Patent ID: 8756415

Claim:
A memory system comprising: a host device; and a memory device configured to communicate with said host device; said host device including a storage device configured to store at least certificate information issued by a certificate authority, public key information of said certificate authority for verifying a certificate, and revocation information identifying at least one revoked memory device and at least one revoked external device, and a first control section configured to control access to said storage device and to have a function of communicating with an external memory device including a secret area for storing data of which the confidentiality upon connection is to be guaranteed, said first control section has a function of exchanging said revocation information through communication between said host device and said external memory device in such a manner that a new version of said revocation information is transferred from one of the two devices in possession thereof to the other device possessing an old version of said revocation information for revocation information synchronization between said two devices, and upon completion of a process of revocation information synchronization between said two devices, said first control section is allowed to access said secret area, said memory device including a storage section configured to store public key information of a certificate authority for verifying a certificate and revocation information identifying at least one revoked memory device and at least one revoked external device, and to include a secret area for storing data of which the confidentiality is to be guaranteed, and a second control section configured to have a function of communicating with an external device and to control access to said secret area of said storage section at least in accordance with said revocation information, said second control section has a function of exchanging said revocation information through communication between said memory device and said external device in such a manner that a new version of said revocation information is transferred from one of the two devices in possession thereof to the other device possessing an old version of said revocation information for revocation information synchronization between said two devices, and said second control section inhibits access to said secret area unless a process of revocation information synchronization is completed between said two devices.