Patent ID: 8600056

Claim:
A method of controlling the locking/unlocking of the network access functions of a multifunction terminal including a security processor, executing a public-key cryptography system, wherein said method includes at least: a) allotting said terminal an original public key serving to verify the integrity of data loaded into said terminal; b) generating a pair of keys, including a public key and a private key associated with the access network of said terminal; c) generating an original approval certificate for said terminal containing said public keys, including said original public key and said public key associated with the access network of said terminal; d) establishing for initialization a locking certificate for said terminal containing at least said original approval certificate for said terminal, data for initial configuration of this terminal and a sequence of random data, and storing said locking certificate and said public key associated with the access network of said terminal in a secure area of said security processor, said locking certificate and said public key being signed digitally on the basis of a private key compatible with said original public key and, on boot up for use of said terminal by introduction of a code by a user; e) in the absence of an unlocking certificate for at least one function of the terminal or in the presence of an invalid unlocking certificate, verifying at least the integrity of said locking certificate stored in said secure area of said security processor, and the elements contained in this locking certificate; and f) unlocking and authorizing the use of said terminal or of a specific function of said terminal, conditionally upon a successful verification of said locking certificate stored in said secure area of said security processor and upon validity of the code introduced; and keeping said terminal or said specific function locked and not authorizing the use thereof, otherwise.