nl_tokens: HMAC - based Extract - and - Expand Key Derivation Function ( HKDF )
pl_tokens: function hkdf ( ikm , <mask> , { salt = '' , info = '' , hash = 'SHA-256' } = { } ) { hash = hash . toLowerCase ( ) . replace ( '-' , '' ) ; // 0. Hash length const hash_len = hash_length ( hash ) ; // 1. extract const prk = hkdf_extract ( hash , hash_len , ikm , salt ) ; // 2. expand return hkdf_expand ( hash , hash_len , prk , length , info ) ; }