Author: Andrey Galkin

Web Site

About

Node.js implementation of RFC5869: HMAC-based Extract-and-Expand Key Derivation Function (HKDF).

The implementation is fully compliant with test vectors provided in the RFC.

There are alternative modules, but they are:

• much less performing and/or
• have quite poor code quality at the moment and/or
• are not compliant with RFC (e.g. work only with string parameters) and/or
• not working with current Node.js versions and/or
• do not support arbitrary hash functions and/or
• not reliable dependency for FutoIn Security concept in general.

Standalone HKDF extract() and expand() actions are also available for advanced usage.

Performance comparison

The figures in "derived keys per second".

• futoin-hkdf - 74 642
  • fully compliant
• node-hdkf/hdkf modules - 57 707 (~22% slower)
  • seems to be broken by design
  • produces wrong results with RFC test vectors
• ctrlpanel-hdkf - 52 181 (~30% slower)
  • seems to be compliant
• @stablelib/hkdf - 39 808 (~46% slower)
  • seems to be compliant

Installation for Node.js

Command line:

$ npm install futoin-hkdf --save

or:

$ yarn add futoin-hkdf --save

Examples

const hkdf = require('futoin-hkdf');

// Parameter overview
//-------------------
// initial keying material
const ikm = 'string-or-buffer';
// required output length in bytes
const length = 16;
// can be empty string or false equivalent
const salt = 'strongly-encouraged';
// optional parameter
const info = 'optional-context';
// HMAC hashing algorithm to use
const hash = 'SHA-256';

// Generic derivation
//-------------------
hkdf(ikm, length, {salt, info, hash}); // Buffer(length) - derived key
hkdf(ikm, length, {salt, info, hash}).toString('hex'); // String(2*length)

// NOTE: all optional paramaters are passed in object

// With some parameters omitted
//-------------------
hkdf(ikm, length, {salt});
hkdf(ikm, length, {info});
hkdf(ikm, length, {hash});
hkdf(ikm, length);

// Advanced usage (only if you know what you are doing)
//-------------------
hkdf.hash_length(hash); // get hash_len
hkdf.extract(hash, hash_len, ikm, salt); // run only step #1
hkdf.expand(hash, hash_len. prk, length, info); // run only step #2

API documentation

hkdf(ikm, length, salt, info, hash) ⇒ Buffer

HMAC-based Extract-and-Expand Key Derivation Function (HKDF)

Kind: global function
Returns: Buffer - Raw buffer with derived key of @p length bytes

• hkdf(ikm, length, salt, info, hash) ⇒ Buffer
  • .hash_length(hash) ⇒ integer
  • .extract(hash, hash_len, ikm, salt) ⇒ Buffer
  • .expand(hash, hash_len, prk, length, info) ⇒ Buffer

hkdf.hash_length(hash) ⇒ integer

Get expected hash length.

Kind: static method of hkdf
Returns: integer - hash digest byte length
Note: Values are hardcoded with fallback for unknown algorithms.

hkdf.extract(hash, hash_len, ikm, salt) ⇒ Buffer

HKDF extract action.

Kind: static method of hkdf
Returns: Buffer - A buffer with pseudorandom key
Note: Values are hardcoded with fallback for unknown algorithms.

hkdf.expand(hash, hash_len, prk, length, info) ⇒ Buffer

HKDF expand action.

Kind: static method of hkdf
Returns: Buffer - A buffer with output keying material
Note: Values are hardcoded with fallback for unknown algorithms.