Method and apparatus for controlling access to a communication system

• US 4,992,783 A
• Filed: 04/04/1988
• Issued: 02/12/1991
• Est. Priority Date: 04/04/1988
• Status: Expired due to Term

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Zdunek, Kenneth J., Schorman, Eric R., Bieri, Philip A.
• Primary Examiner(s): Yusko, Donald J.
• Assistant Examiner(s): Holloway, III, Edward C.
• Application Number:
  US07/176,951
• Time in Patent Office: 1,044 Days
• Field of Search: 340/825.34, 340/825.31, 340/825.5, 340/825.3, 235/380, 235/382, 235/382.5, 380/3, 380/21, 380/23, 380/25, 380/46, 379/85
• US Class Current: 340/5.74
• CPC Class Codes: H04L 63/083 using passwords cryptographic mechanisms or cryptographic arrangements for entity authentication using a predetermined code H04L9/3226
• CPC Class Codes: H04L 63/108 when the policy decisions are valid for a limited amount of time
• CPC Class Codes: H04W 12/06 Authentication
• CPC Class Codes: H04W 12/08 Access security

Abstract

All subscribers operating within a communication system initially generate and transmit a random password and their ID code to the operation (control) center of a communication system. Thereafter, in a first embodiment, subscribers are commanded to modify (in a predetermined manner) and re-transmit their password and ID code either periodically or upon requesting access to the communication system. The modified password is retained as the current (authorized) password by both the subscriber and the system. In a second embodiment, subscribers are commanded to generate and transmit a new random password and their ID code to the system, which maintains a history of each subscriber'"'"'s current and previous passwords. According to the invention, some of the subscribers having an unauthorized (duplicated) ID code may be inactive (off) when the subscriber is commanded to modify or generate a password. In this way, one of the subscribers having an unauthorized (duplicated) ID code will become out-of-sync with the system, and eventually transmit an unauthorized password. When the system receives an incorrect password for an out-of-sync subscriber, access to the communication system may be denied, and the subscribers that duplicate (or permit others to duplicate) ID codes may be identified.

Claims

1. In a two-way communication system having a central unit and a plurality of subscriber units each having at least an identification code stored therein, a method of controlling access to the two-way communication system comprising the steps of:

in at least one of said plurality of subscriber units;

(a) generating a first random number as a first password code;

(b) transmitting at least said first password code and said identification code;

(c) receiving a command code and generating a second random number as a second password code in response thereto;

(d) transmitting at least said second password code and said identification code.

2. In a two-way communication system having a central unit and a plurality of subscriber units each having at least an identification code and a first password code stored therein, a method of controlling access to the two-way communication system comprising the steps of:

(a) transmitting at least a call request code;

(b) receiving a command code and generating a random number as a second password code in response thereto;

(c) transmitting at least said second password code and said identification code; and

(d) receiving a channel grant code.

3. In a two-way communication system having a central unit and a plurality of subscriber units each having at least an identification code and a first password code stored therein, a method of controlling access to the two-way communication system comprising the steps of:

in at least one of said plurality of subscriber units;

(a) receiving a command code and generating a random number as a second password code in response thereto;

(b) transmitting at least said second password code and said identification code.

4. In a two-way communication system having a central unit and a plurality of subscriber units each having at least an identification code stored therein, a method of controlling access to the two-way communication system comprising the steps of:

in at least one of said plurality of subscriber units;

(a) generating a first random number as a first password code;

(b) transmitting at least said first password code and said identification code;

(c) receiving a command code and generating a second random number as a second password code in response thereto;

(d) transmitting at least said second password code and said identification code;

at said central unit;

(a) receiving said first password code;

(b) transmitting said command code;

(c) receiving said second password code.

9. The method of claim 4 or 8, which includes the central unit steps of:

(a1) storing said first received password code, and operating thereafter using said first received password code as a current password code;

(c) storing said second received password code, and operating thereafter using said first received password code as a previous password code, and using said second received password code as said current password code.

