def compute_hkdf(ikm, salt):
    """
    Standard hkdf algorithm
    :param {Buffer} ikm Input key material.
    :param {Buffer} salt Salt value.
    :return {Buffer} Strong key material.
    @private
    """
    prk = hmac.new(salt, ikm, hashlib.sha256).digest()
    info_bits_update = info_bits + bytearray(chr(1), 'utf-8')
    hmac_hash = hmac.new(prk, info_bits_update, hashlib.sha256).digest()
    return hmac_hash[:16]
Standard hkdf algorithm
    :param {Buffer} ikm Input key material.
    :param {Buffer} salt Salt value.
    :return {Buffer} Strong key material.
    @private