초록 ▼

To render digital content encrypted according to a content key (KD) on a first device having a public key (PU1) and a corresponding private key (PR1), a digital license corresponding to the content is obtained, where the digital license includes the content key (KD) therein in an encrypted form. The

To render digital content encrypted according to a content key (KD) on a first device having a public key (PU1) and a corresponding private key (PR1), a digital license corresponding to the content is obtained, where the digital license includes the content key (KD) therein in an encrypted form. The encrypted content key (KD) from the digital license is decrypted to produce the content key (KD), and the public key (PU1) of the first device is obtained therefrom. The content key (KD) is then encrypted according to the public key (PU1) of the first device (PU1 (KD)), and a sub-license corresponding to and based on the obtained license is composed, where the sub-license includes (PU1 (KD)). The composed sub-license is then transferred to the first device.

대표청구항 ▼

The invention claimed is: 1. A method of checking out a sub-license to a first device from a second device and checking in the checked-out sub-license, comprising: the first device receiving a request from the second device for a nonce, and the first device providing such nonce; the first device re

The invention claimed is: 1. A method of checking out a sub-license to a first device from a second device and checking in the checked-out sub-license, comprising: the first device receiving a request from the second device for a nonce, and the first device providing such nonce; the first device receiving from the second device the checked-out sub-license and the provided nonce; the first device determining whether the nonce received is the same nonce provided to the second device; if the first device determines that the nonce received is the same nonce provided, the first device concluding that the received sub-license is legitimate and storing the sent sub-license; the first device deleting the checked-out sub-license and then providing a trusted indication to the second device that the checked-out sub-license has in fact been deleted; and the second device adding the checked-out sub-license to a catalog by adding an entry including an identifier identifying the checked-out sub-license and an identifier identifying the first device to the catalog, wherein checking in the checked-out sub-license includes: the first device requesting a nonce from the second device, and receiving such nonce; and the first device sending to the second device the received nonce, an identifier identifying the first device, and a list of all sub-licenses currently resident on the first device, wherein the deleted checked-out sub-license is not in the sent list, wherein when the second device concludes that the nonce sent by the first device is the same nonce received by the first device, the second device concludes that the sent identifier and list that accompanied the sent nonce is legitimate, compares the sent list with the catalog and notes that the deleted checked-out sub-license is in the catalog but not on the sent list, and deletes the entry having the identifier identifying the deleted checked-out sub-license and the identifier identifying the first device from the catalog. 2. A method of checking out a sub-license from a second device to a first device and checking in the checked-out sub-license comprising: the second device requesting a nonce from the first device, and receiving such nonce; the second device sending the checked-out sub-license and the received nonce to the first device, wherein when the first device concludes that the nonce sent by the second device is the same nonce received by the second device, the first device concludes that the sent sub-license that accompanies the sent nonce is legitimate, and stores the sent sub-license; the second device adding the checked-out sub-license to a catalog, wherein adding the checked-out sub-license to the catalog comprises the second device adding an entry including an identifier identifying the checked-out sub-license and an identifier identifying the first device to the catalog, and the second device receiving a trusted indication from the first device that the checked-out sub-license has been deleted, wherein checking in the checked-out sub-license includes: the second device receiving a request from the first device for a nonce, and providing such nonce; the second device receiving from the first device the provided nonce, the identifier identifying the first device, and a list of all sub-licenses currently resident on the first device, wherein the deleted checked-out sub-license is not in the sent list; the second device determining whether the received nonce is the same nonce provided to the first device; if the received nonce is the same nonce provided to the first device, the second device concluding that the received identifier and list is legitimate; the second device comparing the received list with the catalog and noting that the deleted checked-out sub-license is in the catalog but not on the sent list; and the second device deleting the entry having the identifier identifying the deleted checked-out sub-license and the identifier identifying the first device from the catalog. 3. A method of checking out a sub-license from a second device to a first device and checking in the checked-out sub-license comprising: requesting, by the second device, a nonce from the first device, and receiving such nonce; sending, by the second device, the checked-out sub-license and the received nonce to the first device; determining, by the first device, whether the nonce sent by the second device is the same nonce provided to the second device by the first device; if the nonce sent by the second device is the same nonce provided to the second device by the first device, concluding, by the first device, that the sent sub-license that accompanies the sent nonce is legitimate and storing, by the first device, the sent sub-license; adding, by the second device, the checked-out sub-license to a catalog, wherein adding the checked-out sub-license to the catalog comprises adding an entry including an identifier identifying the checked-out sub-license and an identifier identifying the first device to the catalog, and deleting the checked-out sub-license from the first device and then the first device providing a trusted indication to the second device that the checked-out sub-license has in fact been deleted, wherein checking in the checked-out sub-license includes: deleting, by the first device, the checked-out sub-license therefrom; requesting, by the first device, a nonce from the second device, and receiving such nonce; sending, by the first device to the second device, the received nonce, the identifier identifying the first device, and a list of all sub-licenses currently resident on the first device, wherein the deleted checked-out sub-license is not in the sent list; determining, by the second device, whether the nonce sent by the first device to the second device is the same nonce received by the first device; if the nonce sent by the first device to the second device is the same nonce received by the first device, therefore concluding, by the second device, that the sent identifier and list that accompanied the sent nonce is legitimate; comparing, by the second device, the sent list with the catalog, and noting whether the deleted checked-out sub-license is in the catalog but not on the sent list; and if the deleted checked-out sub-license is in the catalog but not on the sent list, deleting, by the second device, the entry having the identifier identifying the deleted checked-out sub-license and the identifier identifying the first device from the catalog. 