12. The method of claim 4 or 8, which includes the central unit steps of:

(a1) storing said first password code as a current password;

(c) storing said first password code as a prior password; and

,

storing said second password code as said current password.

5. In a two-way communication system having a plurality of subscriber units each having at least an identification code and a first password code stored therein and at least one central unit designating said first password code as a current password code, a method of controlling access to the two-way communication system comprising the steps of:

in at least one of said plurality of subscriber units;

(a) transmitting at least a call request code;

(b) receiving a command code and generating a random number as a second password code in response thereto;

(c) transmitting at least said second password code and said identification code; and

(d) receiving a channel grant code,

at said at least one central unit;

(a) receiving at least said call request code;

(b) transmitting said command code;

(c) receiving at least said second password code;

(d) determining whether said second password correlates to a current password;

(e) granting access to said two-way communication system if said second password correlates to said current password.

10. The method of claims 5 or 6, which includes the central unit step of:

(c1) storing said second received password code, and operating thereafter using said first received password code as a previous password code, and using said second received password code as a current password code.

11. The method of claim 5 or 8, which includes the central unit step of:

(c) transmitting a channel grant code.

6. In a two-way communication system having a central unit and a plurality of subscriber units each having at least an identification code and a first password code stored therein, a method of controlling access to the two-way communication system comprising the steps of:

in at least one of said plurality of subscriber units;

(a) receiving a command code and generating a random number and a second password code in response thereto;

(b) transmitting at least said second password code and said identification code;

at said central unit;

(a) transmitting said command code;

(b) receiving at least said second password code.

7. In a two-way communication system having a central unit and a plurality of subscriber units each having at least an identification code stored therein, a method of controlling access to the two-way communication system comprising the steps of:

in at least one of said plurality of subscriber units;

(a) generating a first random number as a first password code;

(b) transmitting at least said first password code and said identification code;

(c) generating a second random number as a second password code in response to a control signal;

(d) transmitting at least said second password code and said identification code; and

,

(e) receiving a channel grant code.

8. In a two-way communication system having a central unit and a plurality of subscriber units each having at least an identification code stored therein, a method of controlling access to the two-way communication system comprising the steps of:

in at least one of said plurality of subscriber units;

(a) generating a first random number as a first password code;

(b) transmitting at least said first password code and said identification code;

(c) generating a second random number as a second password code in response to a control signal;

(d) transmitting at lest said second password code and said identification code; and

(e) receiving a channel grant code;

at said central unit;

(a) receiving said first password code;

(b) receiving said second password code.

13. In a two-way communication system having a plurality of subscriber units each having at least an identification code and a first password code stored therein and at least one central unit designating said first password code as a current password code, a method of controlling access to the two-way communication system comprising the steps of:

in at least one of said plurality of subscriber units;

(a) transmitting at least said call request code;

(b) receiving a command code and generating a second password code in response thereto;

(c) transmitting at least said second password code and said identification code;

at said at least one central unit;

(a) receiving at least said call request code;

(b) transmitting said command code;

(c) receiving at least said second password code;

(d) determining whether said second password correlates to a current password;

(e) determining whether said second password correlates to a prior password;

(f) granting access to said two-way communication system when said second password correlates with said current password or does not correlate to said prior password and does not correlate to said current password, else denying access to said two-way communication system.

14. In a two-way communication system having a plurality of subscriber units each having at least an identification code and a first password code stored therein and at least one central unit having stored therein at least one current password and at least one prior cross-referenced to said identification codes of said plurality of subscriber units, a method of controlling access to the two-way communication system comprising the steps of:

at said at least one central unit;

(a) receiving at least a password code and an identification code to provide a received password;

(b) determining whether said received password correlates to a current password;

(c) determining whether said received password correlates to a prior password;

(d) granting access to said two-way communication system if said received password correlates to said current password or does not correlate to said prior password and does not correlate to said current password, else denying access to said two-way communication system.