IE20070421U1 - A method for restricting access to digital content - Google Patents

Abstract

ABSTRACT This invention relates to a method for restricting access to digital content. In particular, this invention relates to a method for restricting access to content such as ring tones and the like for mobile communication devices (MCDs). Content is encrypted using a first encryption key prior to being transmitted from a content host (3) to the MCD (5). On arrival, the encrypted content is decrypted using an appropriate key corresponding to the first encryption key. As the content is being decrypted, the decrypted content is re-encrypted using another encryption key specific to the MCD. The MCD (5) is able to access the content on their device using a key corresponding to the encryption key specific to the MCD (5) however the content cannot be sent to another MCD in a decrypted format. In this way, content cannot be passed from one MCD to another and used on the second MCD.

Claims (1)

1. Claims A method for restricting access to content in a mobile communications system (1) comprising a content host (3), a plurality of mobile communications devices (5) equipped with encryption means and a communications network (6) connected therebetween, the steps of the method comprising:- the content host (3) generating a host public-private key pair, the content host transmitting the host private key to the mobile communications devices (5); the encryption means on each mobile communications device (5) providing a user public-private key pair for that device; the content host (3) encrypting content using the host public key; the encrypted content being transmitted from the content host (3) to a mobile communications device (5) via the communications network (6); the mobile communications device decrypting the encrypted content using the host private key and thereafter, re-encrypting the content with the user public key; storing the re-encrypted content on the mobile communications device (5) until access to the content is requested; and on a request to access the re-encrypted content on the mobile communications device, temporarily decrypting the re-encrypted content using the user private key and allowing use of the content on only that mobile communication device. A method as claimed in claim 1 in which the system further comprises a distribution server (7) having memory, and the method further comprises the iritermeciiate steps of: the content host (3) transmitting the encrypted content to the distribution sewer; the distribution server (7) storing the encrypted content in distribution server memory, and thereafter the distribution server transmitting encrypted content onwards to the mobile communications device. A method for restricting access to content on a mobile communications device (5), the method comprising the steps of:- the mobile communication device (5) receiving content in a first encrypted format from a remote content host (3); the mobile communications device (5) decrypting the content using a private encryption key of a content host encryption key pair; re-encrypting the content into a second encrypted format using a public encryption key of a mobile communications device encryption key pair, the mobile communications device encryption key pair being generated using a unique identifier specific to that mobile communications device; and storing an undisclosed private encryption key of the mobile communications device encryption key pair on the mobile communications device, the private encryption key being usable for decrypting the content when required by a mobile communications device user. A method as claimed in claim 3 in which the content is re-encrypted into the second encrypted format immediately after it has been decrypted from the first encrypted format, the decryption and re—encryption forming an atomic operation. A method substantially as hereinbefore described with reference to and as illustrated by the accompanying drawings.