An information processing system comprising: • a medium in which content is stored; and • a playing apparatus configured to play the content stored in said medium; wherein said playing apparatus is further configured to: ∘ selectively activate a playing program of the playing apparatus according to a content type of selected content selected among the content stored in said medium, wherein the content type is a first content type corresponding to high value-added content, a second content type corresponding to normal content other than the high value-added content, or a third content type corresponding to the high value-added content and the normal content, ∘ obtain a device certificate correlated with the playing program from a storage unit of the playing apparatus by execution of the selectively activated playing program, and ∘ transmit the obtained device certificate to said medium; and wherein in the device certificate content type information is recorded, wherein the content type information indicates the first content type, the second content type or the third content type; • wherein said medium is configured to: ∘ determine whether or not an encryption key of which a reading request has been performed from said playing apparatus is an encryption key for decrypting an encrypted content, wherein the encryption key of which the reading request has been performed corresponds to the content type of the selected content, and the determining whether or not the encryption key of which the reading request has been performed from the playing apparatus is the encryption key for decrypting the encrypted content is performed by comparing a content type contained in the device certificate with the content type to which the encryption key corresponds to and ∘ permit readout of the encryption key only in the case that a content type contained in the device certificate matches the content type to which the encryption key corresponds to. • a medium in which content is stored; and • a playing apparatus configured to play the content stored in said medium; wherein said playing apparatus is further configured to: ∘ selectively activate a playing program of the playing apparatus according to a content type of selected content selected among the content stored in said medium, wherein the content type is a first content type corresponding to high value-added content, a second content type corresponding to normal content other than the high value-added content, or a third content type corresponding to the high value-added content and the normal content, ∘ obtain a device certificate correlated with the playing program from a storage unit of the playing apparatus by execution of the selectively activated playing program, and ∘ transmit the obtained device certificate to said medium; and wherein in the device certificate content type information is recorded, wherein the content type information indicates the first content type, the second content type or the third content type; ∘ selectively activate a playing program of the playing apparatus according to a content type of selected content selected among the content stored in said medium, wherein the content type is a first content type corresponding to high value-added content, a second content type corresponding to normal content other than the high value-added content, or a third content type corresponding to the high value-added content and the normal content, ∘ obtain a device certificate correlated with the playing program from a storage unit of the playing apparatus by execution of the selectively activated playing program, and ∘ transmit the obtained device certificate to said medium; and wherein in the device certificate content type information is recorded, wherein the content type information indicates the first content type, the second content type or the third content type; • wherein said medium is configured to: ∘ determine whether or not an encryption key of which a reading request has been performed from said playing apparatus is an encryption key for decrypting an encrypted content, wherein the encryption key of which the reading request has been performed corresponds to the content type of the selected content, and the determining whether or not the encryption key of which the reading request has been performed from the playing apparatus is the encryption key for decrypting the encrypted content is performed by comparing a content type contained in the device certificate with the content type to which the encryption key corresponds to and ∘ permit readout of the encryption key only in the case that a content type contained in the device certificate matches the content type to which the encryption key corresponds to. ∘ determine whether or not an encryption key of which a reading request has been performed from said playing apparatus is an encryption key for decrypting an encrypted content, wherein the encryption key of which the reading request has been performed corresponds to the content type of the selected content, and the determining whether or not the encryption key of which the reading request has been performed from the playing apparatus is the encryption key for decrypting the encrypted content is performed by comparing a content type contained in the device certificate with the content type to which the encryption key corresponds to and ∘ permit readout of the encryption key only in the case that a content type contained in the device certificate matches the content type to which the encryption key corresponds to.