Content transmission/reception system

Abstract

To provide a device that easily judges that content that has been edited and moved back differs from original content. A content transmission devicedivides edited content composed of partial original content and partial edited content to generate transfer data pieces, generates a nonce value of each piece, encrypts the piece based on the nonce value, and transmits the encrypted transfer data pieces and nonce values. When switch occurs between the partial contents, the devicegenerates nonce value such that discontinuity exists between the generated nonce value and immediately previously generated nonce value. A content reception devicereceives the encrypted transfer data pieces and nonce values, decrypts the pieces based on the nonce values, writes the transfer data pieces into recording medium. When discontinuity exists between currently received nonce value and immediately previously received nonce value, the devicedetects reception of partial edited content.