Content transmission system, communication device, and content transmission method

A communication device comprising:

• a fifth communication portion that is capable of communicating with a content transmission device and a content reception device using a second communication method, wherein the content transmission device includes
• an encryption portion that encrypts content data using key information,
• a first communication portion that transmits, using a first communication method, content data encrypted by the encryption portion, and
• a second communication portion that performs communication using the second communication method that differs from the first communication method, and
• the content reception device includes
• a third communication portion that receives encrypted content data transmitted from the first communication portion using the first communication method,
• a decoding portion that decodes encrypted content data received by the third communication portion using key information that is symmetric or asymmetric to the key information, and
• a fourth communication portion that performs communication using the second communication method;
• and
• a key generation portion that generates the key information;
• wherein
• the fifth communication portion transmits the key information generated by the key generation portion to the second communication portion and the fourth communication portion.

A content transmission method comprising the steps of:

• transmitting, by a content transmission device that is compliant with a first transmission method and a second transmission method that differs from the first transmission method, encrypted content data using the first transmission method, the content data being encrypted by the content transmission device using key information;
• receiving and decoding, by a content reception device that is compliant with the first communication method and the second communication method, encrypted content data, the content data being decoded using key information that is symmetric or asymmetric to the key information;
• wherein
• before the step of transmitting,
• a communication device acquires the key information and transmits the acquired key information, using the second communication method, to at least one of the content transmission device and the content reception device.