System and method for protecting data streams in hardware components

• US 7,069,590 B1
• Filed: 02/17/2000
• Issued: 06/27/2006
• Est. Priority Date: 02/17/2000
• Status: Expired due to Fees

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: England, Paul, Malvar, Henrique
• Primary Examiner(s): Moise, Emmanuel L.
• Assistant Examiner(s): CALLAHAN, PAUL E
• Application Number:
  US09/507,478
• Time in Patent Office: 2,322 Days
• Field of Search: 713/189, 713/193, 713/201, 380/283, 380/46, 380/201, 380/203, 380/217, 380/223, 380/287, 380/210, 705/57, 726/26, 726/28, 726/30, 726/29, 726/33
• US Class Current: 726/26
• CPC Class Codes: G11B 20/00086 Circuits for prevention of unauthorised reproduction or copying, e.g. piracy indicating unauthorised use of record carriers in general G11B23/28; scrambling for television signal recording H04N5/913; network architectures or network protocols for network security H04L63/00; cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00
• CPC Class Codes: G11B 20/0021 involving encryption or decryption of contents recorded on or reproduced from a record carrier
• CPC Class Codes: H04K 1/02 by adding a second signal to make the desired signal unintelligible
• CPC Class Codes: H04N 2005/91364 the video signal being scrambled
• CPC Class Codes: H04N 5/913 for scrambling ; for copy protection
• 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

A scrambling architecture protects data streams in the operating system and hardware components of a computer by scrambling the otherwise raw data prior to the data being handled by the operating system. The architecture has a scrambler implemented at either the client or the server that adds noise to the content. More specifically, the scrambler produces periodic sets of tone patterns having varying amplitudes based on a first key. The scrambler also generates a random signal based on the first key and a second key. The tone patterns and random signal are added to the content to scramble the content. The scrambled content is then passed to the filter graph (or other processing system) where the content is processed while scrambled. Any attacker attempting to siphon off the bits during processing will steal only noisy data, which is worthless for redistribution or copying purposes. After processing, the scrambled data is passed to a driver for output. The driver implements a descrambler to unscramble the content by subtracting out the random noise signal. The descrambler detects the tone patterns in the content and recovers the first key from the varying amplitudes of the tone patterns. The descrambler also receives the second key via a separate channel (e.g., a cryptographically secured path) and generates the same random signal using the recovered first key and the second key. The descrambler subtracts the tone patterns and the random signal from the scrambled content to restore the content.

Claims

1. A scrambling architecture for protecting content distributed by a content provider over a network to a client, comprising:

a content scrambler to scramble the content using first and second keys to produce scrambled content, the scrambler embedding the first key into the scrambled content and passing the second key on a separate channel from the scrambled content; and

a content descrambler to recover the first key from the scrambled content and to receive the second key, the descrambler unscrambling the scrambled content using the first and second keys to recover the content, and wherein the content scrambler is implemented at the client, so that the content is scrambled at the client after distribution over the network from the content provider.

2. A scrambling architecture as recited in claim 1, wherein the content scrambler and the content descrambler are implemented in software.

3. A scrambling architecture as recited in claim 1, wherein the content scrambler is implemented at the content provider, so that the content is scrambled prior to distribution over the network to the client.

4. A scrambling architecture as recited in claim 1, wherein the content descrambler is implemented within an operating system at the client.

5. A scrambling architecture as recited in claim 1, wherein the content descrambler is implemented within a driver at the client.

6. A scrambling architecture as recited in claim 1 wherein the content scrambler passes the second key to the content descrambler over a cryptographically secured path.

7. A scrambling architecture as recited in claim 1, wherein the content scrambler comprises:

a tone generator and modulator to create periodic sets of tone patterns and to modulate amplitudes of the sets based on the first key;

a random number generator to create a random signal based on the first and second keys; and

an adder to add the sets of tone patterns and the random signal to the content to produce the scrambled content.

8. A scrambling architecture as recited in claim 7, wherein the tone generator and modulator modulates the amplitudes in a way that embeds the first key into the sets of tone patterns.

9. A scrambling architecture as recited in claim 7, wherein the tone generator and modulator produces the tone patterns with one of two amplitudes, wherein tone patterns with a first amplitude represent a first binary value and tone patterns with a second amplitude represent a second binary value, the first key being encoded into the sets of tone patterns as an aggregate of the first and second binary values.

10. A scrambling architecture as recited in claim 7, wherein the content descrambler comprises:

a tone detector and demodulator to detect the periodic sets of tone patterns in the scrambled content and to demodulate the amplitudes of the sets to recover the first key;

a random number generator to create a random signal based on the recovered first key and the second key; and

a subtractor to subtract the tone patterns and the random signal from the scrambled content to recover the content.