What is the 72-byte truncation limit in Bcrypt?

The Blowfish cipher key schedule caps password inputs at 72 bytes. Characters beyond byte 72 are ignored. Production systems often pre-hash passwords using SHA-256 to accept arbitrary length passphrases.

Why does the same password generate a completely different Bcrypt hash each time?

Bcrypt generates a fresh 128-bit cryptographically secure pseudo-random salt on each run, resulting in a unique ciphertext digest that protects against rainbow table lookups.

What is the difference between $2a$, $2b$, and $2y$ hash prefixes?

$2b$ is the modern bug-fixed Blowfish implementation used across Node.js, Go, Python, and Ruby. $2a$ is the legacy format and $2y$ is a PHP-specific patch.

Are my passwords or hashes transmitted over the internet with this tool?

No. All hashing and verification logic executes 100% locally in your browser using client-side JavaScript. Zero credentials leave your device.

100% Client-SideBlowfish Cryptography • Salt Rounds 4–14 • Constant-Time Verify

Bcrypt Hash Generator & Verifier

Generate cryptographically secure Bcrypt password hashes ($2a, $2b) with configurable salt cost rounds (4–14), verify plaintext passwords against existing database digests, and deconstruct Blowfish hash anatomy without cloud transmission.

Plaintext Password or Secret

Work Factor / Salt Rounds: 10

2^10 = 1,024 iterations

Rounds 4 (Fastest / Testing)Rounds 10–12 (OWASP Standard)Rounds 14 (High Security)

Cryptographic Bcrypt Hash (Cost: 10)Computed in 106ms

Bcrypt Hash Anatomy & Structure:

Prefix

$2b$

Bcrypt format identifier

Cost Factor

$10$

1024 iterations

Salt (22 chars)

2NkYutfFE5NoXrqyK0/.We

128-bit random CSPRNG

Ciphertext (31 chars)

3Lrq410SRt8NKLerMTfG0TEep6bJZz6

Blowfish derived hash

How Bcrypt Protects User Credentials Against Data Breaches

Bcrypt is an adaptive cryptographic key derivation function based on the Blowfish cipher, designed specifically to resist hardware-accelerated brute force attacks.

Cryptographic Salt Generation

A 128-bit cryptographically secure random salt is generated and prepended to the plaintext password, permanently thwarting rainbow table lookup tables.

Eksblowfish Key Schedule

The expensive key schedule (Eksblowfish) executes 2^cost expansion iterations, making offline cracker attacks exponentially expensive.

Self-Contained Storage String

The resulting 60-character string encodes the algorithm identifier, work factor, random salt, and checksum in a single modular column for easy database storage.

Constant-Time Verification

Hash comparisons extract the salt and work factor from the stored string, recompute the Blowfish digest, and verify equality using constant-time algorithms to prevent timing attacks.

Bcrypt Cost Factor (Rounds) vs Computational Work Benchmarks

Rounds (Cost)	Key Expansions (2^N)	Server Hash Time (approx)	Target Workload	OWASP & Security Status
4 – 8	16 – 256 iterations	< 5 ms	Unit test suites, CI/CD automated test runs	Insecure for production passwords
10	1,024 iterations	60 – 100 ms	Standard web applications, microservices	Production standard baseline
12	4,096 iterations	250 – 400 ms	Fintech, healthcare, administrative dashboards	OWASP Recommended Baseline (2024–2026)
14	16,384 iterations	1.2 – 1.8 seconds	Master API keys, privileged root credentials	High latency; use background worker queue
16	65,536 iterations	5 – 8 seconds	Cold storage key derivation, offline vaults	Impractical for interactive web logins

Password Hashing Algorithms: Bcrypt vs Argon2id vs PBKDF2 vs Scrypt vs SHA-256

Algorithm	Hardness Type	GPU / ASIC Resistance	Max Password Length	OWASP / NIST Recommendation
Bcrypt	CPU-hard (Blowfish memory schedule)	High (S-Box cache contention)	72 bytes	OWASP Approved & Highly Recommended
Argon2id	Memory-hard & CPU-hard	Maximum (Memory saturation)	Unlimited	PHC Winner & Top OWASP Standard
PBKDF2	CPU-hard (HMAC iterations)	Low (Easily parallelized on GPUs)	Unlimited	NIST Legacy Approved (Requires 600k+ iterations)
Scrypt	Memory-hard & CPU-hard	High	Unlimited	Recommended alternative (IETF RFC 7914)
SHA-256 / MD5	General purpose cryptographic digest	Zero (Billions of hashes/sec on GPUs)	Unlimited	Prohibited for password storage