摘要:
In a system composed of a recording apparatus that records digitized content such as a movie, or a reproduction apparatus that reproduces the digitized content, and a recording medium, a media key for use in recording or reproduction is encrypted by a plurality of device keys and recorded on the recording medium. Here, the recording apparatus or the reproduction apparatus specifies the encrypted media key that it is to decrypt, from amongst the plurality of encrypted media keys. A key management apparatus records node revocation patterns assigned to nodes in a tree structure to the recording medium in a particular order, as header information of key information, together with the encrypted media keys. The recording apparatus or the reproduction apparatus specifies the encrypted media key to be decrypted, by analyzing the node revocation patterns sequentially.
摘要:
A method for use in a distribution system having a key management center, a distribution station and a reception terminal. The method updates a pair of distribution keys unique to the reception terminal, where the distribution public key is used to encrypt distribution data, and the distribution secret key is used to decrypt encrypted data. In the key updating method, the reception terminal acquires an update secret key prior to data distribution, and the key management center acquires an update public key making a pair with the update secret key, generates a new pair of distribution keys, encrypts a new distribution secret key by using the update public key, transmits an encrypted secret key to the reception terminal and updates to the new distribution public key. The reception terminal receives the encrypted secret key and restores the new distribution secret key by decrypting it using the update secret key and updates to the new distribution secret key.
摘要:
A parameter generation apparatus for generating parameters causing no decryption error for an NTRU cryptosystem so that an encrypted communication can be carried out between an encryption apparatus and a decryption apparatus in a secure and reliable manner, is comprised of: a provisional parameter generation unit operable to generate a set of provisional parameters that do not cause any decryption errors, based on error condition information that is provided in advance, said error condition information indicating a condition for causing no decryption error; and an output parameter generation unit operable to generate an output parameter that does not cause any decryption errors, using said set of provisional parameters, based on a lattice constant that is calculated from said set of provisional parameters.
摘要:
In a mutual authentication method for use between a recording apparatus which records copied contents on a recording medium having an arithmetic processing function, and the recording medium, the method includes a step of storing in the recording medium at least first information which depends on the recording medium, and second information which is to be shared by the recording apparatus in executing mutual authentication with the recording apparatus and depends on the recording medium, and a step of generating by the recording apparatus authentication information used in mutual authentication with the recording medium on the basis of the first information obtained from the recording medium, and executing mutual authentication between the recording apparatus and the recording medium using the generated authentication information and the second information.
摘要:
A cryptographic apparatus reads, from a portable storage medium, content data and cryptographic information specifying a certain part of the content data on which cryptographic processing is to be performed, specifies the certain part in the read content data based on the read cryptographic information, and performs one of encryption and decryption on the certain part. When, for example, the content data is formed from alternating headers and variable-length data sections, the cryptographic information is a program formed from an instruction sequence. The instruction sequence has the cryptographic apparatus detect a header in the content data, read the length of the variable-length data, and perform cryptographic processing on a part of the content data between a start point and an end point, the start point being a position relative to the header position, and the end point being a value resulting from adding the length to the start point.
摘要:
To provide a broadcasting system in which a content user can select CMs that he or she wants. A sub-content index-information presenting unit presents sub-content index information. A user selects in advance sub-contents that he or she wants to view, by referring to the sub-content index information, and views only the selected sub-contents.
摘要:
The present invention provides an encryption system, by which it is possible to safely distribute a common crypt key for decrypting data on an encrypted DVD-ROM by simple devices and procedure. A terminal equipment 1 comprises a DVD-ROM drive, means for sending a key data request to a center device via communication line, and means for decrypting the encrypted common crypt key using a combination of a part of BCA data and a membership number. A center device 2 comprises means for authenticate a user by searching a user data base 23 in response to the key data request, means for obtaining BCA data of the user by searching a BCA data base 21, means for obtaining a common crypt key by searching a key data base 22, and means for encrypting and transmitting the common crypt key using a combination of a part of BCA data and a membership number. Because a combination of a part of BCA data already distributed and the membership number is used as a key for encrypting the common crypt key, it is possible to safely encrypt and transmit the common crypt key by simple devices and procedure.
摘要:
A message receiving apparatus for receiving messages from a message transmitting apparatus generates first data for producing a display which urges a user of the message transmitting apparatus to input a message, and generates second data within the first data for specifying a conversion type for secret communication of the message. The message receiving apparatus sends the first data including the second data to the message transmitting apparatus and subsequently receives the message from the message transmitting apparatus. The message transmitting apparatus for transmitting messages to the message receiving apparatus receives the first data for producing the display and the accompanying second data for specifying the conversion type and produces the display according to the first data. On receiving the message inputted by the user in response to the display, the message transmitting apparatus converts the input message according to the second data and transmits the converted message to the message receiving apparatus.
摘要:
In an encrypted transmission system composed of one transmission apparatus 10 and twenty-eight reception apparatuses A1-G4 that are classified into seven groups A-G, two secret key exclusively selected out of a total of fourteen secret keys are distributed beforehand to each group. The transmission apparatus 10 encrypts the same message M using one of the two secret keys distributed to each group and sends each group a message M encrypted with one of the group's secret keys. The reception apparatuses each decrypt the received cryptogram separately using each of the secret keys assigned to the of group to which each reception apparatus belongs, judge whether either of the two decryption results conforms to a predetermined rule, and specify the correct decryption result.
摘要:
A 6-digit decimal input value A and a previously prepared 6-digit decimal extension fixed value L are substituted in an extension function f, thereby extending the input value A to a 12-digit decimal value f(A,L). This extended value f(A,L) is bit-agitated with a bit agitation key R. Further, a value C obtained by the bit agitation processing is substituted in a reduction function g, thereby obtaining a 6-digit decimal output value B. Thus, the input value A is extended by the extension processing to be thereafter subjected to the bit agitation processing, whereby safety of secret information can be improved without increasing the number of digits of the input value A. Further, the value obtained by the bit agitation is thereafter reduced, whereby the output value B can be reduced to a number of digits which is applicable to the human memory. Thus, a bit agitator is obtained which is safer than at conventional one and has an excellent user interface.