Interception of Communications 512 [No. 25 that person may select which of the keys, to disclose for the purposes of complying with the disclosure order. (5) Where a disclosure order is addressed to a person who: (a) was in possession of a key to protected information or traffic data but is no longer in possession of it; and (b) if he had continued to have the key to the protected information or traffic data in his possession, would be required by virtue of the order to disclose it; and (c) is in possession of information that would facilitate the obtaining of discovery of the key to the protected information or traffic data or the putting of the protected information or traffic data into an intelligible form; that person shall disclose to the person to whom he would have been required to disclose the key, all such information as is mentioned in paragraph (c) for the purpose therein mentioned. (6) An authorised officer who obtains a disclosure order shall ensure that such arrangements are made as are necessary for ensuring that: (a) a key disclosed pursuant to the disclosure order is used to obtain access to or put into intelligible form only the protected information or traffic data in relation to which the order was given; (5) every key disclosed pursuant to the disclosure order is stored, for so long as it is retained,