core/library/sodium-plus/docs/SodiumPlus/key-derivation.md

Key derivation

See also: Libsodium's documentation on its key derivation features.

crypto_kdf_derive_from_key

Derive a subkey from a master key.

Parameters and their respective types:

1. {number} output length (typically you want 32)
2. {number} subkey ID
3. {string|Buffer} context (must be a string/buffer of length 8)
4. {CryptographyKey} master key

Returns a Promise that resolves to a CryptographyKey.

crypto_kdf_keygen

Returns a CryptographyKey object containing a key appropriate for the crypto_kdf API.

Example for crypto_kdf

const { SodiumPlus } = require('sodium-plus');
let sodium;

(async function () {
    if (!sodium) sodium = await SodiumPlus.auto();
    let masterKey = await sodium.crypto_kdf_keygen();
    let context = 'Sodium++';

    let subkey1 = await sodium.crypto_kdf_derive_from_key(32, 1, context, masterKey);
    let subkey2 = await sodium.crypto_kdf_derive_from_key(32, 2, context, masterKey);
    let subkey3 = await sodium.crypto_kdf_derive_from_key(32, 3, context, masterKey);
    
    console.log({
        'master-key': masterKey.getBuffer().toString('hex'),
        'subkey1': subkey1.getBuffer().toString('hex'),
        'subkey2': subkey2.getBuffer().toString('hex'),
        'subkey3': subkey3.getBuffer().toString('hex')
    });
})();