Secure transmission system for a digital trunked radio system
AssigneeM/A-COM Private Radio Systems, Inc.
InventorsJames F. Collum, William Oscar Janky, Eugene H. Peterson III
Life of this patent
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Abstract
A security system for a digital trunked radio system having a digital control channel and a plurality of working channels, wherein said working channels are assigned for temporary use of individual radio units by digital control signals transmitted over said control channel, said control channel carrying digital control signals between a base site and said radio units, comprising a digital key, said key used to limit access to the system equipment and system control channel transmissions.
Claims31
A method for secure communication within a digital trunked radio system having a digital control channel and a plurality of working channels, wherein said working channels are assigned for temporary use of individual radio units by digital control signals transmitted over said control channel, said control channel carrying digital control signals between a base site and said radio units, said method comprising the steps of:
- 1—selecting a digital key;
- 2—configuring both said base station and said radios with said key;
- 3—scrambling said digital control signals prior to transmission by performing an exclusive-or function between said digital control signals and said key
- 4—transmitting said scrambled signals over said control channel;
- and
- 5—unscrambling said scrambled signal upon receipt by performing a second exclusive—or function between said scrambled signal and said key.
An apparatus for secure transmission of radio communications over a digital trunked radio system comprising:
- at least one base site unit capable of transmitting and receiving radio communications, wherein said at least one base site unit is equipped with a digital security key for scrambling radio communications over said control channel;
- and
- a plurality of radio units capable of transmitting and receiving radio communications, wherein said radio units are equipped with a digital security key for unscrambling radio communications over said control channel;
- wherein said base site unit and said plurality of radio units communicate with each other using a digital control channel and a plurality of working channels, wherein said working channels are assigned for temporary use of said individual radio units by digital control signals transmitted over said control channel.
An apparatus as set forth in claim 19, wherein said 28 bits comprises 16 variable bits and 12 fixed bits.
An apparatus as set forth in claim 21, wherein said software changes said security key using said encryption algorithm at predetermined intervals.
A radio for use on a digital trunked radio system, wherein said system comprises a digital control channel and a plurality of working channels, wherein said working channels are assigned for temporary use of said radio by digital control signals transmitted over said control channel, said radio equipped with a digital security key for scrambling and unscrambling radio communications over said control channel.
A method for providing secure access of a user to system data stored on a terminal within a digital trunked radio system, said method comprising the steps of:
- 1—storing a first digital key on said terminal;
- 2—requiring a user to present a second digital key upon a request for access to said system data;
- and
- 3—comparing said first key and said second key, wherein access is permitted if said first key and said second key match.
An apparatus for limiting access of a user to system data stored on a terminal within a digital trunked radio system, said system comprising:
- a smart card, said smart card containing a first digital key;
- a terminal, said terminal containing:
- a second digital key,
- a circuit for reading said first digital key from said smart card,
- and a circuit for comparing said first digital key with said second digital key, wherein access to said system data stored on said terminal is allowed only if said first key and said second keys match.
Dependencies are inferred from the claim text.