backreference

Difference Between Encryption and Hashing

Encryption

Encryption is reversible - original data can be recovered with a key. Used for protecting confidential information.

Use cases:

• Password-protected files
• Secure communication (HTTPS)
• Personal data in databases

Main methods:

• AES-256: Current encryption standard
• RSA: Public key cryptography
• ChaCha20: High-speed encryption

Hashing

Hashing is irreversible - original data cannot be recovered. Used for data integrity and password storage.

Use cases:

• Secure password storage
• File integrity checks
• Digital signatures

Main methods:

• SHA-256: Secure and widely used
• bcrypt: Password-specific
• MD5: Legacy (deprecated)

XSS Prevention and Sanitization

Proper handling of user input is crucial in web applications.

Basic principles:

1. Input validation (whitelist approach)
2. Output escaping (context-dependent)
3. Content Security Policy (CSP) implementation