Digital Signature 27 (2) Every licensed certification authority shall immediately notify the Commission of any amendment or alteration to any information or document which has been furnished to the Commission in connection with the licence. Requirements as to advertisement 26. A licensed certification authority shall not publish, whether in a newspaper, brochure or otherwise, any advertisement or information relating to or in connection with the business of a certification authority without including— (a) the licence number; (b) the business name under which it carries on business and the address at which such business is carried on; and (c) any other particulars relating to any services offered as the Commission considers necessary. PART IV DUTIES OF LICENSED CERTIFICATION AUTHORITIES AND SUBSCRIBERS CHAPTER 1 General requirements for licensed certification authorities Use of trustworthy systems 27. (1) A licensed certification authority shall only use a trustworthy system— (a) to issue, suspend or revoke a certificate; (b) to publish or give notice of the issuance, suspension or revocation of a certificate; and (c) to create a private key, whether for itself or for a subscriber. (2) A subscriber shall only use a trustworthy system to create a private key.