Importance

Loading Importance Indicators...

Abstract

The present invention relates to a key recovery process used for strong encryption of a message sent by an entity, which message is either to be stored locally or transmitted to another entity, the reading of a message requiring a decryption key which can be reconstructed at least by a trusted third party for key recovery, while added to the message are a compensation field and a compulsory control field which itself comprises at least one key recovery field for allowing at least one trusted third party to supply the decryption keys that enable the encrypted message to be read. This key recovery process is remarkable in that the compulsory control field also comprises, in unencrypted form, the current date as well as the agreement number of the encryption hardware/software and, encrypted under a daily intermediate key, the dialogue key. This key recovery field also comprises, first of all, the identifier of the appropriate trusted third party for key recovery, as a function of the application type, followed by a dialogue key encrypted under the public key or said trusted third party, and lastly, encrypted under the public key of said trusted third party, the serial number of the approved hardware/software and optionally the identifier of the entity and its manager, a working key being used to calculate the daily intermediate key and the period of validity of said working key. Finally, and equally remarkably, during the period of validity of the working key, said working key makes it possible, with only the compulsory control field having been supplied, to calculate in advance for the time period for which the eavesdropping has been authorized, by means of a prescribed formula, daily intermediate keys used to decrypt the dialogue keys, which are themselves used to calculate, from the compensation field and the compulsory control field, the random keys for decrypting the messages.

Loading the Abstract Image...

First Claim