MD5 and SHA Algorithms

Different hash algorithms produce digests of different lengths and security margins. Choosing the wrong one can break interoperability or create a false sense of safety.

MD5 (128-bit)

MD5 is fast and still appears in legacy checksums, cache keys, and older tooling. It is not appropriate for new security-sensitive designs because collision attacks are practical. Keep MD5 for compatibility and inspection, not for proving strong integrity against motivated attackers.

SHA-1 (160-bit)

SHA-1 is mostly legacy today. Git still uses a SHA-1-based object ID format, but many platforms have moved away from SHA-1 for TLS certificates and signatures. Treat SHA-1 like MD5: useful when a spec requires it, weak for new security guarantees.

SHA-256, SHA-384, SHA-512 (SHA-2 family)

These are the common modern defaults:

• SHA-256: default choice for file checksums, content addressing, and many APIs
• SHA-384 / SHA-512: stronger variants required by some standards and platforms

All three are widely supported in browsers through the Web Crypto API.

Practical selection guide

• Verifying a modern download checksum → SHA-256
• Matching a third-party tool that still prints MD5 → MD5
• Meeting a compliance document that names SHA-512 → SHA-512
• Storing passwords → none of these alone; use Argon2, bcrypt, or scrypt

Always confirm algorithm name, hex vs Base64 output, and whether the hash covers raw bytes or UTF-8 text before comparing results.