Bcrypt-PBKDF
OpenBSD’s password-based key derivation function using eksblowfish (expensive key schedule Blowfish). Uses Bcrypt as a cryptographic primitive with iterative hashing for strong key stretching. Different from standard Bcrypt password hashing - designed specifically for key derivation in OpenSSH and other applications.
Properties
| Property |
Value |
| Category |
Key Derivation Functions |
| Sub-category |
Key Derivation Function |
| Security status |
🛡️ Secure |
| Complexity |
Advanced |
| Inventor |
Niels Provos, Ted Unangst |
| Year |
2013 |
| Origin |
🇺🇸 United States |
| Source |
algorithms/kdf/bcrypt-pbkdf.js |
Parameters
| Parameter |
Supported values |
| Output sizes |
1 byte (8 bits) to 1024 bytes (8192 bits) |
Capabilities
| Flag |
Value |
SaltRequired |
Yes |
Security
Status: 🛡️ Secure
Known vulnerabilities
| Issue |
Description |
Mitigation |
| Computational Cost |
While designed to be expensive, modern GPUs can parallelize bcrypt. Use sufficient rounds (32+) for 2025. |
— |
| Side-Channel Timing |
Implementation should use constant-time comparisons for password verification |
— |
Documentation
References
Test vectors
7 vectors ship with this algorithm and run in the test suite. Byte values are hexadecimal.
Vector 1 — Botan Test #1: password/salt, 12 rounds, 32 bytes
| Field |
Value |
salt |
73616c74 |
iterations |
12 |
outputSize |
32 |
input |
70617373776f7264 |
expected |
1ae42c05d487bc02f64921a4ebe4ea93bcacfe135fda99974c06b7b01fae149a |
Vector 2 — Botan Test #2: A/0001020304050607, 10 rounds, 10 bytes
| Field |
Value |
salt |
0001020304050607 |
iterations |
10 |
outputSize |
10 |
input |
41 |
expected |
3c705da7e10c61c2523b |
Vector 3 — Botan Test #3: A/0001020304050607, 10 rounds, 64 bytes
| Field |
Value |
salt |
0001020304050607 |
iterations |
10 |
outputSize |
64 |
input |
41 |
expected |
3cf670095d5fa753e1430c6d6177c299 521b3b614d9e53fa89c7f893f33289f6 77ddd72ee1aa29cbf5574a948de4623c 71996ffd16c8806fdd7acbe02992deac |
Vector 4 — Botan Test #4: password/salt, 3 rounds, 32 bytes
| Field |
Value |
salt |
73616c74 |
iterations |
3 |
outputSize |
32 |
input |
70617373776f7264 |
expected |
ccb508027535a962f591d4a7eea08fe15ee0b68044b1a7b209605fdfbfb41228 |
Vector 5 — Botan Test #5: password/salt, 4 rounds, 16 bytes
| Field |
Value |
salt |
73616c74 |
iterations |
4 |
outputSize |
16 |
input |
70617373776f7264 |
expected |
5bbf0cc293587f1c3635555c27796598 |
Vector 6 — Botan Test #6: password/salt, 8 rounds, 64 bytes
| Field |
Value |
salt |
73616c74 |
iterations |
8 |
outputSize |
64 |
input |
70617373776f7264 |
expected |
e1367ec5151a33faac4cc1c144cd23fa 15d5548493ecc99b9b5d9c0d3b27bec7 6227ea66088b849b20ab7aa478010246 e74bba51723fefa9f9474d6508845e8d |
Vector 7 — Botan Test #7: password/salt, 10 rounds, 32 bytes
| Field |
Value |
salt |
73616c74 |
iterations |
10 |
outputSize |
32 |
input |
70617373776f7264 |
expected |
abc7dcfb41032d844af67a1d1ef8a5e6a04aa3073d4f2777bfa5fe07a54cff9d |
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