SHA-1 vs SHA-256
Differences, use cases, and when to use each
SHA-1 (160-bit) has been deprecated for security use after practical collision attacks were demonstrated in 2017. SHA-256 (256-bit) remains secure and is the recommended replacement.
Quick Comparison
| Feature | SHA-1 | SHA-256 |
|---|---|---|
| Hash Size | 160-bit (40 hex chars) | 256-bit (64 hex chars) |
| Security | Deprecated (collisions demonstrated) | Secure |
| Git Usage | Used by Git (being migrated) | Git's migration target |
| Certificate Usage | Rejected by browsers since 2017 | Current standard |
When to Use Each
When to Use SHA-1
Avoid SHA-1 for new applications. It's only acceptable in legacy systems being migrated, and in Git (which is transitioning to SHA-256).
When to Use SHA-256
Use SHA-256 as the default hash function for all new applications. It's secure, widely supported, and the recommended standard by NIST.
Pros & Cons
SHA-1
Faster than SHA-256
Shorter output
Deprecated for security
Collision attacks demonstrated
SHA-256
Cryptographically secure
NIST recommended
Long-term security
Slightly slower
Longer hash strings
Verdict
Always use SHA-256 over SHA-1. SHA-1 is deprecated by NIST, rejected by browsers, and has demonstrated collisions. The performance difference is negligible.