HKDF Key Derivation Tool (RFC 5869)
HKDF Key Derivation Tool (RFC 5869): Computes PRK = HMAC-Hash(salt, IKM) and expands into cryptographically independent subkeys.
About this hkdf key derivation tool (rfc 5869)
Computes PRK = HMAC-Hash(salt, IKM) and expands into cryptographically independent subkeys Runs entirely in-memory using Web Crypto primitives to keep sensitive tokens, certificates, and cryptographic keys secure from third-party interception.
Encoding & cryptographic principles
Performs symmetric encryption and asymmetric public-key operations adhering to NIST FIPS 197 (AES), RFC 7539 (ChaCha20-Poly1305), RFC 8032 (Ed25519 Digital Signatures), and PKCS#1 / RFC 3447 (RSA). AES-GCM provides authenticated symmetric encryption using 128-bit or 256-bit keys and 96-bit initialization vectors (IVs) to ensure confidentiality and cryptographic authentication. Key derivation employs PBKDF2 (RFC 2898) with HMAC-SHA256 and configurable salt iterations to thwart brute-force dictionary attacks.
Worked verification example
Scenario: Derive 32 bytes with a fixed HKDF-SHA-256 test vector.
Sample input:
Processing: UTF-8 encode ikm, salt and info, then call Web Crypto HKDF deriveBits for 256 bits.
Illustrative output:
Security parameters & input constraints
Requested length is clamped to 1–8160 bytes, but unsupported hashes or invalid Web Crypto lengths can still error. HKDF expands supplied key material; it does not create randomness, secure a weak input secret or store a key.
Cryptographic digests, encoded strings, and signatures generated by HKDF Key Derivation Tool (RFC 5869) should be verified against target authentication systems before production use.
Client-side Web Crypto boundary
Key derivation, hashing, and encoding in HKDF Key Derivation Tool (RFC 5869) execute in local memory using Web Crypto APIs without remote socket transmission.
Cryptographic specifications & RFC standards
Technical specifications and cryptographic RFC standards governing algorithms and key representations:
HKDF Key Derivation Tool (RFC 5869) verification · Audit standards
How to use it
- Enter JSON with input key material (ikm), optional salt/info, hash and output length in bytes.
- Derive bits locally through Web Crypto HKDF; SHA-256 and 32 bytes are defaults.
- Read the selected algorithm, byte length and derived hex in JSON.
Frequently asked questions
Which HKDF fields and limits are implemented?+
It reads JSON ikm, salt, info, hash and length. Text values are UTF-8 encoded; length defaults to 32 bytes and is clamped from 1 through 8160 bytes before Web Crypto deriveBits.
What example can I run locally?+
Enter {"ikm":"input-key-material","salt":"salt","info":"czoa","length":32,"hash":"SHA-256"}. The local result is HKDF-SHA-256 hex 419b4f2512ca4e734c4920b55535f5d55bc937cac4c3f3b8d9382cbde8d389e6.
Does HKDF create a password hash?+
No. HKDF expands input key material into derived bytes for a chosen context. It does not rate-limit guesses, score passwords, store credentials, or replace a password KDF policy.
What assumptions affect the output?+
Changing UTF-8 text, hash, salt, info or requested length changes the bytes. The page does not validate protocol-specific key lifecycle, entropy source of supplied ikm, or secret handling outside this browser operation.