Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
195 words
A method of secured communication in a telecommunications system including at least two communication exchanges and a plurality of user equipments, wherein each user equipment is provided with a store which holds a user variable data word particular to that user; and, each exchange is provided with a store which holds all the user variables data words of the users connected to it, and, each exchange is provided with its own random variable data word, so that when a first user makes a secure call to a second user, the first user equipment encrypts the call using its particular user variable data word and sends the encrypted data to its own exchange, the exchange is provided with equipment for decrypting the call using the particular user variable data word and generates the random variable data word that will be used for the call, and encrypts it with the particular user variable data word and returns it to the first user; the exchange also sends the random variable data word to the second user's exchange which encrypts it with the user variable data word particular to the second user and sends it to the second user.
Claim 2
Independent Claim
195 words
A method of secured communication in a telecommunications system including at least two communication exchanges and a plurality of user equipments, wherein each user equipment is provided with a store which holds a user variable data word particular to that user; and, each exchange is provided with a store which holds all the user variables data words of the users connected to it, and, each exchange is provided with its own random variable data word, so that when a first user makes a secure call to a second user, the first user equipment encrypts the call using its particular user variable data word and sends the encrypted data to its own exchange, the exchange is provided with equipment for decrypting the call using the particular user variable data word and generates the random variable data word that will be used for the call, and encrypts it with the particular user variable data word and returns it to the first user; the exchange also sends the random variable data word to the second user's exchange which encrypts it with the user variable data word particular to the second user and sends it to the second user.
Claim 3
Independent Claim
30 words
A method of secured communication as claimed in claim l, wherein different random variable data words are generated to enable a user in telephony communication to change to data communication.
Claim 4
Independent Claim
25 words
A method of secured communication as claimed in claims l or 2, wherein the random variable data words are generated in an external data base.
Claim 5
Independent Claim
45 words
A method of secured communication as claimed in claim l, wherein to provide network signalling, each exchange is given its own variable data word, and random variable data words are periodically issued to exchanges for use in encrypting and decrypting signalling messages across the network.
Claim 6
Dependent Claim
39 words
A method of secured communication as claimed in claim 4, wherein a bulk encryption data base is provided which sends updates of a message random variable data word and of a bulk random variable data word to the exchanges.
Claim 7
Dependent Claim
42 words
A method of secured communication as claimed in claim 5, wherein particular bits are used to transmit an n-bit number in each multiframe, the number being incremented every multiframe and being used to define where the following multiframe is in a sequence.
Claim 8
Dependent Claim
58 words
A method of secured communication as claimed in claim 6, wherein a change in a random variable data word is indicated by a further particular bit changing state, several multiframes in advance of the change, so that a new n-bit number can be generated to define the position in the sequence of the new random variable data word.