Transmitter, receiver, and transmitting method

Abstract

According to one embodiment, a transmitting method transmits a start request for an authentication and key exchange from at least one of receivers to the transmitter, performs an authentication and key exchange for at least one of a first key common to the receivers and a second key peculiar to the at least one of the receivers, and encrypts the content by using a key shared by the transmitter and the at least one of the receivers to transmit the encrypted content to the at least one of the receivers.

1 . A transmitting method for transmitting a content from a transmitter to at least one of receivers, the method comprising: 
 transmitting a start request for an authentication and key exchange from the at least one of receivers to the transmitter;    performing an authentication and key exchange for at least one of a first key common to the receivers and a second key peculiar to the at least one of the receivers; and    encrypting the content by using a key shared by the transmitter and the at least one of the receivers to transmit the encrypted content to the at least one of the receivers.    
   
   
       2 . The transmitting method according to  claim 1 , wherein the transmitting comprises: 
 transmitting a content retrieval request from the at least one of the receivers to the transmitter;    transmitting a retrieval result from the transmitter to the at least one of the receivers in response to the content retrieval request; and    transmitting the start request from the at least one of the receivers to the transmitter in response to the retrieval result, and    the encrypting comprises:    transmitting a content request from the at least one of the receivers to the transmitter; and    transmitting an encrypted content from the transmitter to the at least one of the receivers in response to the content request.    
   
   
       3 . The transmitting method according to  claim 1 , wherein the performing transmits the second key and identification information of the second key from the transmitter to the at least one of the receivers; and 
 the encrypting comprises:    transmitting a content request including identification information of the second key from the at least one of the receivers to the transmitter; and    transmitting an encrypted content encrypted with the second key specified by the identification information included in the content request from the transmitter to the at least one of the receivers.    
   
   
       4 . The transmitting method according to  claim 3 , further comprising: 
 determining whether the at least one of the receivers possesses the second key specified by the identification information before receiving the encrypted content, and stopping receiving the encrypted content if it is determined that the at least one of the receivers does not possess the second key; and    disabling the content encrypted with the second key after completing a transmission of the encrypted content.    
   
   
       5 . The transmitting method according to  claim 1 , wherein the transmitting comprises: 
 transmitting a content receiving request from the transmitter to the at least one of the receivers; and    transmitting the start request from the at least one of the receivers to the transmitter, and the performing comprises:    transmitting a completion notification of an authentication and key exchange from the transmitter to the at least one of the receivers after completing the authentication and key exchange; and    transmitting a content reception acknowledgement from the at least one of the receiver to the transmitter.    
   
   
       6 . The transmitting method according to  claim 5 , wherein the performing comprising transmitting the second key and identification information of the second key from the transmitter to the at least one of the receivers; and 
 the encrypting comprises transmitting the identification information of the second key and an encrypted content encrypted with the second key specified by the identification information from the transmitter to the at least one of the receivers.    
   
   
       7 . The transmitting method according to  claim 6 , further comprising: 
 determining whether the at least one of the receivers possesses the second key specified by the identification information before receiving the encrypted content, and stopping receiving the encrypted content if it is determined that the at least one of the receivers does not possess the second key; and    disabling the content encrypted with the second key after completing a transmission of the encrypted content.    
   
   
       8 . The transmitting method according to  claim 1 , wherein the first key comprises a key for rendering the content, and the second key comprises a key for moving the content.  
   
   
       9 . The transmitting method according to  claim 1 , wherein the transmitting, performing, and encrypting are executed by different connections, respectively.  
   
   
       10 . A transmitting method for transmitting a content from a transmitter to a receiver, comprising: 
 transmitting a content receiving request from the transmitter to the receiver;    transmitting a start request for an authentication and key exchange from the receiver to the transmitter;    notifying completion of the authentication and key exchange from the transmitter to the receiver; and    transmitting a content reception acknowledgement notification from the receiver to the transmitter.    
   
   
       11 . The transmitting method according to  claim 10 , wherein the content reception acknowledgement notification transmitting comprises transmitting a key peculiar to the receiver and identification information of the key from the transmitter to the receiver; and 
 the content reception acknowledgement notification transmitting comprises transmitting the content reception acknowledgement notification including the identification information of the key from the receiver to the transmitter.    
   
   
       12 . The transmitting method according to  claim 10 , wherein the start request for an authentication and key exchange transmitting comprises: 
 performing an authentication and key exchange for a first key common to a plurality of receivers;    transmitting the first key from the transmitter to at least one of the receivers;    requesting a second key from the at least one of the receivers to the transmitter; and    transmitting the second key from the transmitter to the at least one of the receivers.    
   
   
       13 . The transmitting method according to  claim 10 , wherein the start request for an authentication and key exchange transmitting comprises: 
 performing an authentication and key exchange for the first key and the second key; and    transmitting the first key and the second key from the transmitter to the at least one of the receivers.    
   
   
       14 . A transmitter which transmits a content to a receiver, comprising: 
 a first unit configured to perform an authentication and key exchange for a first key common to a plurality of receivers; and    a second unit configured to perform an authentication and key exchange for second keys for the receivers.    
   
   
       15 . The transmitter according to  claim 14 , further comprising: 
 a third unit configured to transmit a retrieval result to the at least one of the receivers in response to a content retrieval request transmitter from the at least one of the receivers;    a fourth unit configured to perform an authentication and key exchange by one of the first unit and the second unit in response to an authentication and key exchange start request transmitted from the at least one of the receivers to transmit a second key peculiar to the at least one of the receivers and identification information of the second key to the at least one of the receivers; and    a fifth unit configured to transmit an encrypted content with the second key specified by the identification information to the at least one of the receivers in response to a content request including the identification information of the second key and transmitted from the at least one of the receivers.    
   
   
       16 . The transmitter according to  claim 14 , further comprising: 
 a third unit configured to transmit a content receiving request to the at least one of the receivers; and    a fourth unit configured to transmit an encrypted content encrypted with the Second key and the identification information of the second key in response to a content reception acknowledgement transmitted from the at least one of the receivers.    
   
   
       17 . A receiver which receives a content transmitted from a transmitter, comprising: 
 a first unit configured to perform an authentication and key exchange for a first key common to a plurality of receivers; and    a second unit configured to perform an authentication and key exchange for a second key peculiar to the receiver.    
   
   
       18 . The receiver according to  claim 17 , further comprising: 
 a third unit configured to transmit a content retrieval request to a transmitter;    a fourth unit configured to transmit an authentication and key exchange start request for the second key to the transmitter;    a fifth unit configured to transmit a content request including identification information of the second key to the transmitter when receiving an authentication and key exchange completion notification transmitted from the transmitter; and    a sixth unit configured to receive an encrypted content encrypted with the second key and identification information of the second key from the transmitter.    
   
   
       19 . The receiver according to  claim 17 , further comprising: 
 a third unit configured to transmit an authentication and key exchange start request for the second key to the transmitter when receiving a content receiving request from the transmitter;    a fourth unit configured to transmit a content reception acknowledgement including identification information of the second key; and    a fifth unit configured to receive encrypted content encrypted with the second key and the identification information of the second key from the transmitter.