Bcrypt vs Scrypt
In-Depth Technical Comparison & Architecture Guide
Bcrypt and Scrypt are designed to secure passwords by slowing down validation. We compare CPU-bound Blowfish stretching against memory-hard blocks.
Quick Reference Matrix
| Feature | Bcrypt | Scrypt |
|---|---|---|
| Resource Focus | CPU-bound | Memory and CPU bound |
| ASIC Resistance | Moderate | High |
| Max Password Limit | 72 bytes | No limit |
Technology Overview
Bcrypt uses a logarithmic cost factor to scale CPU rounds. Scrypt requires both CPU and large memory blocks to calculate digests, preventing ASIC parallel runs.
Memory Hardness and ASIC Chips
Bcrypt is vulnerable to ASIC custom chips because its memory footprint is tiny (~4KB). Scrypt demands configurable memory blocks, making custom chips expensive.
Bcrypt Advantages & Disadvantages
Advantages / Pros
- Highly mature
- Simple configuration
Disadvantages / Cons
- 72-byte truncation
- CPU-only focus
Scrypt Advantages & Disadvantages
Advantages / Pros
- Memory-hard
- Protects against custom ASICs
Disadvantages / Cons
- Complex parameters
- Higher server RAM cost
Real-World Use Cases
Bcrypt
Standard application logins
Securing password tables on typical server configurations.
Scrypt
Cryptocurrency wallets
Hashing master keys that require memory-hardness.
Developer Recommendation
Use Bcrypt for basic web configurations. Use Scrypt or Argon2 if you expect custom hardware brute-force threats.
Frequently Asked Questions
- Why does Bcrypt limit password length?
- Because the Blowfish cipher it relies on is built on a 72-byte key size limit.
Launch Interactive Developer Tools
Put these concepts into practice. Test, format, serialize, or analyze your inputs locally with these secure, browser-only utilities: