Disclosed is a method for locking and unlocking a mobile telephone. The method comprises setting a locking mode by receiving a locking voice, a locking-wait time and a locking number; receiving a locking voice when there is a key input in the locking mode; partially releasing the locking function when the received locking voice is identical to a registered locking voice; switching an operation mode of the mobile telephone to an idle mode, after partially releasing the locking function; and switching the operation mode of the mobile telephone back to the locking mode, when there is no key input in the idle mode until the locking-wait time has elapsed.

A cellular phone subsidy lock which ensures that a cellular phone, sold to an end-user at a price subsidized by a cellular carrier, is activated only on the subsidizing carrier's network, and not on a competitor's network. A secure carrier code, specific to and known by the subsidizing carrier, is programed into the cellular phone by the phone manufacturer. The phone is programmed and shipped by the manufacturer in a locked condition, which prevents programming of the NAM (Number Assignment Module) of the cellular phone without first entering either a valid unlock code or a valid remove lock code. At the time of phone activation and programming of the NAM, the phone's ESN (Electronic Serial Number) is entered into the carrier computer system, which utilizes the ESN and carrier code to execute a subsidy lock algorithm which outputs an unlock code and a remove lock code. At the carrier's choice, either code is given to the end user to be entered into the phone. The phone then executes the same subsidy lock algorithm, using the carrier code programmed at the time of manufacture, and it's own ESN, to calculate the unlock code and the remove lock code. If the code entered by the user matches the unlock code, NAM programming is allowed to proceed only once, and if the entered number matches the remove lock code, the phone removes the subsidy lock completely.

Improved key management is provided by a public key replacement apparatus and method for operating over insecure networks. An active public key and the mask of a replacement public key are provided by a key server to nodes where the active key is used to encrypt and verify messages. To replace the active public key with the replacement public key, a key replacement message is sent to the node. The key replacement message contains the replacement public key and contains the mask of the next replacement key. The mask of the replacement public key may be generated by hashing or encrypting. The key replacement message is signed by the active public key and the replacement public key. Nodes are implemented by a computer, a smart card, a stored data card in combination with a publicly accessible node machine, or other apparatus for sending and/or receiving messages. In a particular application, a financial transaction network, nodes are consumer nodes, merchant nodes, or both, and transactions are securely sent over a possible insecure network.

Apparatus and methods are provided for controlling a video system. In one embodiment the apparatus includes a remote controller including a device for scanning a printed input data card including a type code printed on the input data card, the type code for representing a category of input data printed on the card, and the type code printed as a line of patterns, each pattern being relatively dark or light to represent a binary one or binary zero, and the input data card including a plurality of printed input data, each input data printed as a line of patterns, each pattern being relatively dark or light to represent a binary one or binary zero. The apparatus further includes a television for storing the received input data and the type code and for enabling viewing of only programs in the stored input data, each program having a channel, a date, a time-of-day, and a length of time.

An apparatus and method for parental control of television programs. Program schedule information including program titles are stored in a memory and displayed on a monitor. Compressed code is entered for the programs to be blocked. Alternatively, one or more program titles are selected from the displayed program schedule information for blocking by a parental control circuitry connected to a controller.