A method for securely transmitting information to a content server and an authorized user of a communication device, the method comprising: a content owner device obtaining a first content item; the content owner device obtaining a first tag associated with the first content item, wherein the first tag comprises a set of one or more keywords associated with the first content item and a first content item identifier for identifying the first content item; the content owner device obtaining a first content key for said first content item; the content owner device encrypting the first content item using the first content key, thereby producing a first encrypted content item; the content owner device transmitting information to the content server, the information comprising the first encrypted content item and the first tag, and the method being characterized by: the content owner device deriving a first derived key using at least the first tag, comprising the set of one or more keywords associated with the first content item and the first content item identifier, and a key derivation function; the content owner device encrypting the first content key using the first derived key, thereby producing a first encrypted content key; the content owner device transmitting to the content server the first encrypted content key; the content owner device receiving from the communication device of the user the first content item identifier for identifying the first content item; the content owner device, in response to receiving the first content item identifier, determining whether or not the user is authorized to obtain the first content item identified by the first content item identifier; and the content owner device, in response to determining that the user is authorized to obtain the first content item, transmitting to the communication device of the user the first derived key for decrypting the first encrypted content item. a content owner device obtaining a first content item; the content owner device obtaining a first tag associated with the first content item, wherein the first tag comprises a set of one or more keywords associated with the first content item and a first content item identifier for identifying the first content item; the content owner device obtaining a first content key for said first content item; the content owner device encrypting the first content item using the first content key, thereby producing a first encrypted content item; the content owner device transmitting information to the content server, the information comprising the first encrypted content item and the first tag, the content owner device deriving a first derived key using at least the first tag, comprising the set of one or more keywords associated with the first content item and the first content item identifier, and a key derivation function; the content owner device encrypting the first content key using the first derived key, thereby producing a first encrypted content key; the content owner device transmitting to the content server the first encrypted content key; the content owner device receiving from the communication device of the user the first content item identifier for identifying the first content item; the content owner device, in response to receiving the first content item identifier, determining whether or not the user is authorized to obtain the first content item identified by the first content item identifier; and the content owner device, in response to determining that the user is authorized to obtain the first content item, transmitting to the communication device of the user the first derived key for decrypting the first encrypted content item.