Multiple keys for decrypting data in restricted-access television system

• US 6,690,795 B1
• Filed: 03/04/1997
• Issued: 02/10/2004
• Est. Priority Date: 03/04/1997
• Status: Expired due to Fees

• Current Assignee: Alcatel-Lucent USA, Inc. (Nokia Corporation)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Richards, William James
• Primary Examiner(s): SHEIKH, AYAZ R
• Assistant Examiner(s): SHEIKH, AYAZ R
• Application Number:
  US08/810,442
• Time in Patent Office: 2,534 Days
• Field of Search: 380/10, 380/20, 380/203, 380/210, 380/223, 380/226, 380/278, 380/284, 380/286
• US Class Current: 380/203
• CPC Class Codes: H04N 21/26606 for generating or managing entitlement messages, e.g. Entitlement Control Message [ECM] or Entitlement Management Message [EMM] arrangements for conditional access to broadcast information or to broadcast-related services H04H60/14
• CPC Class Codes: H04N 21/26613 for generating or managing keys in general key distribution for secret or secure communication involving central third party, e.g. key distribution center [KDC] or trusted third party [TTP] H04L9/083; network support of key management H04L63/06; key management for network security in communication control or processing H04W12/04
• CPC Class Codes: H04N 7/1675 Providing digital key or authorisation information for generation or regeneration of the scrambling sequence pseudo-random number generators in general G06F7/58

Abstract

An encryption system for restricted-access television systems. Multiple decryption keys are used to decrypt encrypted material which is transmitted to customers of a restricted-access television system.

Claims

1. In a restricted-access television system, the improvement comprising:

a) transmitting program material in digital packets which are encrypted by first keys which change at a first rate;

b) encrypting the first keys, by second keys which change at a second rate, less than the first;

c) transmitting information in digital packets which allow customers to recover said first keys, through said second keys; and

d) never exposing said keys to external view, outside an integrated circuit.