Comparing Hash Algorithms
Choose the right hash function for your use case: security, performance, and compatibility.
Quick Decision Guide
General Purpose Security → SHA-256
File integrity, digital signatures, certificates, blockchain. Universally supported, fast, and secure.
Password Hashing → Argon2 or bcrypt
Specialized algorithms designed to resist brute-force attacks. Intentionally slow and memory-hard.
High Performance → BLAKE3
Faster than SHA-256 with parallel processing support. Great for large files and high-throughput systems.
Maximum Security Margin → SHA-3
Different internal structure from SHA-2. Use when you want defense-in-depth or future-proofing.
Detailed Comparison
| Algorithm | Output Size | Speed | Security | Status |
|---|---|---|---|---|
| MD5 | 128 bits | Fast | Broken | Deprecated |
| SHA-1 | 160 bits | Fast | Broken | Deprecated |
| SHA-256 | 256 bits | Fast | Strong | Recommended |
| SHA-512 | 512 bits | Fast (64-bit) | Strong | Recommended |
| SHA-3-256 | 256 bits | Moderate | Strong | Recommended |
| BLAKE2b | 256-512 bits | Very Fast | Strong | Recommended |
| BLAKE3 | 256 bits | Fastest | Strong | Recommended |
SHA-2 Family (SHA-256, SHA-512)
Strengths
- +Universally supported across all platforms
- +Hardware acceleration in modern CPUs
- +Extensively analyzed, no known attacks
- +Required by many standards (TLS, Bitcoin)
- +Fast on both 32-bit and 64-bit systems
Weaknesses
- −Length extension attacks (use HMAC to mitigate)
- −Slower than BLAKE2/BLAKE3
- −Same internal structure as broken SHA-1
Digital signatures, SSL/TLS certificates, blockchain applications, file integrity verification, general-purpose cryptographic hashing where compatibility is important.
SHA-512 is often faster than SHA-256 on 64-bit systems because it uses 64-bit operations. If you don't need the smaller output size, SHA-512 can be a better choice for performance.
SHA-3 Family
Strengths
- +Completely different design from SHA-2
- +No length extension vulnerability
- +Large security margin
- +Flexible output length (SHAKE variants)
- +Official NIST standard (2015)
Weaknesses
- −Slower than SHA-256 in software
- −Less hardware acceleration support
- −Not as widely adopted yet
Applications requiring defense-in-depth (using both SHA-2 and SHA-3), future-proofing against potential SHA-2 vulnerabilities, systems that need variable-length output (SHAKE128/256).
If SHA-2 is ever broken, SHA-3's different design means it won't be affected. Use SHA-3 when you want maximum security margin or when building systems that need to remain secure for decades.
BLAKE2 and BLAKE3
Strengths
- +Faster than MD5 while being secure
- +BLAKE3 supports parallel hashing
- +Built-in keyed hashing (MAC mode)
- +Simpler implementation than SHA-2/3
- +Excellent performance on all platforms
Weaknesses
- −Less standardization than SHA family
- −Not required by any major standards
- −Smaller ecosystem of tools
High-performance applications, content-addressable storage, checksumming large files, systems where speed is critical but security cannot be compromised.
BLAKE3 can hash data at multiple GB/s on modern CPUs, making it ideal for:
- -Hashing large files (videos, disk images, backups)
- -Real-time data integrity in high-throughput systems
- -Content-addressable storage (like Git, but faster)
Password Hashing Algorithms
Never use fast hash functions (SHA-256, BLAKE3, etc.) for password hashing. Passwords need specialized algorithms designed to be slow and memory-intensive to resist brute-force attacks.
Argon2 (Recommended)
Winner of the Password Hashing Competition (2015). Resistant to GPU and ASIC attacks through memory-hardness.
bcrypt
Older but still secure. Based on Blowfish cipher. Widely supported and battle-tested since 1999.
scrypt
Memory-hard function designed to resist hardware attacks. Used by some cryptocurrencies.
PBKDF2 (Legacy)
Still acceptable but not recommended for new systems. Vulnerable to GPU acceleration.
Use Case Recommendations
File Integrity Verification
Recommended: SHA-256 or BLAKE3
SHA-256 for compatibility, BLAKE3 for speed. Both provide strong collision resistance.
Digital Signatures
Recommended: SHA-256 or SHA-512
Required by most signature standards (RSA, ECDSA). SHA-512 for 256-bit security level.
Password Storage
Recommended: Argon2id
Use bcrypt if Argon2 isn't available. Configure with appropriate cost parameters.
Message Authentication (HMAC)
Recommended: HMAC-SHA-256 or BLAKE2 (keyed mode)
BLAKE2 has built-in keyed hashing. SHA-256 with HMAC is more standardized.
Content-Addressable Storage
Recommended: BLAKE3 or SHA-256
BLAKE3 for performance, SHA-256 for compatibility with existing systems (like Git).
Blockchain/Cryptocurrency
Recommended: SHA-256 (Bitcoin) or Keccak-256 (Ethereum)
Follow the standard for your specific blockchain. Bitcoin uses double SHA-256.
Performance Benchmarks
Note: Actual performance varies by CPU, implementation, and data size. Hardware acceleration can significantly improve speeds.
The Bottom Line
Use SHA-256 unless you have a specific reason to choose something else. It's secure, fast, universally supported, and required by many standards. For passwords, use Argon2id. For high-performance applications, consider BLAKE3.
Official Resources
Hash Function Standards
- → NIST FIPS 180-4: SHA-2 Family (SHA-256, SHA-512) (NIST)
- → NIST FIPS 202: SHA-3 Family (NIST)
- → RFC 7693: BLAKE2 Specification (IETF)
- → BLAKE3 Specification (Official)
Password Hashing Standards
- → RFC 9106: Argon2 Memory-Hard Function (IETF)
- → RFC 7914: scrypt Password-Based KDF (IETF)
- → RFC 8018: PBKDF2 Specification (IETF)
Security Guidelines
- → NIST SP 800-63B: Digital Identity Guidelines (NIST)
- → OWASP Password Storage Cheat Sheet (OWASP)
- → NIST Hash Functions Project (NIST)