Patent ID: 7346774

Claim:
A system comprising: means for obtaining an access control entry corresponding to a file to be accessed by the system, wherein the access control entry includes a symmetric key encrypted with a public key of a public/private key pair; means for maintaining a plurality of mappings each of which maps an access control entry to a symmetric key; means for comparing, communicatively coupled to the control module, for checking whether one of the plurality of mappings corresponds to the received access control entry; and a cryptographic means, communicatively coupled to the control module, for: using, if one of the plurality of mappings corresponds to the received access control entry, the symmetric key to which the received access control entry maps to decrypt the file, and using, if one of the plurality of mappings does not correspond to the received access control entry, the private key of the public/private key pair to decrypt the symmetric key, and then use the decrypted symmetric key to decrypt the file.