Patent ID: 7321660

Claim:
A security method, comprising: first operations, effected by a discloser of data, comprising encrypting the data and providing the encrypted data to a recipient, the encryption process using both an encryption key comprising a future time value, and public data provided by a trusted party, the public data being derived thereby from private data; and second operations effected by the trusted party where the trusted party is arranged to perform at specific time intervals in response to signals from a clock, the second operations comprising: using both said private data and further data in order to determine, at the specific time intervals, a decryption key which is then output and outputting the decryption key by publishing it via a distribution system; said further data comprising, at each determination of the decryption key, a current time value derived independently of said encryption key, the decryption key being so determined that, for said current time value equalling the future time value used by the data discloser for its encryption key, the decryption key is useful to decrypt the discloser's encrypted data.