Systems and methods using cryptography to protect secure computing environments

• US 6,292,569 B1
• Filed: 10/04/2000
• Issued: 09/18/2001
• Est. Priority Date: 08/12/1996
• Status: Expired due to Term

• Current Assignee: Intertrust Technologies Corporation (Fidelio Acquisition Co LLC)
• Original Assignee: Intertrust Technologies Corporation (Fidelio Acquisition Co LLC)
• Inventors: Sibert, W. Olin, Shear, Victor H., Van Wie, David M.
• Primary Examiner(s): Buczinski, Stephen C.
• Application Number:
  US09/678,830
• Time in Patent Office: 349 Days
• Field of Search: 380/251, 380/255, 380/287, 713/155, 713/176, 713/180, 713/182, 713/194
• US Class Current: 380/255
• CPC Class Codes: G06F 12/1483 using an access-table, e.g. matrix or list
• CPC Class Codes: G06F 21/10 Protecting distributed programs or content, e.g. vending or licensing of copyrighted material protection in video systems or pay television H04N7/16 ; Digital rights management [DRM]
• CPC Class Codes: G06F 21/51 at application loading time, e.g. accepting, rejecting, starting or inhibiting executable software based on integrity or source reliability
• CPC Class Codes: G06F 2211/007 Encryption, En-/decode, En-/decipher, En-/decypher, Scramble, (De-)compress
• CPC Class Codes: G06Q 20/02 involving a neutral party, e.g. certification authority, notary or trusted third party [TTP]
• CPC Class Codes: G06Q 20/085 involving remote charge determination or related payment systems
• CPC Class Codes: G06Q 20/12 specially adapted for electronic shopping systems
• CPC Class Codes: G06Q 20/24 Credit schemes, i.e. "pay after"
• CPC Class Codes: G06Q 20/3674 involving authentication
• CPC Class Codes: G06Q 20/3823 combining multiple encryption tools for a transaction
• CPC Class Codes: G06Q 20/3825 Use of electronic signatures
• CPC Class Codes: G06Q 20/401 Transaction verification
• 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 20/00159 Parental control systems
• CPC Class Codes: G11B 20/00173 wherein the origin of the content is checked, e.g. determining whether the content has originally been retrieved from a legal disc copy or another trusted source
• CPC Class Codes: G11B 20/00188 involving measures which result in a restriction to authorised devices recording or reproducing contents to/from a record carrier
• CPC Class Codes: G11B 20/00195 using a device identifier associated with the player or recorder, e.g. serial numbers of playback apparatuses or MAC addresses
• CPC Class Codes: G11B 20/0021 involving encryption or decryption of contents recorded on or reproduced from a record carrier
• CPC Class Codes: G11B 20/00543 wherein external data is encrypted, e.g. for secure communication with an external device or for encrypting content on a separate record carrier
• CPC Class Codes: G11B 20/00557 wherein further management data is encrypted, e.g. sector headers, TOC or the lead-in or lead-out areas
• CPC Class Codes: G11B 20/00688 : said measures preventing that a usable copy of recorded data can be made on another medium
• CPC Class Codes: G11B 20/0071 : involving a purchase action
• CPC Class Codes: G11B 20/00768 : wherein copy control information is used, e.g. for indicating whether a content may be copied freely, no more, once, or never, by setting CGMS, SCMS, or CCI flags
• CPC Class Codes: G11B 2220/216 : Rewritable discs
• CPC Class Codes: G11B 2220/218 : Write-once discs
• CPC Class Codes: G11B 2220/2562 : DVDs [digital versatile discs]; Digital video discs; MMCDs; HDCDs
• CPC Class Codes: G11B 2220/2575 : DVD-RAMs
• CPC Class Codes: G11B 27/031 : Electronic editing of digitised analogue information signals, e.g. audio or video signals
• CPC Class Codes: G11B 27/329 : on a disc [VTOC]
• CPC Class Codes: H04L 12/40104 : Security; Encryption; Content protection cryptographic protocols H04L9/00; protocols for network security H04L63/00
• CPC Class Codes: H04L 12/40117 : Interconnection of audio or video/imaging devices home automation networks H04L12/2803; bitstream network arrangements specially adapted for distribution of digital video signals H04N7/24

Abstract

Secure computation environments are protected from bogus or rogue load modules, executables and other data elements through use of digital signatures, seals and certificates issued by a verifying authority. A verifying authority—which may be a trusted independent third party—tests the load modules or other executables to verify that their corresponding specifications are accurate and complete, and then digitally signs the load module or other executable based on tamper resistance work factor classification. Secure computation environments with different tamper resistance work factors use different verification digital signature authentication techniques (e.g., different signature algorithms and/or signature verification keys)—allowing one tamper resistance work factor environment to protect itself against load modules from another, different tamper resistance work factor environment. Several dissimilar digital signature algorithms may be used to reduce vulnerability from algorithm.

