Content authentication for digital media based recording devices

A processing system for determining if a file is modified or not, includes a recording device and a certificate authority terminal, said system comprising:

• said recording device comprising:
• a generator for generating a first public key and a first private key;
• and
• a first transmitter for transferring the first public key to the certificate authority terminal;
• said certificate authority terminal comprising:
• an encoder for encoding a certificate including the first public key received from the recording device by using a second private key;
• and
• a second transmitter for transferring the encoded certificate to the recording device;
• said recording device further comprising:
• a provider for hashing said file to provide a digital signature by using the first private key;
• attaching means for attaching the certificate received from the certificate authority terminal and the digital signature to said file;
• and
• a distributor for distributing to a client terminal said file as a communication package assimilated at least said file, the digital signature and the certificate.

Apparatus comprising:

• first storage media for storing at least a digital certificate and a pair of cryptographic keys comprising a private key, and a public key corresponding to said private key;
• a recording arrangement for recording event data;
• second storage media for storing at least said recorded event data;
• a signing processor for generating a digital signature using at least said stored private key and said recorded event data;
• and
• a controller arranged to cause said apparatus to:
• (i) supply said stored public key to a certificate generating authority;
• (ii) store said digital certificate in at least said second storage media, said certificate being formed using said public key and supplied to said apparatus from said certificate generating authority;
• and
• (iii) record event data and to associate a digital signature generated by said signing processor with said event data.

A device for processing data intended for subsequent authentication, said device comprising:

• means for receiving a digital certificate generated from a private key of a certifying authority and incorporating a public key of said device;
• means for generating a digital signature for said data and a private key of said device, said private key of said device complementing said public key of said device to collectively form a device key-pair;
• and
• means for associating said data, said certificate and said digital signature as a communication package for transfer from said device.

A method, in a recording device, of determining if a file is modified or not, said method comprising the steps of:

• generating a first public key and a first private key;
• transferring the first public key to a certificate authority terminal;
• hashing said file to provide a digital signature by using the first private key;
• attaching a certificate received from the certificate authority terminal and the digital signature to said file;
• and
• distributing to a client terminal said file as a communication package assimilated at least said file, the digital signature and the certificate by the recording device,
• wherein the certificate received from the certificate authority includes the first public key and is encoded by using a second private key generated in the certificate authority terminal.

A storage medium storing a program for executing a process of determining if a file is modified or not, said program comprising the step of:

• generating a first public key and a first private key;
• transferring the first public key to a certificate authority terminal;
• hashing said file to provide a digital signature by using the first private key;
• attaching a certificate received from the certificate authority terminal and the digital signature to said file;
• and
• distributing to a client terminal said file as a communication package assimilated at least said file, the digital signature and the certificate by the recording device,
• wherein the certificate received from the certificate authority includes the first public key and is encoded by using a second private key generated in the certificate authority terminal.