What is a Hash?

A hash is a fixed-length string of characters generated from input data using a hash function. Cryptographic hash functions are one-way, meaning the original input cannot be reconstructed from the hash.

When to Use Hashes

• Verifying file integrity (checksums)
• Generating API signatures
• Password hashing reference
• Data fingerprinting and deduplication

Algorithm Differences

• MD5: 128-bit hash (legacy, not collision-resistant)
• SHA-1: 160-bit hash (deprecated for security)
• SHA-256: 256-bit hash (current standard)
• SHA-512: 512-bit hash (maximum security)

Examples

Example: "Hello World" → SHA-256 → a591a6d40bf420404a011733cfb7b190d62c65bf0bcda32b57b277d9ad9f146e