bcrypt is a password-hashing choice for applications that must verify passwords without storing them in plain text. It turns a supplied password into a hash, then checks a later login by recalculating and comparing that value. Its deliberate computational cost makes large-scale password guessing more expensive than with older weak choices such as MD5. section 3.8 section 8.12
A hash alone is not enough protection against precomputed password guesses. Generate a different salt for every password and store it with that password’s hash. Add a pepper held outside the database, such as in configuration, so a database leak does not give an attacker every input needed to reproduce hashes. section 8.12
Use bcrypt as part of a practical credential-handling flow:
- Generate a fresh salt when creating or changing each password. section 8.12
- Hash the password with bcrypt and save the resulting hash and salt rather than the password itself. section 3.8 section 8.12
- Keep a pepper outside the database and include it consistently when hashing and checking passwords. section 8.12
- On login, hash the supplied password with the same inputs and compare the recalculated value with the stored hash. section 3.8 section 8.12
- Raise bcrypt’s configured cycle count as available computing power grows, while pairing password storage with rate limiting, CAPTCHA, and MFA against online guessing. section 8.12 section 8.17
Password check with a salt and pepper
A Ruby flow generates a bcrypt salt, reads a pepper from an environment variable, and hashes the combined values. To verify a login, it repeats the same calculation and compares the result with the saved hash. The salt remains available with the hash; the pepper remains outside the database. section 8.12
require 'bcrypt' def hash_password(password) salt = BCrypt::Engine.generate_salt pepper = ENV['PEPPER'] hashed_password = BCrypt::Engine.hash_secret( pepper + password + salt, salt) return [hashed_password, salt] end def check_password(password, hashed_password, salt) pepper = ENV['PEPPER'] recalculated_hash = BCrypt::Engine.hash_secret( pepper + password + salt, salt) return hashed_password == recalculated_hash end
Inspect a compact Ruby implementation of hash_password and check_password, including salt generation, environment-based pepper retrieval, and hash comparison. section 8.12
bcrypt reduces the damage of a password-hash leak, but it does not make weak or reused passwords safe. Favor long, complex passwords, protect login and reset endpoints from brute-force attempts, and avoid account-existence leaks by calculating a supplied-password hash even when no matching account exists. section 3.8 section 8.17