4. A computer-readable storage medium having instructions stored thereon that when executed by a processor of a first device implements a method of checking out a sub-license to the first device from a second device and checking in the checked-out sub-license, the method comprising: the first device receiving a request from the second device for a nonce, and the first device providing such nonce; the first device receiving from the second device the checked-out sub-license and the provided nonce; the first device determining whether the nonce received is the same nonce provided to the second device; and if the first device determines that the nonce received is the same nonce provided, the first device concluding that the received sub-license is legitimate and storing the sent sub-license, wherein, when checking in the checked-out sub-license, the first device deletes the checked-out sub-license and then provides a trusted indication to the second device that the checked-out sub-license has in fact been deleted, wherein the second device adds the checked-out sub-license to a catalog by adding an entry including an identifier identifying the checked-out sub-license and an identifier identifying the first device to the catalog, and wherein checking in the checked-out sub-license further includes: the first device reQuesting a nonce from the second device, and receiving such nonce; and the first device sending to the second device the received nonce, an identifier identifying the first device, and a list of all sub-licenses currently resident on the first device, wherein the deleted checked-out sub-license is not in the sent list, wherein when the second device concludes that the nonce sent by the first device is the same nonce received by the first device, the second device concludes that the sent identifier and list that accompanied the sent nonce is legitimate, compares the sent list with the catalog and notes that the deleted checked-out sub-license is in the catalog but not on the sent list, and deletes the entry having the identifier identifying the deleted checked-out sub-license and the identifier identifying the first device from the catalog. 5. A computer-readable storage medium having instructions stored thereon that when executed by a processor of a second device implements a method of checking out a sub-license to a first device from the second device and checking in the checked-out sub-license, the method comprising: the second device requesting a nonce from the first device and receiving such nonce; the second device providing the checked-out sub-license and the provided nonce; adding the checked-out sub-license to a catalog by adding an entry including an identifier identifying the checked-out sub-license and an identifier identifying the first device to the catalog; and the second device checking in the checked-out sub-license by: providing a nonce to the first device; and receiving from the first device the nonce received by the first device, an identifier identifying the first device, and a list of all sub-licenses currently resident on the first device, wherein the deleted checked-out sub-license is not in the sent list, wherein when checking in the checked-out sub-license, the second device further determines whether the nonce received from the first device is the nonce provided to the first device and, if so, the second device concluding that the sent identifier and list that accompanied the sent nonce is legitimate, comparing the sent list with the catalog and noting that the deleted checked-out sub-license is in the catalog but not on the sent list, and deleting the entry having the identifier identifying the deleted checked-out sub-license and the identifier identifying the first device from the catalog. 6. The medium of claim 5, wherein checking in the checked-out sub-license further comprises the second device receiving a trusted indication from the first device that the checked-out sub-license has been deleted. 7. A system including a first device and a second device, the second device checking out a sub-license to the first device, wherein the first device comprises: means for receiving a request from the second device for a nonce; means for providing such nonce to the second device; means for receiving from the second device the checked-out sub-license and the provided nonce; means for determining whether the nonce received is the same nonce provided to the second device; and means for concluding that the received sub-license is legitimate and storing the sent sub-license if the nonce received is the same nonce provided to the second device, wherein the first device includes means for deleting the checked-out sub-license and for providing a trusted indication to the second device that the checked-out sub-license has in fact been deleted when checking in the checked-out sub-license, wherein the second device includes means for adding the checked-out sub-license to a catalog by adding an entry including an identifier identifying the checked-out sub-license and an identifier identifying the first device to the catalog, wherein the first device further includes means for requesting a nonce from the second device and for receiving such nonce, and means for sending to the second device the received nonce, an identifier identifying the first device, and a list of all sub-licenses currently resident on the first device, wherein the deleted checked-out sub-license is not in the sent list, and wherein the second device includes means for determining whether the nonce sent by the first device is the same nonce received by the first device and, if so, the determining means determining that the sent identifier and list that accompanied the sent nonce is legitimate, the second device further including means for comparing the sent list with the catalog and noting that the deleted checked-out sub-license is in the catalog but not on the sent list, and means for deleting the entry having the identifier identifying the deleted checked-out sub-license and the identifier identifying the first device from the catalog. 8. A system including a first device and a second device, the second device checking out a sub-license to the first device, the second device comprising means for requesting a nonce from the first device and for receiving such nonce, and means for sending the checked-out sub-license and the received nonce to the first device; and the first device comprising means for determining whether the nonce sent by the second device is the same nonce received by the second device and, if so, for concluding that the sent sub-license that accompanies the sent nonce is legitimate and for storing the sent sub-license, wherein the second device includes means for adding the checked-out sub-license to a catalog, wherein the means for adding the checked-out sub-license to the catalog adds an entry including an identifier identifying the checked-out sub-license and an identifier identifying the first device to the catalog, wherein the second device includes means for receiving a trusted indication from the first device that the checked-out sub-license has been deleted when checking in the checked-out sub-license, wherein the second device further comprises receiving means for receiving a request from the first device for a nonce, means for providing such nonce to the first device, wherein the receiving means further receives from the first device the provided nonce, the identifier identifying the first device, and a list of all sub-licenses currently resident on the first device, wherein the deleted checked-out sub-license is not in the sent list, and wherein the second device further includes means for determining whether the received nonce is the same nonce provided to the first device and, if so, concluding that the received identifier and list is legitimate and comparing the received list with the catalog, noting that the deleted checked-out sub-license is in the catalog but not on the sent list, and deleting the entry having the identifier identifying the deleted checked-out sub-license and the identifier identifying the first device from the catalog.