Patent ID: 7693278
Filing Date: 2010-04-06
Classification: H04L

Abstract:
1. A data distribution apparatus comprising: a packet generating unit including a processor for packetizing data into a plurality of packets, and for adding identification information to a header of each of the plurality of packets, the identification information identifying each of the plurality of packets; an encryption key sharing unit for sharing an encryption key with a data receiver; a packet encrypting unit for dividing data included in each of the plurality of packets generated by said packet generating unit into blocks, and for encrypting the data included in each of the plurality of packets on a block-by-block basis using the encryption key which said encryption key sharing unit shares with said data receiver in such a manner that, when encrypting a first block of the data, said packet encrypting unit encrypts it using the identification information for identifying each of the packets, which is contained, as an initial vector, in the header of each of the plurality of packets, and, when encrypting each subsequent block of the data, encrypts it according to an encryption method which uses an immediately-previously-encrypted block, wherein said packet encrypting unit uses, as said initial vector, an extended sequence number which is a combination of a counter's value indicating the number of times which the sequence number contained in header of each of the plurality of packets exceeds an upper limit of the sequence number and is then cycled, and said sequence number; and a packet communications unit for distributing each of the plurality of packets encrypted by said packet encrypting unit to said data receiver via a communications path.