Claims

1. A security method comprising:

(a) digitally signing a first load module with a first digital signature designating the first load module for use by a first device class;

(b) digitally signing a second load module with a second digital signature different from the first digital signature, the second digital signature designating the second load module for use by a second device class having a tamper resistance and/or work factor substantially different from the tamper resistance and/or work factor of the first device class;

(c) distributing the first load module for use by at least one device in the first device class; and

(d) distributing the second load module for use by at least one device in the second device class.

2. A method including the following:

generating an executable program;

providing the program to a certification authority;

at the certification authority;

creating a first hash based on at least a portion of the program, the hash being based on a hashing algorithm;

selecting a security level, the security level being based on an attribute of the program or of the environment in which at least a portion of the program was modified or tested;

based at least in part on the selected security level, choosing a set of keys;

using a first key from the set of keys to digitally encrypt the hash so as to create a first digital signature;

using a second key from the set of keys to digitally encrypt the hash so as to create a second digital signature, the second key being different from the first key;

associating the first digital signature and the second digital signature with the program;

providing the program to a first electronic appliance, the first electronic appliance having a security level;

at the first electronic appliance;

determining whether the security level used by the certification authority for choosing the key set is compatible with the security level present at the first electronic appliance;

if the security level used by the certification authority is compatible with the first electronic appliance security level, using a third key stored at the first electronic appliance to decrypt the first digital signature, thereby retrieiving the first hash, the third key being a copy of or otherwise associated with the first key;

using the hashing algorithm to create a second hash of at least a portion of the program;

comparing the first hash to the second hash; and

if the first hash and the second hash are identical, then proceeding with a use of the program.

3. A method as in claim 2, further including:

generating a specification which at least in part describes the functioning of the program;

providing the specification to the certification authority;

at the certification authority, prior to the step of creating the first hash, comparing the program to the specification;

if the comparison fails, generating an indication that the program does not match the specification, and ending the process without creating the first hash or performing other steps; and

if the comparison succeeds, proceeding with the step of creating the first hash.

4. A method as in claim 3, further including:

at the certification authority;

using the hashing algorithm to create a third hash, the third hash being based on at least a portion of the specification,

prior to the use of the first key set to encrypt the first hash, combining the first hash and the third hash, so that the encryption steps apply to both the first hash and the third hash;

the step of providing the program to the first electronic appliance further includes providing the specification to the first electronic appliance; and

at the first electronic appliance;

the step of retrieving the first hash includes also retrieving the third hash;

using the hashing algorithm to create a fourth hash of at least a portion of the specification, and

comparing the third hash and the second hash.

5. A method as in claim 2, further including:

providing the program to a second electronic appliance, the second electronic appliance having a security level;

at the second electronic appliance;

determining whether the security level used by the certification authority for choosing the key set is compatible with the security level present at the second electronic appliance;

if the security level used by the certification authority is compatible with the second electronic appliance security level, using a fourth key stored at the first electronic appliance to decrypt the second digital signature, thereby retrieiving the first hash, the fourth key being a copy of or otherwise associated with the second key;

using the hashing algorithm to create a second hash of at least a portion of the program,

comparing the first hash to the second hash; and

if the first hash and the second hash are identical, then proceeding with a use of the program.

6. A method as in claim 2, further including:

providing the third key to the first electronic appliance, the third key being provided independently from the first digital signature.

7. A method as in claim 6, further including:

at the first electronic appliance, storing the third key in a tamper-proof manner such that the third key is at least somewhat protected from inspection by a user of the first electronic appliance.

8. A method as in claim 2, further including:

generating the third key at the first electronic appliance, the third key generation being based on a seed present at the first electronic appliance.

9. A method including the following:

generating a computer program;

providing the computer program to a first certification authority;

at the first certification authority;

generating a first digital certificate containing information relating to the computer program,

associating the first digital certificate with the computer program, and

providing the computer program to a second certification authority;

at the second certification authority;

generating a second digital certificate containing information relating to the computer program, and

associating the second digital certificate with the computer program;

providing the computer program to an electronic appliance; and

at the electronic appliance;

selecting whether to use the first digital certificate or the second digital certificate, the selection resulting in a decision to use the first digital certificate,

processing the first digital certificate to recover information relating to the computer program, and

using the first digital certificate information to determine whether to make a use of the computer program.

10. A method as in claim 9, in which:

generating the first digital certificate includes incorporating information relating to a security level associated with the computer program.

11. A method as in claim 10, in which:

the information recovered by the electronic appliance in the processing step includes the security level information, and

the use made of the recovered information by the electronic appliance includes determining whether the recovered security level information is consistent with a security level required by the electronic appliance or by a process running on the electronic appliance.

12. A method as in claim 9, in which:

generating the first digital certificate includes incorporating information about the first certification authority.

13. A method as in claim 12, in which:

the information recovered by the electronic appliance in the processing step includes the information about the first certification authority, and

the use made of the recovered information by the electronic appliance includes determining the extent to which the electronic appliance is authorized to accept digital certificates from the first certification authority.

14. A method as in claim 9, in which:

the step of determining whether to make a use of the computer program results in a negative determination, and

the electronic appliance then selects the second digital certificate and processes the second digital certificate to recover information relating to the computer program.