Bcrypt Hash Generator & Password Verifier (Custom Salt Rounds)

Bcrypt is a battle-tested password hashing function designed by Niels Provos and David Mazières based on the Blowfish cipher. It remains the industry standard for securely storing user authentication credentials across modern web development stacks, including Node.js, Python, Ruby, Java, and Go.

Unlike general cryptographic digest algorithms like SHA-256 or MD5, which compute in nanoseconds and are highly vulnerable to hardware-accelerated GPU cracking, bcrypt is intentionally computationally expensive. It incorporates a configurable cost factor that exponentially increases the work required to hash passwords.

This Bcrypt Generator and Verifier allows software engineers, system administrators, and security auditors to generate secure bcrypt hashes and test password matches directly in browser memory. You can adjust salt cost rounds from 4 to 14, inspect modular crypt format segments, and verify hashes safely.

To compute standard fast digest algorithms like SHA-256 or HMAC signatures, visit our hash generator. For creating cryptographic identification keys, use the uuid generator.

Step-by-step practical guide

1. Select the Hash Generator tab to create a new bcrypt password hash.
2. Enter your plain text password into the input field.
3. Adjust the Cost Factor / Salt Rounds slider (rounds 10 to 12 represent standard production security baselines).
4. Select the identifier prefix ($2b$ is recommended for modern systems; $2a$ and $2y$ are supported for legacy compatibility).
5. Click Generate Bcrypt Hash to execute key derivation locally.
6. Copy the 60-character hash string or inspect individual segments: algorithm prefix, cost factor, salt, and ciphertext digest.
7. Switch to the Hash Verifier tab to test whether a candidate password matches an existing bcrypt hash string.

Engineering specifications and execution details

Implements the Eksblowfish (Expensive Key Schedule Blowfish) key derivation schedule with data-dependent key expansions.

Generates 128-bit cryptographically secure pseudorandom salt values using window.crypto.getRandomValues.

Encodes outputs in the standard Modular Crypt Format: $[prefix]$[cost]$[22-character salt][31-character digest].

Work factor formula: Hashing cost scales as 2^[cost] iterations of the core Blowfish state expansion.

Strictly adheres to the 72-byte maximum password length specification defined by the canonical bcrypt standard.

Provides constant-time string comparison in verification mode to protect against side-channel timing attacks.

Data privacy and memory isolation

100% in-browser processing: Passwords and generated hashes are calculated entirely within local browser memory.

Zero network transmissions: No credentials ever traverse the internet or get logged in remote server access logs.

Safe for generating testing passwords, validating administrative credentials, and demonstrating security concepts.

Common production use cases

• Backend developers generating initial administrator account password hashes for database seeding scripts.
• System administrators resetting locked user accounts directly in SQL databases without exposing passwords.
• Security researchers testing authentication edge cases and analyzing the computation time trade-offs of various cost factors.

Edge cases and operational boundaries

• Password truncation at 72 bytes: Bcrypt considers only the first 72 bytes of any password input. Characters beyond 72 bytes do not alter the resulting hash, making pre-hashing with SHA-256 a common design pattern for extra-long passphrases.
• Null byte handling: Certain older implementations truncated strings at the first null byte; modern $2b$ prefixes guarantee full 72-byte fidelity.