HKDF
HMAC-based Key Derivation Function (HKDF) as defined in RFC 5869. Two-step Extract-and-Expand process for deriving cryptographic keys from input keying material using salt and application-specific info parameters.
Properties
| Property |
Value |
| Category |
Key Derivation Functions |
| Sub-category |
Extract-and-Expand KDF |
| Security status |
🎓 Educational Only |
| Complexity |
Intermediate |
| Inventor |
Hugo Krawczyk, Pasi Eronen |
| Year |
2010 |
| Origin |
🇺🇸 United States |
| Source |
algorithms/kdf/hkdf.js |
Parameters
| Parameter |
Supported values |
| Output sizes |
1 byte (8 bits) to 16320 bytes (130560 bits) |
Capabilities
| Flag |
Value |
SaltRequired |
No |
Security
Status: 🎓 Educational Only
Known vulnerabilities
| Issue |
Description |
Mitigation |
| Weak Hash Function |
Use secure hash functions like SHA-256 or SHA-512 instead of SHA-1 or MD5 |
— |
| Insufficient Input Entropy |
Ensure input keying material has sufficient entropy for cryptographic security |
— |
Documentation
References
Test vectors
3 vectors ship with this algorithm and run in the test suite. Byte values are hexadecimal.
Vector 1 — HKDF-SHA256 RFC 5869 Test Case 1
| Field |
Value |
salt |
000102030405060708090a0b0c |
info |
f0f1f2f3f4f5f6f7f8f9 |
outputSize |
42 |
hashFunction |
SHA256 |
input |
0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b |
expected |
3cb25f25faacd57a90434f64d0362f2a 2d2d0a90cf1a5a4c5db02d56ecc4c5bf 34007208d5b887185865 |
Vector 2 — HKDF-SHA256 RFC 5869 Test Case 2 - longer inputs
| Field |
Value |
salt |
606162636465666768696a6b6c6d6e6f 707172737475767778797a7b7c7d7e7f 808182838485868788898a8b8c8d8e8f 909192939495969798999a9b9c9d9e9f a0a1a2a3a4a5a6a7a8a9aaabacadaeaf |
info |
b0b1b2b3b4b5b6b7b8b9babbbcbdbebf c0c1c2c3c4c5c6c7c8c9cacbcccdcecf d0d1d2d3d4d5d6d7d8d9dadbdcdddedf e0e1e2e3e4e5e6e7e8e9eaebecedeeef f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff |
outputSize |
82 |
hashFunction |
SHA256 |
input |
000102030405060708090a0b0c0d0e0f 101112131415161718191a1b1c1d1e1f 202122232425262728292a2b2c2d2e2f 303132333435363738393a3b3c3d3e3f 404142434445464748494a4b4c4d4e4f |
expected |
b11e398dc80327a1c8e7f78c596a4934 4f012eda2d4efad8a050cc4c19afa97c 59045a99cac7827271cb41c65e590e09 da3275600c2f09b8367793a9aca3db71 cc30c58179ec3e87c14c01d5c1f3434f 1d87 |
Vector 3 — HKDF-SHA256 RFC 5869 Test Case 3 - zero-length salt
| Field |
Value |
salt |
(empty) |
info |
(empty) |
outputSize |
42 |
hashFunction |
SHA256 |
input |
0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b |
expected |
8da4e775a563c18f715f802a063c5a31 b8a11f5c5ee1879ec3454e5f3c738d2d 9d201395faa4b61a96c8 |
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