SHA-1 vs SHA-256 vs SHA-512: Which Should You Use?
SHA Family Overview
The Secure Hash Algorithm (SHA) family includes several versions, each with different output sizes and security levels.
SHA-1
Specifications
- Output Size: 160 bits (40 hex characters)
- Block Size: 512 bits
- Rounds: 80
Security Status
SHA-1 is considered cryptographically broken. In 2017, researchers demonstrated a practical collision attack (SHAttered).
Should You Use It?
- No for security-sensitive applications
- Acceptable for non-cryptographic purposes (checksums, identifiers)
- Git uses SHA-1 for commit hashes (being migrated to SHA-256)
SHA-256
Specifications
- Output Size: 256 bits (64 hex characters)
- Block Size: 512 bits
- Rounds: 64
Security Status
Currently secure with no known practical attacks. Part of the SHA-2 family.
Use Cases
- SSL/TLS certificates
- Bitcoin and cryptocurrencies
- Code signing
- File integrity verification
- General-purpose secure hashing
Performance
Faster than SHA-512 on 32-bit systems. Good balance of security and speed.
SHA-384
Specifications
- Output Size: 384 bits (96 hex characters)
- Based on: SHA-512 (truncated)
Use Cases
- When you need more security than SHA-256 but smaller output than SHA-512
- Government and enterprise applications
SHA-512
Specifications
- Output Size: 512 bits (128 hex characters)
- Block Size: 1024 bits
- Rounds: 80
Security Status
Very secure with highest security margin in the SHA-2 family.
Use Cases
- Maximum security applications
- As a base for password hashing (bcrypt, etc.)
- Long-term data integrity
Performance
Faster than SHA-256 on 64-bit systems due to 64-bit operations.
Quick Comparison Table
| Algorithm | Output | Security | Speed (64-bit) | Recommendation |
|-----------|--------|----------|----------------|----------------|
| SHA-1 | 160 bits | Broken | Fast | Avoid |
| SHA-256 | 256 bits | Secure | Medium | General use |
| SHA-384 | 384 bits | Secure | Medium | Enterprise |
| SHA-512 | 512 bits | Very Secure | Fast | High security |
Which Should You Choose?
For General Purpose
SHA-256 - Industry standard, widely supported, secure.
For Maximum Security
SHA-512 - Larger security margin, actually faster on modern 64-bit CPUs.
For Legacy Systems
Consider migration from SHA-1 to SHA-256. The transition is usually straightforward.
For Password Hashing
Don't use raw SHA algorithms! Use bcrypt, scrypt, or Argon2 which incorporate salting and key stretching.
The Future: SHA-3
SHA-3 (Keccak) is the newest member, using a completely different design:
- Not vulnerable to same attacks as SHA-2
- Serves as a backup if SHA-2 is ever compromised
- Adoption is growing but SHA-256/512 remain standard