摘要:
A method and system are provided for preventing the unauthorized playback of broadcasted digital data streams. The method includes the step of embedding a watermark in a digital data stream. The digital data stream having the embedded watermark is encrypted. The encrypted digital data stream is broadcasted with a ticket. The encrypted digital data stream and the ticket are received. The ticket is saved and the encrypted digital data stream is provided to a decryption device to decrypt the digital data stream. The decrypted digital data stream is received from the decryption device. The watermark is extracted from the decrypted digital data stream. A one-way cryptographic hashing function is applied to the saved ticket. The hashed ticket-is compared to the extracted watermark. Playback of the digital data stream is prevented, when the hashed ticket does not match the extracted watermark.
摘要:
A security system assesses the response time to requests for information to determine whether the responding system is in physical proximity to the requesting system. Generally, physical proximity corresponds to temporal proximity. If the response time indicates a substantial or abnormal lag between request and response, the system assumes that the lag is caused by the request and response having to travel a substantial or abnormal physical distance, or caused by the request being processed to generate a response, rather than being answered by an existing response in the physical possession of a user. If a substantial or abnormal lag is detected, the system is configured to limit subsequent access to protected material by the current user, and/or to notify security personnel of the abnormal response lag.
摘要:
A system and method includes timing parameters within a node-verification protocol, such as OCPS, to facilitate a determination of the proximity of a target node to a source node. The node-verification protocol includes a query-response sequence, between the source node and the target node. The source node establishes a lower bound on the distance between the source node and the target node based on a measure of the time required to effect this query-response sequence including the time required to communicate the query and response, as well as the time required to process the query and generate the response. The target node includes a measure of the time required to process the query and generate the response to the source node. The source node subtracts this time from the total query-response time to determine the time consumed for the communication.
摘要:
A security system is configured to use a variable length encoding of a security identifier for segments of protected content material. In this system, a distinction is made between a “zero” information bit, and the “absence” of the information bit in a shorter information item. A conventional N-bit information encoding is encoded as a variable bit encoding, wherein the information encoding ranges from N−k bits to N+k bits. By distinguishing “zero” bits from “absent” bits, this variable bit encoding allows for 2N−k+2N−(k−1) . . . +2N . . . +2N+(k−1)+2N+k possible unique information values. Preferably, the number of bits used for each encoding of a segment of a data set is a random value, further adding to the complexity of creating a dictionary mapping for protected content material.
摘要:
A system and method determines the proximity of the target node to the source node from the time required to communicate messages within the node-verification protocol. The node-verification protocol includes a query-response sequence, wherein the source node communicates a query to the target node, and the target node communicates a corresponding response to the source node. The target node is configured to communicate two responses to the query: a first response that is transmitted immediately upon receipt of the query, and a second response based on the contents of the query. The communication time is determined based on the time duration between the transmission of the query and receipt of the first response at the source node and the second response is compared for correspondence to the query, to verify the authenticity of the target node.
摘要:
A check-in/check-out system (100) and method creates limited-duration copies of protected content material (101). The system is configured to allow up-to-N contemporaneous copies (102) of the protected content material. A log (110) maintains a record of the copies currently outstanding, and their expiration times, after which time a conforming rendering device will cease to render the material of this expired copy. When a copy is returned, the entry in the log is deleted (270). If a copy is not returned to the system (100) before its expiration time, the system is configure to also delete its entry from the log (201), thereby allowing another copy to be made (250) to replace the expired copy, even though the expired copy has not been returned.
摘要:
A solar radiation concentrating system (1) comprises at least two reflectors (12, 16) successively arranged along an optical path (4) of the system (1) so that a first (12) of the two reflectors (12, 16) reflects the radiation towards a second (16) of the two reflectors (12, 16). The reflectors (12, 16) have such spectral characteristics as to be capable of highly reflecting the radiation in a reflection range of wavelengths and absorbing the radiation in an absorption range of wavelengths, wherein the absorption range of wavelengths of the first reflector (12) substantially includes the absorption range of wavelengths of the second reflector (16).
摘要:
Radiation filter and reflector device and method which filters certain bandwidths and reflects the transmitted bandwidths of incident radiation, in particular solar radiation. In a preferred embodiment of the device, it filters ultraviolet light below 320 nanometers and reflects all other wavelengths of sunlight. The preferred embodiment of the method comprises the steps of filtering ultraviolet light below 320 nanometers and reflecting all other wavelengths of sunlight. Both device and method provide the user with an effective sunscreen for preventing sunburn while affording tanning.
摘要:
The invention relates to a method of determining a proximity between a root node (301) and a leaf node (303) in a network. The method comprises computing a link proximity value between any two mutually connected nodes in the network, at an initial node, sending a proximity computation request message containing a proximity counter to an intermediate node to which said initial node is connected, at an intermediate node (302) being connected to a first node and to a second node, upon receipt of the proximity computation request message containing a proximity counter from the first node, adding the computed link proximity value to the proximity counter and passing on the proximity computation request message to the second node, at a final node, upon receipt of the proximity computation request message, determining the proximity between the root node and the leaf node as the value indicated by the proximity counter.