Method and apparatus for providing hierarchical key system in restricted-access television system

• US 6,069,957 A
• Filed: 03/07/1997
• Issued: 05/30/2000
• Est. Priority Date: 03/07/1997
• Status: Expired due to Term

• Current Assignee: Alcatel-Lucent USA, Inc. (Nokia Corporation)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Richards, William James
• Primary Examiner(s): Hayes, Gail O.
• Assistant Examiner(s): SAYADIAN, HRAYR
• Application Number:
  US08/810,441
• Time in Patent Office: 1,180 Days
• Field of Search: 380/10, 380/20, 380/210, 380/278, 380/281, 380/283, 380/284, 380/45
• US Class Current: 380/281
• CPC Class Codes: H04L 2209/601 Broadcast encryption
• CPC Class Codes: H04L 9/0836 using tree structure or hierarchical structure

Abstract

An encryption system for restricted-access television systems. Decryption keys, which are used to decrypt program material, are transmitted to customers in a restricted-access television system. The keys are transmitted as a hierarchy, wherein one key unlocks another key, and the last key unlocked is used to decrypt program material. Such a hierarchy is sometimes called "key-upon-key" encryption. The system transmits a second key that produces a first key from a cipher text (which first key decrypts a first program material) and wherein the second key also decrypts a second program material.

Claims

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

a) transmitting a first key which decrypts first program material; and

b) transmitting a second key which

i) produces the first key from cipher text; and

ii) decrypts second program material.

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

a) means for transmitting a first key which decrypts first program material; and

b) means for transmitting a second key which

i) produces the first key from cipher text; and

ii) decrypts second program material.